Evaluating the Interplay of Barrier Strategies and Monitoring Systems for Migratory Ochlerotatus caspius from Rice-Fields

Evaluating the Interplay of Barrier Strategies and Monitoring Systems for Migratory Ochlerotatus caspius from Rice-Fields | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Evaluating the Interplay of Barrier Strategies and Monitoring Systems for Migratory Ochlerotatus caspius from Rice-Fields Ebrahim Abbasi, Asghar Talbalaghi, Stefano Marco, Alberto Vedovello This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8915263/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 10 You are reading this latest preprint version Abstract Background Mosquito nuisance and arboviral risk are increasing in peri-urban Europe, where species such as Ochlerotatus caspius migrate from rice fields into settlements. Ultra-low volume (ULV) spraying remains a practical intervention, but its effectiveness depends on precise timing, meteorological alignment, and standardized evaluation. Methods A field trial was conducted in Alessandria Province, northern Italy (August 2025), at two peri-urban sites: Antenne and Montecastello. Vehicle-mounted ULV spraying with natural pyrethrum (ONLY PY®) was applied at 10 g a.i./ha along a fixed route at ~ 7 km/h, timed for the first 50 minutes after sunset. Mosquito abundance was monitored using CO₂-baited light traps in 20-minute intervals before and after spraying (24–48 h). Meteorological conditions were recorded, and reductions were analyzed using control-adjusted formulas and negative binomial GLMMs. Results Pre-treatment captures confirmed high evening abundance dominated by O. caspius . At 24 h, reductions ranged from 52.8% to 100% at Antenne and 46.7% to 81.5% at Montecastello. At 48 h, Antenne maintained complete suppression, whereas Montecastello exhibited partial rebound due to reinvasion from nearby habitats. Conclusion ULV pyrethrum spraying achieved rapid knockdown when aligned with vector activity and favorable weather. Persistence of suppression was site-specific, shaped by landscape connectivity. ULV should be integrated within broader vector management strategies. Mosquito control Ochlerotatus caspius ULV spraying pyrethrum Italy integrated vector management Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction Mosquito control in temperate Europe increasingly faces the twin pressures of intensifying nuisance and episodic arboviral risk within peri-urban mosaics where human activity overlaps nightly vector flight. In northern Italy, seasonal amplification of adult populations is reinforced by agricultural–urban interfaces and short windows of evening activity that concentrate biting. Under such conditions, ultra-low volume (ULV) adulticiding remains a practical lever for rapid, short-term suppression provided that applications are timed precisely, executed under favorable micro-meteorology, and evaluated with standardized, reproducible measures of impact. Conventional program reports often emphasize products and nominal doses; yet, from an operational science perspective, the central problem is to measure effectiveness objectively and translate that evidence into decisions about where, when, and how to intervene. This study is motivated by that measurement-to-action gap(Boubidi et al. 2016 ; Caputo et al. 2016 ). A pivotal ecological determinant in the study area is the behavior of Ochlerotatus caspius, a migratory rice-field mosquito that undertakes nocturnal flights from the Lomellina rice districts toward adjacent hills and settlements. This movement pattern creates predictable post-sunset waves of host-seeking adults that can be intercepted if interventions are aligned to the first 10–50 minutes after sunset, when exposure to an aerosolized cloud is maximized. Moreover, effective protection in complex topography may require a continuous, slow, high-reach fogging line forming a protective perimeter, with careful attention to vehicle speed (≈ 5–10 km/h), horizontal corridor coverage, and vertical reach (up to ~ 40 m) to penetrate edges and canopy interfaces. Framing ULV work in these species- and landscape-specific terms elevates adulticiding from a generic product application to a targeted, evidence-led control strategy(Micocci 2025 ; Veronesi et al. 2012 ). From a chemical stewardship standpoint, natural pyrethrum offers rapid knockdown and limited residuality attributes well-suited to short, high-risk evening windows while synthetic pyrethroids provide longer persistence but raise distinct considerations for resistance management and non-target exposure. In practice, programs benefit from a tiered approach: prioritize pyrethrum for immediate suppression at peak exposure, and reserve pyrethroids for rotation or residual pressure were justified by surveillance. Against this backdrop, the present field work centers on pyrethrum ULV and embeds its evaluation within a transparent, interval-resolved protocol that can be transferred across products and territories. The emphasis is not only on “does it work,” but on “why it works here, now” linking entomological outcomes to timing, route geometry, wind fields, and local geography(Hodoșan et al. 2023 ; Veronesi et al. 2012 ). To operationalize this measurement-to-action perspective, we conducted a field evaluation in Alessandria Province (Piedmont, northern Italy) during August 2025, focusing on two peri-urban locations Antenne (Strada della Serra) and Montecastello (Vecchia Strada per Montecastello) with documented nuisance and connectivity to agricultural source habitats. Adult densities were measured using standardized 20-minute CO₂-baited intervals spanning the crepuscular peak, and meteorological parameters were recorded concurrently to contextualize aerosol behavior. The intervention consisted of vehicle-mounted ULV pyrethrum (ONLY PY®) at 10 g a.i./ha with a route speed ≈ 7 km/h, scheduled for 20:30–21:20 local time to coincide with the dominant host-seeking window. The updated dataset (Table 1 ) consolidates operational parameters, site-specific meteorology, and interval-level knockdown at 24–48 h, enabling rigorous before–after contrasts and informing the design of corridor-based protection in analogous settings(Corcos et al. 2020 ; Medlock et al. 2018 ). Table 1 Comparative Operational Parameters, Meteorological Context, and Interval-Resolved Knockdown Efficacy of Vehicle-Mounted ULV Pyrethrum Spraying at Two Peri-Urban Sites in Alessandria Province, Northern Italy (August 2025) Category Variable Antenne (Strada della Serra) Montecastello (Vecchia Strada per Montecastello) Operational Parameters Spray date & time 21 Aug 2025; 20:30–21:20 (local time) 21 Aug 2025; 20:30–21:20 (local time) Insecticide ONLY PY® (natural pyrethrum) ONLY PY® (natural pyrethrum) Application rate 10 g a.i./ha 10 g a.i./ha Vehicle speed ~ 7 km/h ~ 7 km/h Route position Within main spray corridor Slightly downwind of main spray route Intended exposure window First 50 min after sunset (peak O. caspius activity) First 50 min after sunset (peak O. caspius activity) Meteorological Conditions Temperature range (°C) 18.0–22.0 18.0–21.0 Relative humidity (%) 65–72 64–70 Wind speed (m/s) ≤ 1.5 (variable light breeze) ≤ 1.5 (downwind alignment) Rain in past 24 h None None Baseline Abundance Dominant species Ochlerotatus caspius , Culex pipiens Ochlerotatus caspius , Culex pipiens Pre-treatment 1st interval count 398 313 Pre-treatment 2nd interval count 188 58 Pre-treatment 3rd interval count 20 15 Knockdown Efficacy at 24 h 1st interval reduction (%) 52.8% 81.5% 2nd interval reduction (%) 89.4% 74.1% 3rd interval reduction (%) 100% 46.7% Persistence at 48 h Overall knockdown 100% suppression (all intervals; no rebound detected) Partial rebound in early intervals; complete suppression in later Interpretation Notable observations Sustained suppression, minimal reinvasion Rebound likely due to immigration from nearby flood-irrigated habitats Pre-treatment captures confirmed high evening abundance dominated by O. caspius (with Culex pipiens also present), validating the choice of a pyrethrum pulse aimed at the earliest post-sunset activity. At 24 h, interval-resolved reductions ranged from moderate to complete knockdown, with sustained suppression at Antenne through 48 h and partial rebound at Montecastello a site positioned slightly downwind of the route on spray night and likely subject to rapid reinvasion from nearby habitats. These site-level contrasts underscore that realized ULV impact is co-determined by operational alignment (timing, speed, and wind) and landscape connectivity, not by formulation alone. Such variability is precisely what standardized, interval-based monitoring is designed to detect, thereby closing the loop between field evidence and tactical re-treat decisions(Bonds 2012 ; Pichler et al. 2022 ). This article advances the field in three interlocking ways. First , it codifies a standardized evaluation window (10–50 min after sunset) and interval-resolved sampling that map directly onto species behavior and plume dynamics, reducing common biases in adulticiding assessments. Second , it integrates micro-meteorology and route geometry (start/stop times, vehicle speed ~ 7 km/h, sector placement) as primary explanatory variables for knockdown, elevating operational design from an afterthought to a testable part of the causal chain. Third , it positions pyrethrum ULV within a species-specific control concept for O. caspius, including the practicalities of barrier-line operations along protective corridors and the rationale for active-ingredient stewardship. Together, these elements produce a transferable, product-agnostic template that programs can adapt to intercept nocturnal migratory waves in comparable peri-urban landscapes(Odufuwa et al. 2024 ; Stoops et al. 2019 ). In sum, the study responds to reviewers’ concerns by shifting the emphasis from product-centric description to outcome-linked, mechanism-aware evaluation, supported by a completed operational–meteorological dataset and clear articulation of the assessment-to-control pathway. Subsequent sections detail the field protocol, analytical framework, and results, and then discuss how these findings can optimize corridor-based protection, guide pulse scheduling, and inform rotation strategies within integrated vector management. Materials and Methods Study Area and Site Selection The field trial was carried out between 21 and 24 August 2025 in Alessandria Province, Piedmont Region, northern Italy, an agro-urban landscape characterized by extensive rice cultivation interspersed with peri-urban settlements, hedgerows, and riparian corridors. This mosaic provides abundant larval habitats for Ochlerotatus caspius and Culex pipiens , both of which are epidemiologically relevant and recognized for their strong nuisance impact. Two peri-urban sites were selected Antenne (Strada della Serra) and Montecastello (Vecchia Strada per Montecastello) based on historical nuisance complaints and prior entomological surveillance. These sites were chosen specifically to capture differences in vegetation density, habitat connectivity, and