Widening range of thrips in open-field rose cultivation: three species newly identified as pests in southern India

Widening range of thrips in open-field rose cultivation: three species newly identified as pests in southern India | 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 Widening range of thrips in open-field rose cultivation: three species newly identified as pests in southern India Prakya Sreerama Kumar, Rajan Remani Rachana, Bellapu Amarendra, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7928863/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Rose is a high-value ornamental crop widely cultivated under both open-field and protected conditions in India. Thrips have emerged as a major pest group, causing significant aesthetic and economic damage. This study investigated the species composition of thrips infesting open-field roses in southern India, along with associated damage symptoms and morphological diagnostics. Five species were identified: Frankliniella occidentalis , Retithrips syriacus , Scirtothrips dorsalis , Thrips palmi and Thrips parvispinus . Of these, R. syriacus , T. palmi and T. parvispinus represent newly recorded species on roses in India. The study did not reveal a reliable correlation between specific thrips species and identifiable symptom patterns. The presence of invasive, polyphagous species such as F. occidentalis and T. parvispinus poses a threat to other susceptible crops, with roses potentially serving as a reservoir. There remains a significant risk of heightened losses should these species establish themselves in roses cultivated under protected environments such as greenhouses and polyhouses. The findings underscore the importance of continuous monitoring and species-specific integrated pest management strategies to mitigate future economic risks. Frankliniella occidentalis invasive thrips new host Thrips parvispinus Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Introduction In India, roses ( Rosa spp.) are cultivated both in open fields and under protected environments such as greenhouses and polyhouses, with a number of insects, mites and diseases emerging as significant constraints in both settings. Thrips (Thysanoptera) in particular are major pests, causing economic losses ranging from 28 to 95 per cent (Gahukar 2003 ), in addition to aesthetic deterioration. With their asymmetrical rasping-sucking mouthparts, thrips pierce plant tissue and extract liquid food, thus inflicting various forms of damage, including silvering and upward curling of leaves; browning and premature wilting of petals; as well as scarring, bronzing and deformation of flowers and flower buds (Duraimurugan and Jagadish 2011 ; Rachana et al. 2018 ). Adult thrips feed on flower petals, causing silvery-white or brown streaks, which ultimately lead to the loss of flower colour (Rachana et al. 2018 ) and thus the ornamental value of roses. Thrips undergo multiple generations per year and tend to aggregate in concealed areas, making insecticide-based management challenging. When present in low numbers, thrips on roses must be detected and managed, as even a few on the flowers can cause petal discoloration (Bertaux et al. 2003 ). Given their rapid life cycle and ability to develop resistance to chemical pesticides, thrips pose a considerable challenge to rose growers. Although comprehensive taxonomic research on thrips species affecting roses in India remains limited, several previous studies have identified the infestation of Frankliniella occidentalis (Pergande), Frankliniella schultzei (Trybom), Scirtothrips dorsalis (Hood) and Thrips hawaiiensis (Morgan) (Rachana et al., 2018 ; Ranaware et al., 2024 ; Suman et al., 2024 ). Conversely, the majority of pest management studies have largely hypothesized that S. dorsalis is the predominant species in Indian rose cultivation. Thrips can disperse through flight, infested planting material or wind currents (Mound 1983 ), and can successfully establish in new areas if suitable environmental conditions are present (McDonald et al. 1998 ). Therefore, precise identification of pest species is essential for formulating effective management strategies tailored to the targeted pests. Researchers can detect subtle variations in pest species composition by systematically monitoring multiple pest species within a crop. This approach is particularly crucial for invasive thrips, which can disperse over extensive distances either through natural mechanisms or inadvertent human activity (Morse and Hoddle 2006 ). Reports of two invasive thrips species, F. occidentalis and Thrips parvispinus (Karny) (Tyagi and Kumar 2015 ; Tyagi et al. 2015 ), in India require special attention, as both are potential polyphagous plant pests. Additionally, F. occidentalis is known to act as a vector for Orthotospoviruses (Rachana et al. 2022 ). In 2021, chilli farmers in Telangana, a southern state of India, mistakenly identified a T. parvispinus outbreak as a mite infestation. This misdiagnosis led to the use of inappropriate pesticides, causing a thrips flare-up that reduced yields by nearly 80 per cent (Verma et al. 2022 ). Thus, incorrect identification of emerging pest populations can have unforeseen consequences, particularly concerning biosafety and management (Armstrong and Ball 2005 ; Venette and Hutchison 2021 ). The purposes of this article are to inspect and document the thrips species composition infesting rose in southern India, to describe the symptoms of damage, and to illustrate the significant diagnostic characteristics of the species collected on that host. Field collection, mounting and identification of thrips specimens Between January 2019 and December 2024, more than 400 thrips specimens were collected from various rose cultivars cultivated across the southern Indian states of Andhra Pradesh, Karnataka, and Tamil Nadu. Roses cultivated under protected conditions within polyhousese were also sampled, in addition to those grown in open fields. Sampling focused on leaves exhibiting characteristic tissue responses commonly associated with thrips infestation, such as puckering, crinkling, twisting, curling, streaking, malformation