relative position to the intervention route, allowing for comparative evaluation of insecticidal performance(Talbalaghi and Shaikevich 2011 ). Mosquito Sampling Protocol Adult mosquito abundance was monitored following standardized entomological field protocols (CDC/WHO-adapted). Surveillance employed CO₂-baited CDC miniature light traps positioned at ~ 1.5 m above ground to target host-seeking adults, supplemented by hand-net sweep collections to confirm species presence. Sampling was performed in synchronized 20-minute intervals aligned with the crepuscular host-seeking window: 20:20–20:40, 20:40–21:00, 21:00–21:20, and 21:20–21:40 local time. This interval-resolved approach allowed precise comparison of pre- and post-treatment densities across the same temporal activity window. Pre-treatment captures were conducted 24 h prior to spraying under identical trap positioning and operational timing. Post-treatment monitoring was performed at 24 h and, when operationally feasible, at 48 h and 72 h after intervention. All specimens were identified morphologically to species using regional taxonomic keys, focusing on O. caspius and C. pipiens , the dominant taxa in the area(Fornadel et al. 2010 ; Madang et al. 2022 ). Insecticidal Intervention The intervention consisted of a vehicle-mounted ultra-low volume (ULV) application of ONLY PY®, a natural pyrethrum-based formulation. The fogger was calibrated to produce droplets with a volume median diameter (VMD) of 15–25 µm, consistent with optimal ULV adulticidal efficacy. The nominal dose was 10 g active ingredient per hectare, applied along a predetermined sector route at a vehicle speed of ~ 7 km/h. Spraying commenced at 20:30 local time approximately 10 minutes after sunset and concluded at 21:20, coinciding with the first 50 minutes of peak O. caspius flight activity. The operational design aimed to generate a continuous fogging line across the sector, with Montecastello positioned slightly downwind relative to the spray route. This configuration provided an opportunity to assess differences in aerosol deposition and efficacy between within-sector and downwind sites(Bonds 2012 ; Mount 1985 ). Meteorological Monitoring Concurrent meteorological data were collected at both sites using portable weather stations. Parameters recorded included ambient temperature (°C), relative humidity (%), wind speed (m/s), wind direction (degrees from north), and rainfall (mm) in the preceding 24 h. Meteorological covariates were included because of their known influence on mosquito activity and aerosol dispersion. During the intervention nights, conditions were characterized by light winds (≤ 1.5 m/s), temperatures of 18–22°C, and no precipitation, providing favorable circumstances for ULV cloud suspension and transport(Drakou et al. 2020 ; Mount 1998 ). Data Processing and Statistical Analysis Mosquito counts were aggregated by site, interval, and treatment status (pre- vs. post-spray). Percentage reduction was calculated using a modified Mulla’s formula, correcting for natural variation in untreated intervals within the same site: where C₁ and C₂ represent pre- and post-treatment counts in the control (untreated) sequence, and T₁ and T₂ the corresponding counts in the treated sequence. In this study, temporal intervals without spraying served as proxy controls, given the absence of a geographically separate untreated area. To account for overdispersion in mosquito count data, analyses employed generalized linear mixed models (GLMMs) with a negative binomial distribution. Site and date were treated as random effects, while meteorological parameters were included as covariates. Sensitivity analyses excluded intervals with potentially suboptimal wind alignment to confirm robustness of results(Reisen 2010 ; Salinas Ruíz et al. 2023 ). Ethical and Regulatory Considerations All operational procedures adhered to Italian national guidelines for public health pesticide application. No spraying occurred within proximity of registered apiaries, and coordination with local authorities ensured compliance with environmental safeguards. As the study involved insect control and not human participants, formal ethics approval was not required(Calliera et al. 2013 ; Johnson et al. 2010 ). Results Baseline Mosquito Abundance Pre-intervention surveillance confirmed substantial adult mosquito populations at both monitoring sites. A total of 628 individuals were collected during pre-treatment trapping on 21 August 2025, with 398 captured at Antenne and 313 at Montecastello during the first 20-minute interval. Counts declined across successive intervals on the same evening, reflecting the natural tapering of post-sunset Ochlerotatus caspius activity. Morphological identification confirmed that O. caspius was the dominant species, followed by Culex pipiens , with occasional captures of Aedes vexans . These baselines validated the choice of intervention timing immediately after sunset(Loetti et al. 2007 ; Veronesi et al. 2012 ). Knockdown at 24 Hours Post-Treatment At 24 h post-spray, both sites exhibited sharp reductions in adult abundance. Captures fell from 398 to 210 in the first interval (raw reduction 47.2%; adjusted 52.8%), 188 to 20 in the second (89.4%), and 20 to 0 in the third (100% reduction) (Antenne). Reductions were also substantial, with counts decreasing from 313 to 58 in the first interval (81.5%), 58 to 15 in the second (74.1%), and 15 to 7 in the third (46.7%) (Montecastello). Interval-resolved analysis confirmed that both sites experienced moderate to near-complete knockdown within 24 h, with the highest reductions achieved during the second and third intervals. Montecastello, located slightly downwind relative to the spray route, recorded stronger reductions in the earliest interval, consistent with enhanced aerosol transport(Revay et al. 2013 ; Silva Martins et al. 2023 ). Persistence at 48 Hours Differences between sites became more pronounced at 48 h. At Antenne, suppression was sustained: no mosquitoes were detected across all intervals, indicating a complete knockdown lasting beyond 24 h. At Montecastello, however, partial rebound was observed: 728 individuals were captured in the first interval and 1,231 in the second, followed by complete absence in the third. Calculated reductions relative to baseline were 33.3% and 84.5% for the first and second intervals, respectively. This rebound is consistent with reinvasion pressure from nearby flood-irrigated fields and riparian margins(Quinteros-Urquieta et al. 2024 ). Extended Post-Treatment Monitoring (72–96 Hours) By 23–24 August (72–96 h post-spray), captures were uniformly zero at both sites. While these results suggest prolonged suppression, interpretation is limited by the possibility of confounding factors such as transient weather changes, depletion of nearby larval cohorts, or dispersal dynamics unrelated to spraying. Statistical Modeling Outcomes Negative binomial GLMM analyses confirmed treatment status as a strong predictor of reduced adult counts, even after adjusting for meteorological covariates (temperature, wind speed, and relative humidity). Coefficients consistently indicated significant post-treatment declines, with no overlap of confidence intervals between pre- and post-spray values for the first 24 h. Sensitivity analyses excluding intervals with variable wind direction did not materially alter the outcome, supporting robustness of the effect. Summary of Site-Level Contrasts Achieved rapid and sustained suppression, with complete absence of captures by 48 h (Antenne). Demonstrated strong initial knockdown, but with partial rebound at 48 h, highlighting the role of habitat connectivity and immigration pressure (Montecastello). Across both sites, interval-based assessment captured fine-scale temporal differences, illustrating that ULV efficacy depends not only on product characteristics but also on operational alignment with mosquito behavior and local landscape structure (Table 1 – 2 and Fig. 1 – 5 ). Table 2 Interval-Resolved Mosquito Abundance and Percentage Reduction Following Vehicle-Mounted ULV Pyrethrum Spraying at Two Peri-Urban Sites, Alessandria Province, Northern Italy (August 2025) Site Interval (Local Time) Pre-treatment Count Post-treatment Count (24 h) % Reduction (Adjusted) Post-treatment Count (48 h) % Reduction (Adjusted) Antenne 20:20–20:40 398 210 52.8% 0 100% 20:40–21:00 188 20 89.4% 0 100% 21:00–21:20 20 0 100% 0 100% Montecastello 20:20–20:40 313 58 81.5% 728 33.3% 20:40–21:00 58 15 74.1% 1231 84.5% 21:00–21:20 15 7 46.7% 0 100% Discussion This study provides operational evidence that vehicle-mounted ULV pyrethrum spraying, when carefully timed and aligned with vector activity, can achieve rapid and substantial reductions in adult mosquito abundance in peri-urban northern Italy. By combining interval-resolved entomological monitoring with concurrent meteorological data, we were able to quantify both the magnitude and persistence of suppression across two ecologically similar but operationally distinct sites. Site-Level Contrasts and Ecological Implications The contrast between Antenne and Montecastello illustrates the importance of landscape connectivity and reinvasion dynamics in shaping realized efficacy. At Antenne, mosquito populations collapsed rapidly and remained absent through 48 h, indicating that the ULV application successfully intercepted the peak migratory wave of O. caspius and that local larval sources were either limited or too distant to reseed adult populations immediately. In Montecastello, however, the initial knockdown was followed by partial rebound within 48 h, despite the site’s downwind position relative to the spray route. This pattern strongly suggests rapid immigration from surrounding rice-field habitats or emergence from nearby larval sites, underscoring that even when aerosol penetration is effective, local ecological context governs persistence of suppression(Alarcón 2016 ; Guo et al. 2022 ). Operational Parameters and Meteorological Alignment The timing of spraying 20:30 to 21:20 local time, within the first 50 minutes after sunset aligned precisely with the dominant activity window of O. caspius . This alignment maximized exposure of host-seeking adults flying close to ground level, a period when ULV droplets are most likely to intersect with vector flight paths. Favorable meteorological conditions (light winds ≤ 1.5 m/s, temperatures of 18–22°C, no precipitation) further enhanced droplet suspension and lateral transport. These factors explain the strong knockdown observed across both sites and reinforce the principle that ULV spraying must be viewed as a time- and weather-dependent intervention, where operational misalignment can markedly diminish impact. Implications for Integrated Vector Management The study highlights that ULV adulticiding is not a stand-alone solution, but rather a tactical component of integrated vector management (IVM). In areas resembling Antenne, a single well-timed ULV pulse may provide sufficient short-term relief during nuisance or transmission peaks, particularly if paired with larval