and discolouration, in order to identify the causative thrips species. Similarly, flower buds and fully opened flowers displaying visible symptoms of damage or suspected to contain thrips were also collected. In polyhouses, developing flower buds enclosed in soft, elastic protective sleeves (flower-bud nets) — used to prevent premature opening, pest damage, mechanical injury and petal ruffling caused by wind or handling — and exhibiting brown streaks and morphological abnormalities were also collected for assessment. Adult thrips were observed on leaf surfaces, within leaf axils, inside curled leaves and beneath flower calyxes. They were extracted in the field by gently tapping infested leaves over a white plastic tray. In instances where mixed-species infestation was suspected, rose twigs, flower buds and flowers harbouring thrips immatures and eggs were enclosed in transparent polypropylene bags (Sreerama Kumar et al., 2024 ) and maintained under laboratory conditions until adult emergence. Prior to bagging, all symptomatic plant material was meticulously examined under a stereozoom microscope (Nikon SMZ800) to exclude the presence of other arthropod pests occupying the same ecological niche. Thrips specimens were preserved in vials containing AGA medium (9 parts 10% ethyl alcohol, 1 part glacial acetic acid and 1 ml Triton X-100 per 1,000 ml of the mixture) for further processing. From the preservative medium, specimens were first immersed in 2% NaOH for 30 min, then transferred to 60% ethyl alcohol for 24 h, followed by dehydration through a graded series of 70–100% ethyl alcohol washes. After clearing in clove oil for 5–10 min, specimens were individually mounted in Canada balsam on microscope slides and dried at 45°C for 30 min in an oven. The slides were examined using an Olympus BX51 microscope (4× and 10×), and photomicrographs of taxonomically significant characters were captured with an Olympus DP23 camera attached to the microscope. Final figure compositions were created using Adobe Photoshop CS2 software. The specimens were identified to species level using the taxonomic keys provided by Amutha and Rachana ( 2023 ) and Wilson ( 1975 ). Voucher specimens were deposited in the National Insect Museum at the Indian Council of Agricultural Research – National Bureau of Agricultural Insect Resources (ICAR–NBAIR), Bengaluru, India. Thrips species composition Taxonomic studies identified five species of thrips belonging to the suborder Terebrantia (Thysanoptera): Frankliniella occidentalis , commonly known as the western flower thrips; Retithrips syriacus (Mayet), the black vine thrips; Scirtothrips dorsalis , the chilli thrips; Thrips palmi Karny, the melon thrips; and Thrips parvispinus , referred to as the Southeast Asian thrips. While R. syriacus belongs to the subfamily Panchaetothripinae, the other four are classified under the subfamily Thripinae, all within the family Thripidae. Among the five, S. dorsalis was the only thrips found infesting roses in the surveyed polyhouses in Bengaluru Urban and Ramanagara districts in Karnataka. It was also found to infest open-field rose in Bengaluru Rural and Kolar districts of the same state. Frankliniella occidentalis, T. palmi and T. parvispinus along with S. dorsalis were found simultaneously infesting rose at Kalahalli in Bengaluru Rural district. Retithrips syriacus was observed as a pest of rose in Araku Valley of Alluri Sitharama Raju district in Andhra Pradesh. Damage symptoms Within polyhouses, S. dorsalis was observed on rose leaves, leaf axils, beneath calyxes and nestled within petals, inflicting significant damage to both foliage and blooms. The characteristic injuries caused by this species were recognized as typical indicators of thrips infestation. Young flushes infested by thrips exhibited scarring, yellow blotches, brown streaks and upward curling of leaves (Figs. 1 & 2 ). Feeding during the flower bud initiation stage resulted in visible damage, especially to the outer sepals, leading to malformed buds that either opened incompletely or failed to develop (Fig. 3 ). Developing flower buds enclosed in flower-bud nets were found to be vulnerable to infestation by S. dorsalis in polyhouse conditions (Fig. 4 ). Under open field conditions, thrips activity on petals caused silvery-white or brown streaks, leading to loss of natural coloration, formation of irregular brown patches, and browning along the edges. Rose bud sepals exhibited scabby brown scars (Figs. 5 & 6 ). However, no distinct symptoms could be consistently linked to any specific thrips species in open-field roses. Diagnostic key to the reported species Forewings with calluses (Fig. 8G); body short and stout (Fig. 8A)…………...…... syriacus Forewings without callosities; body normal………………………………..…………………2 Antennae 8 segmented (Fig. 7C) ........................................................................................ 3 Antennae 7 segmented (Fig. 10B) ………………………………………………………….... 4 Abdominal tergites with closely spaced microtrichial rows laterally; forewing veins with non-uniform setal rows (Fig. 9F)……………………….………………...……..… dorsalis Abdominal tergites without lateral microtrichial rows; forewing veins with uniform setal rows (Fig. 7J) ………………………..………………………………………… occidentalis Metanotal sculpture striate longitudinally (Fig. 10C); abdominal tergite VIII with complete posteromarginal comb (Fig. 10G); abdominal sternites without discal setae……………………………………………………………………..……….......... palmi Metanotal sculpture reticulate (Fig. 11E); abdominal tergite VIII without complete posteromarginal comb (Fig. 11F); abdominal sternites with discal setae……………….………...