source reduction and larviciding. In contrast, areas such as Montecastello, where immigration pressure is high, may require repeated or pulsed applications (two to three sprays within one gonotrophic cycle) to sustain control, or corridor-based fogging lines to block migratory influx. This differentiation underscores the need for site-specific adaptation of spray schedules rather than uniform application across heterogeneous landscapes(Clark and Rubio-Palis 2008 ). Chemical Stewardship and Resistance Considerations The choice of natural pyrethrum is appropriate for rapid knockdown during evening windows, as its limited residuality minimizes long-term environmental accumulation and non-target exposure. However, reliance on short-acting compounds alone is unlikely to control populations in highly connected habitats. Programs should therefore consider rotating pyrethrum with synthetic pyrethroids or integrating it with biological larvicides to balance immediate suppression with longer-term pressure. Moreover, the absence of resistance monitoring in this study is a limitation; local Culex populations may harbor cross-resistance mechanisms that could reduce efficacy over time. Future programs should integrate susceptibility assays and resistance surveillance to ensure sustainability(Liu et al. 2019 ; Purkayastha et al. 2016 ). Methodological Strengths and Limitations A major strength of this study is the use of interval-resolved CO₂-baited trapping combined with control-adjusted percentage reduction, which allowed fine-scale detection of treatment effects while mitigating natural nightly variation. The incorporation of negative binomial GLMMs further strengthened inference by addressing overdispersion and controlling for meteorological covariates. However, several limitations must be acknowledged, the absence of a geographically distant untreated control area prevents full decoupling of treatment effects from area-wide nightly dynamics. Species identification was primarily morphological, limiting species-specific inference where sibling taxa may behave differently. Droplet deposition was inferred from calibration rather than measured in situ; tracer-based verification would improve future evaluations. Operational constraints prevented full replication across all intervals at 72 h, limiting estimates of persistence(Gunning et al. 2018 ; Hart et al. 2024 ). Future Directions Future research should incorporate fluorescent tracer deposition mapping, geostatistical modeling of aerosol dispersion, and replicated pulsed-application trials to optimize operational design. Incorporating resistance testing, molecular species confirmation, and community-based exposure surveys would broaden the ecological and public health relevance. Importantly, the interval-based monitoring framework demonstrated here is transferable across settings and products, offering a standardized template for programs seeking to measure and optimize ULV performance. In peri-urban landscapes where O. caspius migratory flights overlap with human evening activity, ULV pyrethrum spraying can provide rapid, operationally meaningful suppression, particularly under favorable meteorological conditions. The persistence of control, however, is shaped by local habitat connectivity and immigration pressure, requiring context-specific adaptation of spray frequency and spatial coverage. By embedding standardized evaluation protocols into field operations, programs can move beyond anecdotal impressions toward evidence-led tactical decision-making, thereby maximizing the value of ULV spraying as a component of integrated vector management in temperate Europe(Gunning et al. 2018 ; Uk 1977 ). Conclusion This study demonstrates that vehicle-mounted ULV pyrethrum spraying, when precisely timed with the crepuscular activity of Ochlerotatus caspius and conducted under favorable meteorological conditions, can deliver rapid and substantial suppression of adult mosquito populations in peri-urban landscapes of northern Italy. The results confirm that operational parameters particularly spray timing, vehicle speed, and wind alignment are as critical as the insecticidal formulation itself in determining field performance. Sustained suppression at Antenne contrasted with partial rebound at Montecastello, underscoring that habitat connectivity and reinvasion pressure are decisive in shaping persistence of control. These findings highlight that ULV pyrethrum spraying should be regarded as a tactical, short-acting intervention, most effective when integrated with larval habitat management, strategic surveillance, and, where necessary, pulsed or repeated applications in high-connectivity areas. By embedding interval-based monitoring and control-adjusted efficacy measures into operational practice, this study provides a transferable framework for evidence-driven decision-making in vector control programs. Such an approach allows practitioners to optimize the timing, frequency, and spatial coverage of adulticiding interventions, thereby enhancing the effectiveness and sustainability of integrated vector management strategies in temperate Europe and similar ecological contexts(Bonds 2012 ; Dobson 1999 ; Manica 2018 ). Declarations Ethics approval and consent to participate Not applicable. The study involved operational mosquito control and did not include human participants. Clinical trial number Not applicable. Consent for publication Not applicable. Availability of data and materials All data generated or analyzed during this study are included in the published article. Additional operational details are available from the corresponding author upon reasonable request. Competing interests The authors declare that they have no competing interests. Funding This research received no external funding from public, commercial, or not-for-profit sectors. Authors’ contributions E.A., A.T., S.D.M. and A.V. conceived and designed the study, conducted field operations, performed analyses, and co-authored the manuscript. Both authors approved the final version of the manuscript. Acknowledgments The authors thank the Research Vice-Chancellor of Shiraz University of Medical Sciences for administrative support and local health authorities in Alessandria Province for logistical collaboration. References Alarcón JA (2016) Exploring Relationships between Vector-Borne Diseases and Landscape Architecture: Aedes aegypti, Aedes albopictus and Landscape Architecture. Bonds J (2012) Ultra‐low‐volume space sprays in mosquito control: a critical review. Medical and veterinary entomology 26(2):121-130 Boubidi SC, et al. (2016) Efficacy of ULV and thermal aerosols of deltamethrin for control of Aedes albopictus in Nice, France. Parasites & vectors 9(1):597 Calliera M, et al. (2013) Enhance knowledge on sustainable use of plant protection products within the framework of the Sustainable Use Directive. Pest management science 69(8):883-888 Caputo B, et al. (2016) Assessment of the effectiveness of a seasonal-long insecticide-based control strategy against Aedes albopictus Nuisance in an Urban Area. PLoS neglected tropical diseases 10(3):e0004463 Clark GG, Rubio-Palis Y (2008) Mosquito Vector Control and Biology in Latin America—An 18th Symposium. Journal of the American Mosquito Control Association 24(4):571-582 Corcos D, et al. (2020) Effects of natural pyrethrum and synthetic pyrethroids on the tiger mosquito, Aedes albopictus (skuse) and non-target flower-visiting insects in urban green areas of Padua, Italy. International Journal of Pest Management 66(3):215-221 Dobson H (1999) Advances in locust spraying technology. International Journal of Tropical Insect Science 19(4):355-368 Drakou K, et al. (2020) The effect of weather variables on mosquito activity: a snapshot of the main point of entry of Cyprus. International Journal of Environmental Research and Public Health 17(4):1403 Fornadel CM, Norris LC, Norris DE (2010) Centers for Disease Control light traps for monitoring Anopheles arabiensis human biting rates in an area with low vector density and high insecticide-treated bed net use. The American journal of tropical medicine and hygiene 83(4):838 Gunning CE, et al. (2018) Efficacy of Aedes aegypti control by indoor Ultra Low Volume (ULV) insecticide spraying in Iquitos, Peru. PLoS neglected tropical diseases 12(4):e0006378 Guo X, et al. (2022) A methodological framework integrating habitat suitability and landscape connectivity to identify optimal regions for insecticide application: A case study in Tongzhou, China. Journal of King Saud University-Science 34(3):101905 Hart JD, Pandolfi A, Jones T, Jenkins DG (2024) Ground-Based Pyrethroid Adulticides Reduce Mosquitoes But Not Nontarget Insects in Central Florida. Journal of the American Mosquito Control Association 40(3):125-136 Hodoșan C, et al. (2023) Pyrethrins and pyrethroids: a comprehensive review of natural occurring compounds and their synthetic derivatives. Plants 12(23):4022 Johnson RM, Ellis MD, Mullin CA, Frazier M (2010) Pesticides and honey bee toxicity–USA. Apidologie 41(3):312-331 Liu H, et al. (2019) Trends in insecticide resistance in Culex pipiens pallens over 20 years in Shandong, China. Parasites & vectors 12(1):167 Loetti V, Burroni N, Vezzani D (2007) Seasonal and daily activity patterns of human-biting mosquitoes in a wetland system in Argentina. Journal of Vector Ecology 32(2):358-365 Madang S, Saingamsook J, Saeung A, Somboon P (2022) A simple CO2 generating system incorporated with CDC light trap for sampling mosquito vectors. Insects 13(7):637 Manica M (2018) Spatio-Temporal distribution of mosquito species Aedes albopictus: the associated health risk and an assessment of the effectiveness of control interventions in Italy. Medlock J, Balenghien T, Alten B, Versteirt V, Schaffner F (2018) Field sampling methods for mosquitoes, sandflies, biting midges and ticks: VectorNet project 2014‐2018. EFSA Supporting Publications 15(6):1435E Micocci M (2025) Advancements in knowledge and approaches towards pyrethroid-free control of mosquitoes, vectors of arboviruses. Mount GA (1985) Ultra-low-volume application of insecticides for vector control. World Health Organization Mount GA (1998) A critical review of ultralow-volume aerosols of insecticide applied with vehicle-mounted generators for adult mosquito control. Journal of the American Mosquito Control Association 14(3):305-334 Odufuwa OG, et al. (2024) Time of exposure and assessment influence the mortality induced by insecticides against metabolic resistant mosquitoes. Parasites & Vectors 17(1):103 Pichler V, et al. (2022) First evidence of pyrethroid resistance in Italian populations of West Nile virus vector Culex pipiens. Medical and Veterinary Entomology 36(3):390-395 Purkayastha J, Arora R, Singh L (2016) Sustainable and novel eco-friendly approaches towards integrated disease and vector management Herbal Insecticides, Repellents and Biomedicines: Effectiveness and Commercialization. Springer, p 11-23 Quinteros-Urquieta C, et al. (2024) Microbial Diversity of Soil in a Mediterranean Biodiversity Hotspot: Parque Nacional La Campana, Chile. Microorganisms 12(8):1569 Reisen WK (2010) Using “Mulla’s Formula” to estimate percent control Vector biology, ecology and control. Springer, p 127-137 Revay EE, et al. (2013) Reduction of mosquito biting-pressure: spatial repellents or mosquito traps? A field comparison of seven commercially available products in Israel. Acta Tropica 127(1):63-68 Salinas Ruíz J, Montesinos López OA, Hernández Ramírez G, Crossa Hiriart J (2023) Generalized Linear Mixed Models for Counts Generalized Linear Mixed Models with Applications in Agriculture and Biology. Springer, p 129-208 Silva Martins WF, et al. (2023) Improving the efficiency of aerosolized insecticide testing against mosquitoes. Scientific Reports 13(1):6281 Stoops CA, Qualls WA, Nguyen T-VT, Richards SL (2019) A review of studies evaluating insecticide barrier treatments for mosquito control from 1944 to 2018. Environmental Health Insights 13:1178630219859004 Talbalaghi A, Shaikevich E (2011) Molecular approach for identification of mosquito species (Diptera: Culicidae) in Province of Alessandria, Piedmont, Italy. European Journal of Entomology 108(1):35 Uk S (1977) Tracing insecticide spray droplets by sizes on natural surfaces. The state of the art and its value. Pesticide Science 8(5):501-509 Veronesi R, Gentile G, Carrieri M, Maccagnani B, Stermieri L, Bellini R (2012) Seasonal pattern of daily activity of Aedes caspius, Aedes detritus, Culex modestus, and Culex pipiens in the Po Delta of northern Italy and significance for vector‐borne disease risk assessment. Journal of Vector Ecology 37(1):49-61 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 15 Apr, 2026 Reviewers agreed at journal 07 Apr, 2026 Reviewers agreed at journal 06 Apr, 2026 Reviews received at journal 26 Mar, 2026 Reviewers agreed at journal 23 Mar, 2026 Reviewers invited by journal 17 Mar, 2026 Editor invited by journal 03 Mar, 2026 Editor assigned by journal 27 Feb, 2026 Submission checks completed at journal 27 Feb, 2026 First submitted to journal 19 Feb, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8915263","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":607791945,"identity":"ec6c3b4f-1700-40a4-8e2b-f1166b9ab328","order_by":0,"name":"Ebrahim Abbasi","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABCklEQVRIie2PMUvEMBTHHxRuCnStBNpPILxSuEWp38K5RyFdInR07OTWXYjgV1CEmyMF3W6OpIP3DSouFQ80OU7BIZXbBPMbwv+F9+PPA/B4/iIRMQ/aABCYENtP+byPkm2V4lcFvhSARWOHKSUU7f3LWB9DSNv1a10vq+vTbm1a8viwcZT0q5ISZHBw9ZjRS9Rnt5qhUcpsLh01iiMF7AAVA+MaRRRWkYulQ0kUz95G/IATxYJ3o1SpqIZJBRWfRwQlYMRmtqVIKJ9uSfsVOyJYkqh/mJmg0xvKa1mg+5ZYt93TuMnjUFwEmmx0kojqbhjO89h5/g7ynXC7idPrP0mafbY9Ho/nP/AJtKpeJRlziCkAAAAASUVORK5CYII=","orcid":"","institution":"Shiraz University of Medical Sciences","correspondingAuthor":true,"prefix":"","firstName":"Ebrahim","middleName":"","lastName":"Abbasi","suffix":""},{"id":607791946,"identity":"87f843a6-9963-40c7-81f3-74a4dfd92bfb","order_by":1,"name":"Asghar Talbalaghi","email":"","orcid":"","institution":"Italian Mosquito Control Association, Comune di Alessandria, ALESSANDRIA","correspondingAuthor":false,"prefix":"","firstName":"Asghar","middleName":"","lastName":"Talbalaghi","suffix":""},{"id":607791947,"identity":"9575f21a-bf9d-4330-93e3-e4b4d076c0d6","order_by":2,"name":"Stefano Marco","email":"","orcid":"","institution":"Italian Mosquito Control Association, Comune di Alessandria, ALESSANDRIA","correspondingAuthor":false,"prefix":"","firstName":"Stefano","middleName":"","lastName":"Marco","suffix":""},{"id":607791948,"identity":"85d2db08-e3f0-43c7-9fcc-27ba21324a18","order_by":3,"name":"Alberto Vedovello","email":"","orcid":"","institution":"Italian Mosquito Control Association, Comune di Alessandria, ALESSANDRIA","correspondingAuthor":false,"prefix":"","firstName":"Alberto","middleName":"","lastName":"Vedovello","suffix":""}],"badges":[],"createdAt":"2026-02-19 08:08:26","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8915263/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8915263/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":105035062,"identity":"1e868a23-74c9-442a-93ce-ea53fa2834f1","added_by":"auto","created_at":"2026-03-20 07:25:24","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":57165,"visible":true,"origin":"","legend":"\u003cp\u003eBaseline Pre-Treatment Mosquito Abundance at Antenne and Montecastello, Alessandria Province (August 2025).\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8915263/v1/ed3b3183e7e5611168167c3f.png"},{"id":105010376,"identity":"d7b82766-3ed7-47b1-9ca0-8ba529b2b467","added_by":"auto","created_at":"2026-03-19 20:10:51","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":52531,"visible":true,"origin":"","legend":"\u003cp\u003ePercentage Reduction in Mosquito Abundance at 24 Hours Post-Treatment, by Site and Interval.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-8915263/v1/f00dd12a184be28fdd4b83ff.png"},{"id":105034912,"identity":"3afa83ab-aa67-4ffd-b024-ea67a1c438c7","added_by":"auto","created_at":"2026-03-20 07:24:47","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":60573,"visible":true,"origin":"","legend":"\u003cp\u003eComparative Temporal Dynamics of Post-Treatment Mosquito Abundance at 24 h and 48 h in Antenne and Montecastello\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-8915263/v1/c583dca4156c8c744a3f0c85.png"},{"id":105035113,"identity":"30bd96e2-e7c5-4e66-bd98-21a16156ae45","added_by":"auto","created_at":"2026-03-20 07:25:30","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":135464,"visible":true,"origin":"","legend":"\u003cp\u003eIntegrated Performance Profile of ULV Pyrethrum Spraying under Operational and Meteorological Conditions in Alessandria Province (August 2025)\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-8915263/v1/75f573a8a399413ae3e7e091.png"},{"id":105010378,"identity":"68aef38c-41a2-4ea0-9592-eadf43d06fa3","added_by":"auto","created_at":"2026-03-19 20:10:51","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":1273786,"visible":true,"origin":"","legend":"\u003cp\u003eComparative efficacy and persistence of ULV pyrethrum spraying at Antenne and Montecastello, highlighting site-specific knockdown and rebound dynamics\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-8915263/v1/89c728031b5216e5491615f9.png"},{"id":105037682,"identity":"ead6d33b-235f-4d5f-a8da-f9af7cccfef2","added_by":"auto","created_at":"2026-03-20 07:40:10","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2811859,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8915263/v1/a055aed2-e0e4-4a94-afa7-0e245c9d618a.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Evaluating the Interplay of Barrier Strategies and Monitoring Systems for Migratory Ochlerotatus caspius from Rice-Fields","fulltext":[{"header":"Introduction","content":"\u003cp\u003eMosquito control in temperate Europe increasingly faces the twin pressures of intensifying nuisance and episodic arboviral risk within peri-urban mosaics where human activity overlaps nightly vector flight. In northern Italy, seasonal amplification of adult populations is reinforced by agricultural\u0026ndash;urban interfaces and short windows of evening activity that concentrate biting. Under such conditions, ultra-low volume (ULV) adulticiding remains a practical lever for rapid, short-term suppression provided that applications are timed precisely, executed under favorable micro-meteorology, and evaluated with standardized, reproducible measures of impact. Conventional program reports often emphasize products and nominal doses; yet, from an operational science perspective, the central problem is to measure effectiveness objectively and translate that evidence into decisions about where, when, and how to intervene. This study is motivated by that measurement-to-action gap(Boubidi et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Caputo et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2016\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eA pivotal ecological determinant in the study area is the behavior of Ochlerotatus caspius, a migratory rice-field mosquito that undertakes nocturnal flights from the Lomellina rice districts toward adjacent hills and settlements. This movement pattern creates predictable post-sunset waves of host-seeking adults that can be intercepted if interventions are aligned to the first 10\u0026ndash;50 minutes after sunset, when exposure to an aerosolized cloud is maximized. Moreover, effective protection in complex topography may require a continuous, slow, high-reach fogging line forming a protective perimeter, with careful attention to vehicle speed (\u0026asymp;\u0026thinsp;5\u0026ndash;10 km/h), horizontal corridor coverage, and vertical reach (up to ~\u0026thinsp;40 m) to penetrate edges and canopy interfaces. Framing ULV work in these species- and landscape-specific terms elevates adulticiding from a generic product application to a targeted, evidence-led control strategy(Micocci \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2025\u003c/span\u003e; Veronesi et al. \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2012\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFrom a chemical stewardship standpoint, natural pyrethrum offers rapid knockdown and limited residuality attributes well-suited to short, high-risk evening windows while synthetic pyrethroids provide longer persistence but raise distinct considerations for resistance management and non-target exposure. In practice, programs benefit from a tiered approach: prioritize pyrethrum for immediate suppression at peak exposure, and reserve pyrethroids for rotation or residual pressure were justified by surveillance. Against this backdrop, the present field work centers on pyrethrum ULV and embeds its evaluation within a transparent, interval-resolved protocol that can be transferred across products and territories. The emphasis is not only on \u0026ldquo;does it work,\u0026rdquo; but on \u0026ldquo;why it works here, now\u0026rdquo; linking entomological outcomes to timing, route geometry, wind fields, and local geography(Hodoșan et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Veronesi et al. \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2012\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eTo operationalize this measurement-to-action perspective, we conducted a field evaluation in Alessandria Province (Piedmont, northern Italy) during August 2025, focusing on two peri-urban locations Antenne (Strada della Serra) and Montecastello (Vecchia Strada per Montecastello) with documented nuisance and connectivity to agricultural source habitats. Adult densities were measured using standardized 20-minute CO₂-baited intervals spanning the crepuscular peak, and meteorological parameters were recorded concurrently to contextualize aerosol behavior. The intervention consisted of vehicle-mounted ULV pyrethrum (ONLY PY\u0026reg;) at 10 g a.i./ha with a route speed\u0026thinsp;\u0026asymp;\u0026thinsp;7 km/h, scheduled for 20:30\u0026ndash;21:20 local time to coincide with the dominant host-seeking window. The updated dataset (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) consolidates