……………………………………….................. parvispinus Diagnostic characters of the thrips species Diagnostic characters of F. occidentalis , R. syriacus , S. dorsalis , T. palmi and T. parvispinus are depicted in Figs. 7 , 8 , 9 , 10 and 11 , and the morphological characters indicated in those figures are adapted from Rachana and Varatharajan 2018 , Wilson 1975 and Sreerama Kumar et al. 2024 , respectively. These diagnostic characters are as follows; Frankliniella occidentalis ( Fig. 7 ) Diagnosis. Body yellow with median brown patches on abdominal tergites; leg; fore wing shaded. Head with ocellar pair III arising between parallel tangent of fore and hind ocelli; six pairs of postocular setae, pair IV distinctively longer than others. Pronotum with four small setae between the major anteromarginal setae. Metanotum reticulate; campaniform sensilla present. Abdominal tergite VIII with irregular comb of microtrichia. Retithrips syriacus ( Fig. 8 ) Diagnosis. Body blackish brown, reticulated polygonally, legs brown except yellow tarsi. Antennae 8 segmented. Forewing apical half with 3 calluses between the costal and anterior veins; anterior margin without fringe cilia, posterior fringe cilia straight. Abdominal tergites reticulate; I with constricted posterior submedian areas, II-X with reticulate median depressed area, III-VII each with a submedian pair of toothed comb on posterior margin, VIII with complete posteromarginal comb of long microtrichia. Scirtothrips dorsalis ( Fig. 9 ) Diagnosis. Body yellow, median brown shades on abdominal tergites III–VII, dark antecostal ridges on abdominal tergites and sternites. Interocellar setae pair arise between hind ocelli. Median setae pair on metanotum placed well behind anterior margin. Forewing second vein with 2 setae. Lateral tergal microtrichial fields on abdomen with 3 discal setae; tergite VIII with complete posteromarginal comb. Abdominal sternites with microtrichia extending across median area but limited to posterior half. Thrips palmi ( Fig. 10 ) Diagnosis. Yellow body. Metanotum having longitudinal lines converging posteriorly, with anterior transverse lines; median pair of setae placed well behind anterior margin, with campaniform sensilla. Forewing first vein with 3 distal setae. Abdominal tergite VIII with posteromarginal comb complete. Abdominal sternites without discal setae. Thrips parvispinus ( Fig. 11 ) Diagnosis. Body brown; forewing brown with base pale; legs yellow. Interocellar setae pair placed on anterior margins of ocellar triangle. Metanotum reticulate medially; median setae situated behind anterior margin; campaniform sensilla absent. Forewing first and second veins with regular rows of setae. Posteromarginal comb on abdominal tergite VIII absent, a few microtrichia present laterally. Discal setae absent on abdominal sternites II and VII, III–VI with about 6–12 discal setae arranged irregularly. Discussion Most studies in India have assumed S. dorsalis to be the sole thrips species affecting roses. With its broad host range and tendency to attack both leaves and flowers, S. dorsalis might pose a significantly greater threat than other thrips species. Nonetheless, the present research provides a clearer understanding of the thrips species composition, offering essential insights for effective management. Five thrips species from four genera were identified. Retithrips syriacus was previously recorded on roses in Sri Lanka (Tillekaratne et al. 2011 ), while T. parvispinus has been documented in Indonesia and Europe (EPPO 2022; Johari et al . 2022). According to EPPO (2022), Rosa sp. is a known host of T. palmi . However, a review of scientific literature indicates that these three species have not yet been reported on roses in India. The western flower thrips, F. occidentalis , was first recorded in India in 2015 (Tyagi and Kumar 2015 ). This species is a highly viruliferous vector of Orthotospoviruses and also inflicts direct damage to plants through feeding (Rugman-Jones et al. 2010 ). Over the past two decades, it has spread globally and is known for its extreme polyphagy (He et al. 2020 ). However, since its initial report, occurrences in India have been limited, with no significant economic impact on crops observed so far (Suganthy et al. 2016 ; Rachana and Varatharajan 2018 ; Singha et al. 2019 ). Frankliniella occidentalis was previously recorded on roses under protected cultivation in Srinagar in the union territory of Jammu and Kashmir (Suman et al. 2024 ). The species may be actively breeding on roses, and if the host functions as a reservoir, the likelihood of this pest spreading to other parts of India via cut flowers is significantly high. Additionally, the trade of cut flowers could inadvertently facilitate the dispersal of F. occidentalis to different regions across the country. In India, the invasion of T. parvispinus has triggered a lag phase (Rachana et al. 2022 ) following its initial report. Consequently, its population has surged at an alarming rate over just four years, causing significant economic losses for the country's chilli growers (Verma et al. 2022 ). Similar lag phases have been observed in the invasions of other exotic species (Crooks and Soule 1999; Crooks 2005 ; Kelly et al. 2021 ). Given this pattern, the possibility that F. occidentalis is currently undergoing a lag phase cannot be dismissed, raising concerns of a sudden, unexpected outbreak in the future. Under these circumstances, it is imperative for the country to implement a robust quarantine system to prevent the further spread of this destructive pest across India. The presence of T. parvispinus warrants careful evaluation, as it poses a significant risk of spreading and causing economic damage to rose cultivation. Being a highly polyphagous species, if left unmanaged, it could extend to other susceptible crops, with the rose crop serving as a perennial reservoir for its population. The occurrence of F. occidentalis and T. parvispinus among the thrips species infesting roses suggests that these pests could become persistent threats in the future, leading to serious consequences for rose growers. Our study highlights the need to view thrips infestation in rose as a species complex rather than attributing it to a single species in most cases. Further, in India, roses are also cultivated under protected conditions, which can allow thrips species to infiltrate and establish themselves within these environments. A similar pattern was observed in southern France, where thrips diversity was greater outside greenhouses, and their migration into protected spaces led to establishment and further population growth inside (Pizzol et al., 2014 ). Consequently, managing thrips with chemical insecticides will be challenging because these treatments are most effective against immature thrips, which typically feed deep inside buds or flowers — areas that pesticides often fail to penetrate. The present study did not reveal any consistent correlation between specific thrips species and distinct symptom expressions, underscoring the critical need for direct collection and taxonomic identification of thrips rather than relying solely on symptomatology for implementing effective control measures. The detailed photomicrographs provided here, showcasing the diagnostic characteristics of five thrips species, will serve as a valuable resource for students and researchers in accurately identifying these pests. Declarations Acknowledgments We express our sincere gratitude to all the farmers who generously permitted sampling in their rose crops. We also extend our appreciation to Mr S. Pandian for his valuable assistance in the collection and rearing of thrips species. This research was supported through an institute-funded project awarded to P.S.K. References Amutha M, Rachana RR (2023) Species diversity of thrips on cotton. Indian J Entomol 85(1):78–82 Armstrong KF, Ball SL (2005) DNA barcodes for biosecurity: invasive species identification. Philos Trans R Soc Lond Ser B 360(1462):1813–1823. https://doi.org/10.1098/rstb.2005.1713 Bertaux F, Poncet C, Pionnat JC (2003) Les maladies et parasites. In: Brun R, Mary L (eds) [eds.], La rose sous serre pour la fleur coupee. INRA-ASTREDHOR, Paris, France, pp 145–163. In Crooks JA (2005) Lag times and exotic species: the ecology and management of biological invasions in slow-motion. Ecoscience 12(3):316–329 Crooks JA, Soulé M (1999) Lag times in population explosions of invasive species: causes and implications. In Invasive Species and Biodiversity Management. Population and Community Biology Series. 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Directorate of Plant Protection Quarantine & Storage Welfare, Faridabad, p 7 Wilson TH (1975) A monograph of the subfamily Panchaetothripinae (Thysanoptera: Thripidae). Mem Amer Ent Inst 23:1–354 Additional Declarations The authors declare no competing interests. Cite Share Download PDF Status: Posted Version 1 posted 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-7928863","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":533751825,"identity":"e0b86073-7383-4d18-9abc-ee58e68ecf8e","order_by":0,"name":"Prakya Sreerama Kumar","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Prakya","middleName":"Sreerama","lastName":"Kumar","suffix":""},{"id":533751826,"identity":"7117f271-70aa-4508-a681-bb0085b8eb62","order_by":1,"name":"Rajan Remani 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07:09:59","extension":"html","order_by":26,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":85529,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7928863/v1/9fb38cfd135f8402aa4ccd83.html"},{"id":94252980,"identity":"948d525e-27ce-4f4a-b8c1-5bd535a8ecf2","added_by":"auto","created_at":"2025-10-24 07:09:58","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":2678550,"visible":true,"origin":"","legend":"\u003cp\u003eYoung rose (cv. ‘Taj Mahal Red’) flushes infested by \u003cem\u003eScirtothrips dorsalis\u003c/em\u003eexhibiting scarring, yellow blotches and upward curling of leaves (A) in a polyhouse at Handenahalli in Anekal taluk of Bengaluru Urban district, Karnataka, India; close-up of the symptoms (B).\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-7928863/v1/4919ab40737ad4f9ddce9a3a.png"},{"id":94252987,"identity":"59f7f6d6-1cb1-49b0-a3d7-e82331a66a7f","added_by":"auto","created_at":"2025-10-24 07:09:59","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":2780636,"visible":true,"origin":"","legend":"\u003cp\u003eRose (cv. ‘Avalanche White’) leaves infested by \u003cem\u003eScirtothrips dorsalis\u003c/em\u003e exhibiting scarring and yellow blotches (A) in a polyhouse at Handenahalli in Anekal taluk of Bengaluru Urban district, Karnataka, India; leaf puckering (B); malformed leaves and bud (C).\u003c/p\u003e","description":"","filename":"image2.png","url":"https://assets-eu.researchsquare.com/files/rs-7928863/v1/edf99a1df550144bee37b7a5.png"},{"id":94253333,"identity":"fa4d5ec4-c0d3-4568-b5b8-1c879f1cbd2e","added_by":"auto","created_at":"2025-10-24 07:17:59","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":4415433,"visible":true,"origin":"","legend":"\u003cp\u003eDeveloping flower bud of rose (cv. ‘Avalanche White’) enclosed in a flower-bud net damaged (arrowed) by \u003cem\u003eScirtothrips dorsalis\u003c/em\u003e in a polyhouse at Handenahalli in Anekal taluk of Bengaluru Urban district, Karnataka, India; thrips activity on a petal caused brown streaks and patches (arrowed) (B).\u003c/p\u003e","description":"","filename":"image3.png","url":"https://assets-eu.researchsquare.com/files/rs-7928863/v1/f4ade6b3e08f4752a6811572.png"},{"id":94253332,"identity":"ea9070af-2757-4655-85d4-457a8982c798","added_by":"auto","created_at":"2025-10-24 07:17:58","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":2531843,"visible":true,"origin":"","legend":"\u003cp\u003eApparently healthy rose (cv. ‘Taj Mahal Red’) flower and an almost developed flower bud within a net (A) in a polyhouse at Handenahalli in Anekal taluk of Bengaluru Urban district, Karnataka, India; adult \u003cem\u003eScirtothrips dorsalis\u003c/em\u003e (arrowed) on an inner petal (B).\u003c/p\u003e","description":"","filename":"image4.png","url":"https://assets-eu.researchsquare.com/files/rs-7928863/v1/1bae934f87da7d51e64b3630.png"},{"id":94253334,"identity":"e575c465-545e-44e1-9f84-db780e07fb16","added_by":"auto","created_at":"2025-10-24 07:17:59","extension":"jpeg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":5824549,"visible":true,"origin":"","legend":"\u003cp\u003eRose (cv. ‘Mirabel’) bud sepals exhibiting scabby brown scars due to thrips infestation in an open field at Kempudommasandra in Anekal taluk of Bengaluru Urban district, Karnataka, India. Also seen are light streaks and dicolouration on blossoms.\u003c/p\u003e","description":"","filename":"image5.