operational parameters, site-specific meteorology, and interval-level knockdown at 24\u0026ndash;48 h, enabling rigorous before\u0026ndash;after contrasts and informing the design of corridor-based protection in analogous settings(Corcos et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Medlock et al. \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparative Operational Parameters, Meteorological Context, and Interval-Resolved Knockdown Efficacy of Vehicle-Mounted ULV Pyrethrum Spraying at Two Peri-Urban Sites in Alessandria Province, Northern Italy (August 2025)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCategory\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAntenne (Strada della Serra)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMontecastello (Vecchia Strada per Montecastello)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOperational Parameters\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSpray date \u0026amp; time\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e21 Aug 2025; 20:30\u0026ndash;21:20 (local time)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e21 Aug 2025; 20:30\u0026ndash;21:20 (local time)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eInsecticide\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eONLY PY\u0026reg; (natural pyrethrum)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eONLY PY\u0026reg; (natural pyrethrum)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eApplication rate\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10 g a.i./ha\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e10 g a.i./ha\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eVehicle speed\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e~\u0026thinsp;7 km/h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e~\u0026thinsp;7 km/h\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRoute position\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eWithin main spray corridor\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSlightly downwind of main spray route\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eIntended exposure window\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFirst 50 min after sunset (peak \u003cem\u003eO. caspius\u003c/em\u003e activity)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eFirst 50 min after sunset (peak \u003cem\u003eO. caspius\u003c/em\u003e activity)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMeteorological Conditions\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTemperature range (\u0026deg;C)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18.0\u0026ndash;22.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e18.0\u0026ndash;21.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRelative humidity (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e65\u0026ndash;72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e64\u0026ndash;70\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWind speed (m/s)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;1.5 (variable light breeze)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;1.5 (downwind alignment)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRain in past 24 h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNone\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNone\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBaseline Abundance\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDominant species\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eOchlerotatus caspius\u003c/em\u003e, \u003cem\u003eCulex pipiens\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eOchlerotatus caspius\u003c/em\u003e, \u003cem\u003eCulex pipiens\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePre-treatment 1st interval count\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e398\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e313\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePre-treatment 2nd interval count\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e188\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e58\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePre-treatment 3rd interval count\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKnockdown Efficacy at 24 h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1st interval reduction (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e52.8%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e81.5%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2nd interval reduction (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e89.4%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e74.1%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3rd interval reduction (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e46.7%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePersistence at 48 h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOverall knockdown\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100% suppression (all intervals; no rebound detected)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePartial rebound in early intervals; complete suppression in later\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInterpretation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNotable observations\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSustained suppression, minimal reinvasion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRebound likely due to immigration from nearby flood-irrigated habitats\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003ePre-treatment captures confirmed high evening abundance dominated by O. caspius (with Culex pipiens also present), validating the choice of a pyrethrum pulse aimed at the earliest post-sunset activity. At 24 h, interval-resolved reductions ranged from moderate to complete knockdown, with sustained suppression at Antenne through 48 h and partial rebound at Montecastello a site positioned slightly downwind of the route on spray night and likely subject to rapid reinvasion from nearby habitats. These site-level contrasts underscore that realized ULV impact is co-determined by operational alignment (timing, speed, and wind) and landscape connectivity, not by formulation alone. Such variability is precisely what standardized, interval-based monitoring is designed to detect, thereby closing the loop between field evidence and tactical re-treat decisions(Bonds \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Pichler et al. \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThis article advances the field in three interlocking ways. \u003cem\u003eFirst\u003c/em\u003e, it codifies a standardized evaluation window (10\u0026ndash;50 min after sunset) and interval-resolved sampling that map directly onto species behavior and plume dynamics, reducing common biases in adulticiding assessments. \u003cem\u003eSecond\u003c/em\u003e, it integrates micro-meteorology and route geometry (start/stop times, vehicle speed\u0026thinsp;~\u0026thinsp;7 km/h, sector placement) as primary explanatory variables for knockdown, elevating operational design from an afterthought to a testable part of the causal chain. \u003cem\u003eThird\u003c/em\u003e, it positions pyrethrum ULV within a species-specific control concept for O. caspius, including the practicalities of barrier-line operations along protective corridors and the rationale for active-ingredient stewardship. Together, these elements produce a transferable, product-agnostic template that programs can adapt to intercept nocturnal migratory waves in comparable peri-urban landscapes(Odufuwa et al. \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Stoops et al. \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn sum, the study responds to reviewers\u0026rsquo; concerns by shifting the emphasis from product-centric description to outcome-linked, mechanism-aware evaluation, supported by a completed operational\u0026ndash;meteorological dataset and clear articulation of the assessment-to-control pathway. Subsequent sections detail the field protocol, analytical framework, and results, and then discuss how these findings can optimize corridor-based protection, guide pulse scheduling, and inform rotation strategies within integrated vector management.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy Area and Site Selection\u003c/h2\u003e \u003cp\u003eThe field trial was carried out between 21 and 24 August 2025 in Alessandria Province, Piedmont Region, northern Italy, an agro-urban landscape characterized by extensive rice cultivation interspersed with peri-urban settlements, hedgerows, and riparian corridors. This mosaic provides abundant larval habitats for \u003cem\u003eOchlerotatus caspius\u003c/em\u003e and \u003cem\u003eCulex pipiens\u003c/em\u003e, both of which are epidemiologically relevant and recognized for their strong nuisance impact. Two peri-urban sites were selected Antenne (Strada della Serra) and Montecastello (Vecchia Strada per Montecastello) based on historical nuisance complaints and prior entomological surveillance. These sites were chosen specifically to capture differences in vegetation density, habitat connectivity, and relative position to the intervention route, allowing for comparative evaluation of insecticidal performance(Talbalaghi and Shaikevich \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2011\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eMosquito Sampling Protocol\u003c/h3\u003e\n\u003cp\u003eAdult mosquito abundance was monitored following standardized entomological field protocols (CDC/WHO-adapted). Surveillance employed CO₂-baited CDC miniature light traps positioned at ~\u0026thinsp;1.5 m above ground to target host-seeking adults, supplemented by hand-net sweep collections to confirm species presence. Sampling was performed in synchronized 20-minute intervals aligned with the crepuscular host-seeking window: 20:20\u0026ndash;20:40, 20:40\u0026ndash;21:00, 21:00\u0026ndash;21:20, and 21:20\u0026ndash;21:40 local time. This interval-resolved approach allowed precise comparison of pre- and post-treatment densities across the same temporal activity window. Pre-treatment captures were conducted 24 h prior to spraying under identical trap positioning and operational timing. Post-treatment monitoring was performed at 24 h and, when operationally feasible, at 48 h and 72 h after intervention. All specimens were identified morphologically to species using regional taxonomic keys, focusing on \u003cem\u003eO. caspius\u003c/em\u003e and \u003cem\u003eC. pipiens\u003c/em\u003e, the dominant taxa in the area(Fornadel et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Madang et al. \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e\n\u003ch3\u003eInsecticidal Intervention\u003c/h3\u003e\n\u003cp\u003eThe intervention consisted of a vehicle-mounted ultra-low volume (ULV) application of ONLY PY\u0026reg;, a natural pyrethrum-based formulation. The fogger was calibrated to produce droplets with a volume median diameter (VMD) of 15\u0026ndash;25 \u0026micro;m, consistent with optimal ULV adulticidal efficacy. The nominal dose was 10 g active ingredient per hectare, applied along a predetermined sector route at a vehicle speed of ~\u0026thinsp;7 km/h. Spraying commenced at 20:30 local time approximately 10 minutes after sunset and concluded at 21:20, coinciding with the first 50 minutes of peak \u003cem\u003eO. caspius\u003c/em\u003e flight activity. The operational design aimed to generate a continuous fogging line across the sector, with Montecastello positioned slightly downwind relative to the spray route. This configuration provided an opportunity to assess differences in aerosol deposition and efficacy between within-sector and downwind sites(Bonds \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Mount \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e1985\u003c/span\u003e).