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7928863/v1/f2912216baaa4687ae9ea30e.jpeg"},{"id":94252985,"identity":"e7ab10f2-1f74-48dd-ac57-b50a483d9ea2","added_by":"auto","created_at":"2025-10-24 07:09:58","extension":"jpeg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":1209738,"visible":true,"origin":"","legend":"\u003cp\u003eRose (cv. ‘Mirabel’) blossoms severely damaged by thrips in an open field at Kempudommasandra in Anekal taluk of Bengaluru Urban district, Karnataka, India.\u003c/p\u003e","description":"","filename":"image6.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7928863/v1/aa1e75741e728b373a983bc9.jpeg"},{"id":94253034,"identity":"a4ce89e6-5970-4092-91c3-6ea77c81e648","added_by":"auto","created_at":"2025-10-24 07:10:01","extension":"jpeg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":1331675,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eFrankliniella occidentalis\u003c/em\u003e. Female (A); Male (B); Antenna (C); Metanotum (D); Female abdominal tergites IX–X (E); Head (F); Pronotum (G); Male abdominal tergite IX (H); Female abdominal tergite VIII (I); Forewing (J).\u003c/p\u003e","description":"","filename":"image7.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7928863/v1/b70ab3627c20f4704499bb92.jpeg"},{"id":94253335,"identity":"dfb61492-ae6b-4265-8bb9-5dd9f2c7f01a","added_by":"auto","created_at":"2025-10-24 07:17:59","extension":"jpeg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":1842381,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eRetithrips syriacus\u003c/em\u003e. Female (A); Head and prothorax (B); Antenna (C); Abdominal tergites (D); Pteronota (E); Pterosterna (F); Forewing (G).\u003c/p\u003e","description":"","filename":"image8.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7928863/v1/098b169bd46dd39f048cfa7e.jpeg"},{"id":94253340,"identity":"3b4724b5-f0ec-4d15-9c41-337953188042","added_by":"auto","created_at":"2025-10-24 07:17:59","extension":"jpeg","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":853156,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eScirtothrips dorsalis\u003c/em\u003e. Female (A); Head (B); Metanotum (C); Pronotum (D); Antenna (E); Forewing (F).\u003c/p\u003e","description":"","filename":"image9.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7928863/v1/6e3b7ce95076ed6b941d6dd4.jpeg"},{"id":94253008,"identity":"9f20e333-022f-496c-9c16-3895ed39451a","added_by":"auto","created_at":"2025-10-24 07:09:59","extension":"jpeg","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":1141181,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eThrips palmi\u003c/em\u003e. Female (A); Antenna (B); Pteronota (C); Forewing (D); Pronotum (E); Head (F); Abdominal tergite VIII (G).\u003c/p\u003e","description":"","filename":"image10.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7928863/v1/39ab785319e7d029cb6618e7.jpeg"},{"id":94252982,"identity":"d6cef24b-cbeb-4d25-aa45-e83d6a350cc9","added_by":"auto","created_at":"2025-10-24 07:09:58","extension":"jpeg","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":900119,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eThrips parvispinus\u003c/em\u003e. Female (A); Antenna (B); Pronotum (C); Head (D); Metanotum (E); Abdominal tergite VIII (F); Forewing (G).\u003c/p\u003e","description":"","filename":"image11.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7928863/v1/b793384050532e80074b5b76.jpeg"},{"id":94254092,"identity":"4cde6c7f-77af-4ccd-8ce5-cb9572e09238","added_by":"auto","created_at":"2025-10-24 07:26:17","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":31697118,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7928863/v1/feee016d-eb32-4a9e-a346-7d52e16c002b.pdf"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003e\u003cstrong\u003eWidening range of thrips in open-field rose cultivation: three species newly identified as pests in southern India\u003c/strong\u003e\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eIn India, roses (\u003cem\u003eRosa\u003c/em\u003e spp.) are cultivated both in open fields and under protected environments such as greenhouses and polyhouses, with a number of insects, mites and diseases emerging as significant constraints in both settings. Thrips (Thysanoptera) in particular are major pests, causing economic losses ranging from 28 to 95 per cent (Gahukar \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2003\u003c/span\u003e), in addition to aesthetic deterioration. With their asymmetrical rasping-sucking mouthparts, thrips pierce plant tissue and extract liquid food, thus inflicting various forms of damage, including silvering and upward curling of leaves; browning and premature wilting of petals; as well as scarring, bronzing and deformation of flowers and flower buds (Duraimurugan and Jagadish \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Rachana et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eAdult thrips feed on flower petals, causing silvery-white or brown streaks, which ultimately lead to the loss of flower colour (Rachana et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2018\u003c/span\u003e) and thus the ornamental value of roses. Thrips undergo multiple generations per year and tend to aggregate in concealed areas, making insecticide-based management challenging. When present in low numbers, thrips on roses must be detected and managed, as even a few on the flowers can cause petal discoloration (Bertaux et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2003\u003c/span\u003e). Given their rapid life cycle and ability to develop resistance to chemical pesticides, thrips pose a considerable challenge to rose growers.\u003c/p\u003e\u003cp\u003eAlthough comprehensive taxonomic research on thrips species affecting roses in India remains limited, several previous studies have identified the infestation of \u003cem\u003eFrankliniella occidentalis\u003c/em\u003e (Pergande), \u003cem\u003eFrankliniella schultzei\u003c/em\u003e (Trybom), \u003cem\u003eScirtothrips dorsalis\u003c/em\u003e (Hood) and \u003cem\u003eThrips hawaiiensis\u003c/em\u003e (Morgan) (Rachana et al., \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Ranaware et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Suman et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Conversely, the majority of pest management studies have largely hypothesized that \u003cem\u003eS. dorsalis\u003c/em\u003e is the predominant species in Indian rose cultivation.\u003c/p\u003e\u003cp\u003eThrips can disperse through flight, infested planting material or wind currents (Mound \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e1983\u003c/span\u003e), and can successfully establish in new areas if suitable environmental conditions are present (McDonald et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e1998\u003c/span\u003e). Therefore, precise identification of pest species is essential for formulating effective management strategies tailored to the targeted pests.\u003c/p\u003e\u003cp\u003eResearchers can detect subtle variations in pest species composition by systematically monitoring multiple pest species within a crop. This approach is particularly crucial for invasive thrips, which can disperse over extensive distances either through natural mechanisms or inadvertent human activity (Morse and Hoddle \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2006\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eReports of two invasive thrips species, \u003cem\u003eF. occidentalis\u003c/em\u003e and \u003cem\u003eThrips parvispinus\u003c/em\u003e (Karny) (Tyagi and Kumar \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Tyagi et al. \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2015\u003c/span\u003e), in India require special attention, as both are potential polyphagous plant pests. Additionally, \u003cem\u003eF. occidentalis\u003c/em\u003e is known to act as a vector for Orthotospoviruses (Rachana et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eIn 2021, chilli farmers in Telangana, a southern state of India, mistakenly identified a \u003cem\u003eT. parvispinus\u003c/em\u003e outbreak as a mite infestation. This misdiagnosis led to the use of inappropriate pesticides, causing a thrips flare-up that reduced yields by nearly 80 per cent (Verma et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Thus, incorrect identification of emerging pest populations can have unforeseen consequences, particularly concerning biosafety and management (Armstrong and Ball \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Venette and Hutchison \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe purposes of this article are to inspect and document the thrips species composition infesting rose in southern India, to describe the symptoms of damage, and to illustrate the significant diagnostic characteristics of the species collected on that host.\u003c/p\u003e"},{"header":"Field collection, mounting and identification of thrips specimens","content":"\u003cp\u003eBetween January 2019 and December 2024, more than 400 thrips specimens were collected from various rose cultivars cultivated across the southern Indian states of Andhra Pradesh, Karnataka, and Tamil Nadu. Roses cultivated under protected conditions within polyhousese were also sampled, in addition to those grown in open fields. Sampling focused on leaves exhibiting characteristic tissue responses commonly associated with thrips infestation, such as puckering, crinkling, twisting, curling, streaking, malformation and discolouration, in order to identify the causative thrips species. Similarly, flower buds and fully opened flowers displaying visible symptoms of damage or suspected to contain thrips were also collected. In polyhouses, developing flower buds enclosed in soft, elastic protective sleeves (flower-bud nets) \u0026mdash; used to prevent premature opening, pest damage, mechanical injury and petal ruffling caused by wind or handling \u0026mdash; and exhibiting brown streaks and morphological abnormalities were also collected for assessment.\u003c/p\u003e\u003cp\u003eAdult thrips were observed on leaf surfaces, within leaf axils, inside curled leaves and beneath flower calyxes. They were extracted in the field by gently tapping infested leaves over a white plastic tray. In instances where mixed-species infestation was suspected, rose twigs, flower buds and flowers harbouring thrips immatures and eggs were enclosed in transparent polypropylene bags (Sreerama Kumar et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) and maintained under laboratory conditions until adult emergence. Prior to bagging, all symptomatic plant material was meticulously examined under a stereozoom microscope (Nikon SMZ800) to exclude the presence of other arthropod pests occupying the same ecological niche.\u003c/p\u003e\u003cp\u003eThrips specimens were preserved in vials containing AGA medium (9 parts 10% ethyl alcohol, 1 part glacial acetic acid and 1 ml Triton X-100 per 1,000 ml of the mixture) for further processing. From the preservative medium, specimens were first immersed in 2% NaOH for 30 min, then transferred to 60% ethyl alcohol for 24 h, followed by dehydration through a graded series of 70\u0026ndash;100% ethyl alcohol washes. After clearing in clove oil for 5\u0026ndash;10 min, specimens were individually mounted in Canada balsam on microscope slides and dried at 45\u0026deg;C for 30 min in an oven. The slides were examined using an Olympus BX51 microscope (4\u0026times; and 10\u0026times;), and photomicrographs of taxonomically significant characters were captured with an Olympus DP23 camera attached to the microscope. Final figure compositions were created using Adobe Photoshop CS2 software.\u003c/p\u003e\u003cp\u003eThe specimens were identified to species level using the taxonomic keys provided by Amutha and Rachana (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) and Wilson (\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e1975\u003c/span\u003e). Voucher specimens were deposited in the National Insect Museum at the Indian Council of Agricultural Research \u0026ndash; National Bureau of Agricultural Insect Resources (ICAR\u0026ndash;NBAIR), Bengaluru, India.