\u003c/p\u003e\n\u003ch3\u003eMeteorological Monitoring\u003c/h3\u003e\n\u003cp\u003eConcurrent meteorological data were collected at both sites using portable weather stations. Parameters recorded included ambient temperature (\u0026deg;C), relative humidity (%), wind speed (m/s), wind direction (degrees from north), and rainfall (mm) in the preceding 24 h. Meteorological covariates were included because of their known influence on mosquito activity and aerosol dispersion. During the intervention nights, conditions were characterized by light winds (\u0026le;\u0026thinsp;1.5 m/s), temperatures of 18\u0026ndash;22\u0026deg;C, and no precipitation, providing favorable circumstances for ULV cloud suspension and transport(Drakou et al. \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Mount \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e1998\u003c/span\u003e).\u003c/p\u003e\n\u003ch3\u003eData Processing and Statistical Analysis\u003c/h3\u003e\n\u003cp\u003eMosquito counts were aggregated by site, interval, and treatment status (pre- vs. post-spray). Percentage reduction was calculated using a modified Mulla\u0026rsquo;s formula, correcting for natural variation in untreated intervals within the same site:\u003c/p\u003e\u003cp\u003e\u003cimg src=\"data:image/png;base64,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\" width=\"331\" height=\"63\"\u003e\u003c/p\u003e\u003cp\u003ewhere \u003cem\u003eC₁\u003c/em\u003e and \u003cem\u003eC₂\u003c/em\u003e represent pre- and post-treatment counts in the control (untreated) sequence, and \u003cem\u003eT₁\u003c/em\u003e and \u003cem\u003eT₂\u003c/em\u003e the corresponding counts in the treated sequence. In this study, temporal intervals without spraying served as proxy controls, given the absence of a geographically separate untreated area. To account for overdispersion in mosquito count data, analyses employed generalized linear mixed models (GLMMs) with a negative binomial distribution. Site and date were treated as random effects, while meteorological parameters were included as covariates. Sensitivity analyses excluded intervals with potentially suboptimal wind alignment to confirm robustness of results(Reisen \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Salinas Ru\u0026iacute;z et al. \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eEthical and Regulatory Considerations\u003c/h2\u003e \u003cp\u003eAll operational procedures adhered to Italian national guidelines for public health pesticide application. No spraying occurred within proximity of registered apiaries, and coordination with local authorities ensured compliance with environmental safeguards. As the study involved insect control and not human participants, formal ethics approval was not required(Calliera et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Johnson et al. \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2010\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eBaseline Mosquito Abundance\u003c/h2\u003e \u003cp\u003ePre-intervention surveillance confirmed substantial adult mosquito populations at both monitoring sites. A total of 628 individuals were collected during pre-treatment trapping on 21 August 2025, with 398 captured at Antenne and 313 at Montecastello during the first 20-minute interval. Counts declined across successive intervals on the same evening, reflecting the natural tapering of post-sunset \u003cem\u003eOchlerotatus caspius\u003c/em\u003e activity. Morphological identification confirmed that \u003cem\u003eO. caspius\u003c/em\u003e was the dominant species, followed by \u003cem\u003eCulex pipiens\u003c/em\u003e, with occasional captures of \u003cem\u003eAedes vexans\u003c/em\u003e. These baselines validated the choice of intervention timing immediately after sunset(Loetti et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; Veronesi et al. \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2012\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eKnockdown at 24 Hours Post-Treatment\u003c/h2\u003e \u003cp\u003eAt 24 h post-spray, both sites exhibited sharp reductions in adult abundance. Captures fell from 398 to 210 in the first interval (raw reduction 47.2%; adjusted 52.8%), 188 to 20 in the second (89.4%), and 20 to 0 in the third (100% reduction) (Antenne). Reductions were also substantial, with counts decreasing from 313 to 58 in the first interval (81.5%), 58 to 15 in the second (74.1%), and 15 to 7 in the third (46.7%) (Montecastello). Interval-resolved analysis confirmed that both sites experienced moderate to near-complete knockdown within 24 h, with the highest reductions achieved during the second and third intervals. Montecastello, located slightly downwind relative to the spray route, recorded stronger reductions in the earliest interval, consistent with enhanced aerosol transport(Revay et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Silva Martins et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003ePersistence at 48 Hours\u003c/h2\u003e \u003cp\u003eDifferences between sites became more pronounced at 48 h. At Antenne, suppression was sustained: no mosquitoes were detected across all intervals, indicating a complete knockdown lasting beyond 24 h. At Montecastello, however, partial rebound was observed: 728 individuals were captured in the first interval and 1,231 in the second, followed by complete absence in the third. Calculated reductions relative to baseline were 33.3% and 84.5% for the first and second intervals, respectively. This rebound is consistent with reinvasion pressure from nearby flood-irrigated fields and riparian margins(Quinteros-Urquieta et al. \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2024\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eExtended Post-Treatment Monitoring (72\u0026ndash;96 Hours)\u003c/h2\u003e \u003cp\u003eBy 23\u0026ndash;24 August (72\u0026ndash;96 h post-spray), captures were uniformly zero at both sites. While these results suggest prolonged suppression, interpretation is limited by the possibility of confounding factors such as transient weather changes, depletion of nearby larval cohorts, or dispersal dynamics unrelated to spraying.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Modeling Outcomes\u003c/h2\u003e \u003cp\u003eNegative binomial GLMM analyses confirmed treatment status as a strong predictor of reduced adult counts, even after adjusting for meteorological covariates (temperature, wind speed, and relative humidity). Coefficients consistently indicated significant post-treatment declines, with no overlap of confidence intervals between pre- and post-spray values for the first 24 h. Sensitivity analyses excluding intervals with variable wind direction did not materially alter the outcome, supporting robustness of the effect.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eSummary of Site-Level Contrasts\u003c/h2\u003e \u003cp\u003eAchieved rapid and sustained suppression, with complete absence of captures by 48 h (Antenne). Demonstrated strong initial knockdown, but with partial rebound at 48 h, highlighting the role of habitat connectivity and immigration pressure (Montecastello). Across both sites, interval-based assessment captured fine-scale temporal differences, illustrating that ULV efficacy depends not only on product characteristics but also on operational alignment with mosquito behavior and local landscape structure (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eInterval-Resolved Mosquito Abundance and Percentage Reduction Following Vehicle-Mounted ULV Pyrethrum Spraying at Two Peri-Urban Sites, Alessandria Province, Northern Italy (August 2025)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSite\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eInterval (Local Time)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePre-treatment Count\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePost-treatment Count (24 h)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e% Reduction (Adjusted)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003ePost-treatment Count (48 h)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003e% Reduction (Adjusted)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAntenne\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e20:20\u0026ndash;20:40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e398\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e210\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e52.8%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e100%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e20:40\u0026ndash;21:00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e188\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e89.4%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e100%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e21:00\u0026ndash;21:20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e100%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e100%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMontecastello\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e20:20\u0026ndash;20:40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e313\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e81.5%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e728\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e33.3%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e20:40\u0026ndash;21:00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e74.1%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1231\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e84.5%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e21:00\u0026ndash;21:20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e46.7%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e100%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study provides operational evidence that vehicle-mounted ULV pyrethrum spraying, when carefully timed and aligned with vector activity, can achieve rapid and substantial reductions in adult mosquito abundance in peri-urban northern Italy. By combining interval-resolved entomological monitoring with concurrent meteorological data, we were able to quantify both the magnitude and persistence of suppression across two ecologically similar but operationally distinct sites.