\u003c/p\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eThrips species composition\u003c/h2\u003e\u003cp\u003eTaxonomic studies identified five species of thrips belonging to the suborder Terebrantia (Thysanoptera): \u003cem\u003eFrankliniella occidentalis\u003c/em\u003e, commonly known as the western flower thrips; \u003cem\u003eRetithrips syriacus\u003c/em\u003e (Mayet), the black vine thrips; \u003cem\u003eScirtothrips dorsalis\u003c/em\u003e, the chilli thrips; \u003cem\u003eThrips palmi\u003c/em\u003e Karny, the melon thrips; and \u003cem\u003eThrips parvispinus\u003c/em\u003e, referred to as the Southeast Asian thrips. While \u003cem\u003eR. syriacus\u003c/em\u003e belongs to the subfamily Panchaetothripinae, the other four are classified under the subfamily Thripinae, all within the family Thripidae. Among the five, \u003cem\u003eS. dorsalis\u003c/em\u003e was the only thrips found infesting roses in the surveyed polyhouses in Bengaluru Urban and Ramanagara districts in Karnataka. It was also found to infest open-field rose in Bengaluru Rural and Kolar districts of the same state. \u003cem\u003eFrankliniella occidentalis, T. palmi\u003c/em\u003e and \u003cem\u003eT. parvispinus\u003c/em\u003e along with \u003cem\u003eS. dorsalis\u003c/em\u003e were found simultaneously infesting rose at Kalahalli in Bengaluru Rural district. \u003cem\u003eRetithrips syriacus\u003c/em\u003e was observed as a pest of rose in Araku Valley of Alluri Sitharama Raju district in Andhra Pradesh.\u003c/p\u003e\u003c/div\u003e"},{"header":"Damage symptoms","content":"\u003cp\u003eWithin polyhouses, \u003cem\u003eS. dorsalis\u003c/em\u003e was observed on rose leaves, leaf axils, beneath calyxes and nestled within petals, inflicting significant damage to both foliage and blooms. The characteristic injuries caused by this species were recognized as typical indicators of thrips infestation. Young flushes infested by thrips exhibited scarring, yellow blotches, brown streaks and upward curling of leaves (Figs. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e \u0026amp; \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e). Feeding during the flower bud initiation stage resulted in visible damage, especially to the outer sepals, leading to malformed buds that either opened incompletely or failed to develop (Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e). Developing flower buds enclosed in flower-bud nets were found to be vulnerable to infestation by \u003cem\u003eS. dorsalis\u003c/em\u003e in polyhouse conditions (Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e). Under open field conditions, thrips activity on petals caused silvery-white or brown streaks, leading to loss of natural coloration, formation of irregular brown patches, and browning along the edges. Rose bud sepals exhibited scabby brown scars (Figs. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e \u0026amp; \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e). However, no distinct symptoms could be consistently linked to any specific thrips species in open-field roses.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDiagnostic key to the reported species\u003c/strong\u003e\u003c/p\u003e\n\u003col\u003e\n \u003cli\u003eForewings with calluses (Fig. 8G); body short and stout (Fig. 8A)\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;...\u0026hellip;...\u003cstrong\u003e\u003cem\u003e\u0026nbsp;syriacus\u003c/em\u003e\u003c/strong\u003e\u003c/li\u003e\n\u003c/ol\u003e\n\u003cul\u003e\n \u003cli\u003eForewings without callosities; body normal\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;..\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;2\u003c/li\u003e\n\u003c/ul\u003e\n\u003col start=\"2\"\u003e\n \u003cli\u003eAntennae 8 segmented (Fig. 7C) ........................................................................................ 3\u003c/li\u003e\n\u003c/ol\u003e\n\u003cul\u003e\n \u003cli\u003eAntennae 7 segmented (Fig. 10B) \u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;....\u003cstrong\u003e4\u003c/strong\u003e\u003c/li\u003e\n\u003c/ul\u003e\n\u003col start=\"3\"\u003e\n \u003cli\u003eAbdominal tergites with closely spaced microtrichial rows laterally; forewing veins with non-uniform setal rows (Fig. 9F)\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;.\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;...\u0026hellip;\u0026hellip;..\u0026hellip;\u003cstrong\u003e\u003cem\u003e\u0026nbsp;dorsalis\u003c/em\u003e\u003c/strong\u003e\u003c/li\u003e\n\u003c/ol\u003e\n\u003cul\u003e\n \u003cli\u003eAbdominal tergites without lateral microtrichial rows; forewing veins with uniform setal rows (Fig. 7J) \u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;..\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u003cstrong\u003e\u003cem\u003e\u0026nbsp;occidentalis\u003c/em\u003e\u003c/strong\u003e\u003c/li\u003e\n\u003c/ul\u003e\n\u003col start=\"4\"\u003e\n \u003cli\u003eMetanotal sculpture striate longitudinally (Fig. 10C); abdominal tergite VIII with complete posteromarginal comb (Fig. 10G); abdominal sternites without discal setae\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;..\u0026hellip;\u0026hellip;\u0026hellip;..........\u003cstrong\u003e\u003cem\u003e\u0026nbsp;palmi\u003c/em\u003e\u003c/strong\u003e\u003c/li\u003e\n\u003c/ol\u003e\n\u003cul\u003e\n \u003cli\u003eMetanotal sculpture reticulate (Fig. 11E); abdominal tergite VIII without complete posteromarginal comb (Fig. 11F); abdominal sternites with discal setae\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;.\u0026hellip;\u0026hellip;\u0026hellip;...\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;..................\u003cstrong\u003e\u003cem\u003e\u0026nbsp;parvispinus\u003c/em\u003e\u003c/strong\u003e\u003c/li\u003e\n\u003c/ul\u003e"},{"header":"Diagnostic characters of the thrips species","content":"\u003cp\u003eDiagnostic characters of \u003cem\u003eF. occidentalis\u003c/em\u003e, \u003cem\u003eR. syriacus\u003c/em\u003e, \u003cem\u003eS. dorsalis\u003c/em\u003e, \u003cem\u003eT. palmi\u003c/em\u003e and \u003cem\u003eT. parvispinus\u003c/em\u003e are depicted in Figs.