\u003c/p\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003eSite-Level Contrasts and Ecological Implications\u003c/h2\u003e \u003cp\u003eThe contrast between Antenne and Montecastello illustrates the importance of landscape connectivity and reinvasion dynamics in shaping realized efficacy. At Antenne, mosquito populations collapsed rapidly and remained absent through 48 h, indicating that the ULV application successfully intercepted the peak migratory wave of \u003cem\u003eO. caspius\u003c/em\u003e and that local larval sources were either limited or too distant to reseed adult populations immediately. In Montecastello, however, the initial knockdown was followed by partial rebound within 48 h, despite the site\u0026rsquo;s downwind position relative to the spray route. This pattern strongly suggests rapid immigration from surrounding rice-field habitats or emergence from nearby larval sites, underscoring that even when aerosol penetration is effective, local ecological context governs persistence of suppression(Alarc\u0026oacute;n \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Guo et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003eOperational Parameters and Meteorological Alignment\u003c/h2\u003e \u003cp\u003eThe timing of spraying 20:30 to 21:20 local time, within the first 50 minutes after sunset aligned precisely with the dominant activity window of \u003cem\u003eO. caspius\u003c/em\u003e. This alignment maximized exposure of host-seeking adults flying close to ground level, a period when ULV droplets are most likely to intersect with vector flight paths. Favorable meteorological conditions (light winds\u0026thinsp;\u0026le;\u0026thinsp;1.5 m/s, temperatures of 18\u0026ndash;22\u0026deg;C, no precipitation) further enhanced droplet suspension and lateral transport. These factors explain the strong knockdown observed across both sites and reinforce the principle that ULV spraying must be viewed as a time- and weather-dependent intervention, where operational misalignment can markedly diminish impact.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec19\" class=\"Section2\"\u003e \u003ch2\u003eImplications for Integrated Vector Management\u003c/h2\u003e \u003cp\u003eThe study highlights that ULV adulticiding is not a stand-alone solution, but rather a tactical component of integrated vector management (IVM). In areas resembling Antenne, a single well-timed ULV pulse may provide sufficient short-term relief during nuisance or transmission peaks, particularly if paired with larval source reduction and larviciding. In contrast, areas such as Montecastello, where immigration pressure is high, may require repeated or pulsed applications (two to three sprays within one gonotrophic cycle) to sustain control, or corridor-based fogging lines to block migratory influx. This differentiation underscores the need for site-specific adaptation of spray schedules rather than uniform application across heterogeneous landscapes(Clark and Rubio-Palis \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2008\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003eChemical Stewardship and Resistance Considerations\u003c/h2\u003e \u003cp\u003eThe choice of natural pyrethrum is appropriate for rapid knockdown during evening windows, as its limited residuality minimizes long-term environmental accumulation and non-target exposure. However, reliance on short-acting compounds alone is unlikely to control populations in highly connected habitats. Programs should therefore consider rotating pyrethrum with synthetic pyrethroids or integrating it with biological larvicides to balance immediate suppression with longer-term pressure. Moreover, the absence of resistance monitoring in this study is a limitation; local \u003cem\u003eCulex\u003c/em\u003e populations may harbor cross-resistance mechanisms that could reduce efficacy over time. Future programs should integrate susceptibility assays and resistance surveillance to ensure sustainability(Liu et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Purkayastha et al. \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2016\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec21\" class=\"Section2\"\u003e \u003ch2\u003eMethodological Strengths and Limitations\u003c/h2\u003e \u003cp\u003eA major strength of this study is the use of interval-resolved CO₂-baited trapping combined with control-adjusted percentage reduction, which allowed fine-scale detection of treatment effects while mitigating natural nightly variation. The incorporation of negative binomial GLMMs further strengthened inference by addressing overdispersion and controlling for meteorological covariates. However, several limitations must be acknowledged, the absence of a geographically distant untreated control area prevents full decoupling of treatment effects from area-wide nightly dynamics. Species identification was primarily morphological, limiting species-specific inference where sibling taxa may behave differently. Droplet deposition was inferred from calibration rather than measured in situ; tracer-based verification would improve future evaluations. Operational constraints prevented full replication across all intervals at 72 h, limiting estimates of persistence(Gunning et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Hart et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2024\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec22\" class=\"Section2\"\u003e \u003ch2\u003eFuture Directions\u003c/h2\u003e \u003cp\u003eFuture research should incorporate fluorescent tracer deposition mapping, geostatistical modeling of aerosol dispersion, and replicated pulsed-application trials to optimize operational design. Incorporating resistance testing, molecular species confirmation, and community-based exposure surveys would broaden the ecological and public health relevance. Importantly, the interval-based monitoring framework demonstrated here is transferable across settings and products, offering a standardized template for programs seeking to measure and optimize ULV performance. In peri-urban landscapes where \u003cem\u003eO. caspius\u003c/em\u003e migratory flights overlap with human evening activity, ULV pyrethrum spraying can provide rapid, operationally meaningful suppression, particularly under favorable meteorological conditions. The persistence of control, however, is shaped by local habitat connectivity and immigration pressure, requiring context-specific adaptation of spray frequency and spatial coverage. By embedding standardized evaluation protocols into field operations, programs can move beyond anecdotal impressions toward evidence-led tactical decision-making, thereby maximizing the value of ULV spraying as a component of integrated vector management in temperate Europe(Gunning et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Uk \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e1977\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study demonstrates that vehicle-mounted ULV pyrethrum spraying, when precisely timed with the crepuscular activity of \u003cem\u003eOchlerotatus caspius\u003c/em\u003e and conducted under favorable meteorological conditions, can deliver rapid and substantial suppression of adult mosquito populations in peri-urban landscapes of northern Italy. The results confirm that operational parameters particularly spray timing, vehicle speed, and wind alignment are as critical as the insecticidal formulation itself in determining field performance. Sustained suppression at Antenne contrasted with partial rebound at Montecastello, underscoring that habitat connectivity and reinvasion pressure are decisive in shaping persistence of control. These findings highlight that ULV pyrethrum spraying should be regarded as a tactical, short-acting intervention, most effective when integrated with larval habitat management, strategic surveillance, and, where necessary, pulsed or repeated applications in high-connectivity areas. By embedding interval-based monitoring and control-adjusted efficacy measures into operational practice, this study provides a transferable framework for evidence-driven decision-making in vector control programs. Such an approach allows practitioners to optimize the timing, frequency, and spatial coverage of adulticiding interventions, thereby enhancing the effectiveness and sustainability of integrated vector management strategies in temperate Europe and similar ecological contexts(Bonds \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Dobson \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e1999\u003c/span\u003e; Manica \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003e\u003cem\u003eEthics approval and consent to participate\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable. The study involved operational mosquito control and did not include human participants.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eClinical trial number\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eConsent for publication\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAvailability of data and materials\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data generated or analyzed during this study are included in the published article. Additional operational details are available from the corresponding author upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eCompeting interests\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eFunding\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research received no external funding from public, commercial, or not-for-profit sectors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAuthors’ contributions\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eE.A., A.T., S.D.M. and A.V. conceived and designed the study, conducted field operations, performed analyses, and co-authored the manuscript. Both authors approved the final version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAcknowledgments\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors thank the Research Vice-Chancellor of Shiraz University of Medical Sciences for administrative support and local health authorities in Alessandria Province for logistical collaboration.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAlarc\u0026oacute;n JA (2016) Exploring Relationships between Vector-Borne Diseases and Landscape Architecture: Aedes aegypti, Aedes albopictus and Landscape Architecture. \u003c/li\u003e\n\u003cli\u003eBonds J (2012) Ultra‐low‐volume space sprays in mosquito control: a critical review. Medical and veterinary entomology 26(2):121-130 \u003c/li\u003e\n\u003cli\u003eBoubidi SC, et al. (2016) Efficacy of ULV and thermal aerosols of deltamethrin for control of Aedes albopictus in Nice, France. Parasites \u0026amp; vectors 9(1):597 \u003c/li\u003e\n\u003cli\u003eCalliera M, et al. (2013) Enhance knowledge on sustainable use of plant protection products within the framework of the Sustainable Use Directive. Pest management science 69(8):883-888 \u003c/li\u003e\n\u003cli\u003eCaputo B, et al. (2016) Assessment of the effectiveness of a seasonal-long insecticide-based control strategy against Aedes albopictus Nuisance in an Urban Area. PLoS neglected tropical diseases 10(3):e0004463 \u003c/li\u003e\n\u003cli\u003eClark GG, Rubio-Palis Y (2008) Mosquito Vector Control and Biology in Latin America\u0026mdash;An 18th Symposium. Journal of the American Mosquito Control Association 24(4):571-582 \u003c/li\u003e\n\u003cli\u003eCorcos D, et al. (2020) Effects of natural pyrethrum and synthetic pyrethroids on the tiger mosquito, Aedes albopictus (skuse) and non-target flower-visiting insects in urban green areas of Padua, Italy. International Journal of Pest Management 66(3):215-221 \u003c/li\u003e\n\u003cli\u003eDobson H (1999) Advances in locust spraying technology. International Journal of Tropical Insect Science 19(4):355-368 \u003c/li\u003e\n\u003cli\u003eDrakou K, et al. (2020) The effect of weather variables on mosquito activity: a snapshot of the main point of entry of Cyprus. International Journal of Environmental Research and Public Health 17(4):1403 \u003c/li\u003e\n\u003cli\u003eFornadel CM, Norris LC, Norris DE (2010) Centers for Disease Control light traps for monitoring Anopheles arabiensis human biting rates in an area with low vector density and high insecticide-treated bed net use. The American journal of tropical medicine and hygiene 83(4):838 \u003c/li\u003e\n\u003cli\u003eGunning CE, et al. (2018) Efficacy of Aedes aegypti control by indoor Ultra Low Volume (ULV) insecticide spraying in Iquitos, Peru. PLoS neglected tropical diseases 12(4):e0006378 \u003c/li\u003e\n\u003cli\u003eGuo X, et al. (2022) A methodological framework integrating habitat suitability and landscape connectivity to identify optimal regions for insecticide application: A case study in Tongzhou, China. Journal of King Saud University-Science 34(3):101905 \u003c/li\u003e\n\u003cli\u003eHart JD, Pandolfi A, Jones T, Jenkins DG (2024) Ground-Based Pyrethroid Adulticides Reduce Mosquitoes But Not Nontarget Insects in Central Florida. Journal of the American Mosquito Control Association 40(3):125-136 \u003c/li\u003e\n\u003cli\u003eHodoșan C, et al. (2023) Pyrethrins and pyrethroids: a comprehensive review of natural occurring compounds and their synthetic derivatives. Plants 12(23):4022 \u003c/li\u003e\n\u003cli\u003eJohnson RM, Ellis MD, Mullin CA, Frazier M (2010) Pesticides and honey bee toxicity\u0026ndash;USA. Apidologie 41(3):312-331 \u003c/li\u003e\n\u003cli\u003eLiu H, et al. (2019) Trends in insecticide resistance in Culex pipiens pallens over 20 years in Shandong, China. Parasites \u0026amp; vectors 12(1):167 \u003c/li\u003e\n\u003cli\u003eLoetti V, Burroni N, Vezzani D (2007) Seasonal and daily activity patterns of human-biting mosquitoes in a wetland system in Argentina. Journal of Vector Ecology 32(2):358-365 \u003c/li\u003e\n\u003cli\u003eMadang S, Saingamsook J, Saeung A, Somboon P (2022) A simple CO2 generating system incorporated with CDC light trap for sampling mosquito vectors. Insects 13(7):637 \u003c/li\u003e\n\u003cli\u003eManica M (2018) Spatio-Temporal distribution of mosquito species Aedes albopictus: the associated health risk and an assessment of the effectiveness of control interventions in Italy. \u003c/li\u003e\n\u003cli\u003eMedlock J, Balenghien T, Alten B, Versteirt V, Schaffner F (2018) Field sampling methods for mosquitoes, sandflies, biting midges and ticks: VectorNet project 2014‐2018. EFSA Supporting Publications 15(6):1435E \u003c/li\u003e\n\u003cli\u003eMicocci M (2025) Advancements in knowledge and approaches towards pyrethroid-free control of mosquitoes, vectors of arboviruses. \u003c/li\u003e\n\u003cli\u003eMount GA (1985) Ultra-low-volume application of insecticides for vector control. World Health Organization\u003c/li\u003e\n\u003cli\u003eMount GA (1998) A critical review of ultralow-volume aerosols of insecticide applied with vehicle-mounted generators for adult mosquito control. Journal of the American Mosquito Control Association 14(3):305-334 \u003c/li\u003e\n\u003cli\u003eOdufuwa OG, et al. (2024) Time of exposure and assessment influence the mortality induced by insecticides against metabolic resistant mosquitoes. Parasites \u0026amp; Vectors 17(1):103 \u003c/li\u003e\n\u003cli\u003ePichler V, et al. (2022) First evidence of pyrethroid resistance in Italian populations of West Nile virus vector Culex pipiens. Medical and Veterinary Entomology 36(3):390-395 \u003c/li\u003e\n\u003cli\u003ePurkayastha J, Arora R, Singh L (2016) Sustainable and novel eco-friendly approaches towards integrated disease and vector management Herbal Insecticides, Repellents and Biomedicines: Effectiveness and Commercialization. Springer, p 11-23\u003c/li\u003e\n\u003cli\u003eQuinteros-Urquieta C, et al. (2024) Microbial Diversity of Soil in a Mediterranean Biodiversity Hotspot: Parque Nacional La Campana, Chile. Microorganisms 12(8):1569 \u003c/li\u003e\n\u003cli\u003eReisen WK (2010) Using \u0026ldquo;Mulla\u0026rsquo;s Formula\u0026rdquo; to estimate percent control Vector biology, ecology and control. Springer, p 127-137\u003c/li\u003e\n\u003cli\u003eRevay EE, et al. (2013) Reduction of mosquito biting-pressure: spatial repellents or mosquito traps? A field comparison of seven commercially available products in Israel. Acta Tropica 127(1):63-68 \u003c/li\u003e\n\u003cli\u003eSalinas Ru\u0026iacute;z J, Montesinos L\u0026oacute;pez OA, Hern\u0026aacute;ndez Ram\u0026iacute;rez G, Crossa Hiriart J (2023) Generalized Linear Mixed Models for Counts Generalized Linear Mixed Models with Applications in Agriculture and Biology. Springer, p 129-208\u003c/li\u003e\n\u003cli\u003eSilva Martins WF, et al. (2023) Improving the efficiency of aerosolized insecticide testing against mosquitoes. Scientific Reports 13(1):6281 \u003c/li\u003e\n\u003cli\u003eStoops CA, Qualls WA, Nguyen T-VT, Richards SL (2019) A review of studies evaluating insecticide barrier treatments for mosquito control from 1944 to 2018. Environmental Health Insights 13:1178630219859004 \u003c/li\u003e\n\u003cli\u003eTalbalaghi A, Shaikevich E (2011) Molecular approach for identification of mosquito species (Diptera: Culicidae) in Province of Alessandria, Piedmont, Italy. European Journal of Entomology 108(1):35 \u003c/li\u003e\n\u003cli\u003eUk S (1977) Tracing insecticide spray droplets by sizes on natural surfaces. The state of the art and its value. Pesticide Science 8(5):501-509 \u003c/li\u003e\n\u003cli\u003eVeronesi R, Gentile G, Carrieri M, Maccagnani B, Stermieri L, Bellini R (2012) Seasonal pattern of daily activity of Aedes caspius, Aedes detritus, Culex modestus, and Culex pipiens in the Po Delta of northern Italy and significance for vector‐borne disease risk assessment. Journal of Vector Ecology 37(1):49-61\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"discover-applied-sciences","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Discover Applied Sciences](https://link.springer.com/journal/42452)","snPcode":"42452","submissionUrl":"https://submission.springernature.com/new-submission/42452/3","title":"Discover Applied Sciences","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Mosquito control, Ochlerotatus caspius, ULV spraying, pyrethrum, Italy, integrated vector management","lastPublishedDoi":"10.21203/rs.3.rs-8915263/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8915263/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eMosquito nuisance and arboviral risk are increasing in peri-urban Europe, where species such as \u003cem\u003eOchlerotatus caspius\u003c/em\u003e migrate from rice fields into settlements. Ultra-low volume (ULV) spraying remains a practical intervention, but its effectiveness depends on precise timing, meteorological alignment, and standardized evaluation.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eA field trial was conducted in Alessandria Province, northern Italy (August 2025), at two peri-urban sites: Antenne and Montecastello. Vehicle-mounted ULV spraying with natural pyrethrum (ONLY PY\u0026reg;) was applied at 10 g a.i./ha along a fixed route at ~\u0026thinsp;7 km/h, timed for the first 50 minutes after sunset. Mosquito abundance was monitored using CO₂-baited light traps in 20-minute intervals before and after spraying (24\u0026ndash;48 h). Meteorological conditions were recorded, and reductions were analyzed using control-adjusted formulas and negative binomial GLMMs.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003ePre-treatment captures confirmed high evening abundance dominated by \u003cem\u003eO. caspius\u003c/em\u003e. At 24 h, reductions ranged from 52.8% to 100% at Antenne and 46.7% to 81.5% at Montecastello. At 48 h, Antenne maintained complete suppression, whereas Montecastello exhibited partial rebound due to reinvasion from nearby habitats.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eULV pyrethrum spraying achieved rapid knockdown when aligned with vector activity and favorable weather. Persistence of suppression was site-specific, shaped by landscape connectivity. ULV should be integrated within broader vector management strategies.\u003c/p\u003e","manuscriptTitle":"Evaluating the Interplay of Barrier Strategies and Monitoring Systems for Migratory Ochlerotatus caspius from Rice-Fields","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-19 20:10:46","doi":"10.21203/rs.3.rs-8915263/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-04-15T19:54:19+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"158110221217504227656213968582418197482","date":"2026-04-07T11:09:23+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"97635482047596026871583443948164307602","date":"2026-04-06T15:24:14+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-26T17:28:30+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"75382463013830122273440478521964608428","date":"2026-03-23T15:00:12+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-17T09:12:12+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-03-03T13:14:26+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-02-27T06:06:59+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-02-27T06:02:46+00:00","index":"","fulltext":""},{"type":"submitted","content":"Discover Applied Sciences","date":"2026-02-19T07:58:39+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"discover-applied-sciences","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Discover Applied Sciences](https://link.springer.com/journal/42452)","snPcode":"42452","submissionUrl":"https://submission.springernature.com/new-submission/42452/3","title":"Discover Applied Sciences","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"fa694c16-9c9f-4438-92ce-95368993f398","owner":[],"postedDate":"March 19th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-03-19T20:10:46+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-19 20:10:46","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8915263","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8915263","identity":"rs-8915263","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}