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e7\u003c/span\u003e, \u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e8\u003c/span\u003e, \u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e9\u003c/span\u003e, \u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e10\u003c/span\u003e and \u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e, and the morphological characters indicated in those figures are adapted from Rachana and Varatharajan \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2018\u003c/span\u003e, Wilson \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e1975\u003c/span\u003e and Sreerama Kumar et al. \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2024\u003c/span\u003e, respectively. These diagnostic characters are as follows;\u003c/p\u003e\u003cp\u003e\u003cb\u003eFrankliniella occidentalis\u003c/b\u003e \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e7\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eDiagnosis.\u003c/b\u003e Body yellow with median brown patches on abdominal tergites; leg; fore wing shaded. Head with ocellar pair III arising between parallel tangent of fore and hind ocelli; six pairs of postocular setae, pair IV distinctively longer than others. Pronotum with four small setae between the major anteromarginal setae. Metanotum reticulate; campaniform sensilla present. Abdominal tergite VIII with irregular comb of microtrichia.\u003c/p\u003e\u003cp\u003e\u003cb\u003eRetithrips syriacus\u003c/b\u003e \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e8\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eDiagnosis.\u003c/b\u003e Body blackish brown, reticulated polygonally, legs brown except yellow tarsi. Antennae 8 segmented. Forewing apical half with 3 calluses between the costal and anterior veins; anterior margin without fringe cilia, posterior fringe cilia straight. Abdominal tergites reticulate; I with constricted posterior submedian areas, II-X with reticulate median depressed area, III-VII each with a submedian pair of toothed comb on posterior margin, VIII with complete posteromarginal comb of long microtrichia.\u003c/p\u003e\u003cp\u003e\u003cb\u003eScirtothrips dorsalis\u003c/b\u003e \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e9\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eDiagnosis.\u003c/b\u003e Body yellow, median brown shades on abdominal tergites III\u0026ndash;VII, dark antecostal ridges on abdominal tergites and sternites. Interocellar setae pair arise between hind ocelli. Median setae pair on metanotum placed well behind anterior margin. Forewing second vein with 2 setae. Lateral tergal microtrichial fields on abdomen with 3 discal setae; tergite VIII with complete posteromarginal comb. Abdominal sternites with microtrichia extending across median area but limited to posterior half.\u003c/p\u003e\u003cp\u003e\u003cb\u003eThrips palmi\u003c/b\u003e \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e10\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eDiagnosis.\u003c/b\u003e Yellow body. Metanotum having longitudinal lines converging posteriorly, with anterior transverse lines; median pair of setae placed well behind anterior margin, with campaniform sensilla. Forewing first vein with 3 distal setae. Abdominal tergite VIII with posteromarginal comb complete. Abdominal sternites without discal setae.\u003c/p\u003e\u003cp\u003e\u003cb\u003eThrips parvispinus\u003c/b\u003e \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eDiagnosis.\u003c/b\u003e Body brown; forewing brown with base pale; legs yellow. Interocellar setae pair placed on anterior margins of ocellar triangle. Metanotum reticulate medially; median setae situated behind anterior margin; campaniform sensilla absent. Forewing first and second veins with regular rows of setae. Posteromarginal comb on abdominal tergite VIII absent, a few microtrichia present laterally. Discal setae absent on abdominal sternites II and VII, III\u0026ndash;VI with about 6\u0026ndash;12 discal setae arranged irregularly.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eMost studies in India have assumed \u003cem\u003eS. dorsalis\u003c/em\u003e to be the sole thrips species affecting roses. With its broad host range and tendency to attack both leaves and flowers, \u003cem\u003eS. dorsalis\u003c/em\u003e might pose a significantly greater threat than other thrips species. Nonetheless, the present research provides a clearer understanding of the thrips species composition, offering essential insights for effective management. Five thrips species from four genera were identified. \u003cem\u003eRetithrips syriacus\u003c/em\u003e was previously recorded on roses in Sri Lanka (Tillekaratne et al. \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2011\u003c/span\u003e), while \u003cem\u003eT. parvispinus\u003c/em\u003e has been documented in Indonesia and Europe (EPPO 2022; Johari \u003cem\u003eet al\u003c/em\u003e. 2022). According to EPPO (2022), \u003cem\u003eRosa\u003c/em\u003e sp. is a known host of \u003cem\u003eT. palmi\u003c/em\u003e. However, a review of scientific literature indicates that these three species have not yet been reported on roses in India.\u003c/p\u003e\u003cp\u003eThe western flower thrips, \u003cem\u003eF. occidentalis\u003c/em\u003e, was first recorded in India in 2015 (Tyagi and Kumar \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). This species is a highly viruliferous vector of Orthotospoviruses and also inflicts direct damage to plants through feeding (Rugman-Jones et al. \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). Over the past two decades, it has spread globally and is known for its extreme polyphagy (He et al. \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). However, since its initial report, occurrences in India have been limited, with no significant economic impact on crops observed so far (Suganthy et al. \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Rachana and Varatharajan \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Singha et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cem\u003eFrankliniella occidentalis\u003c/em\u003e was previously recorded on roses under protected cultivation in Srinagar in the union territory of Jammu and Kashmir (Suman et al. \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). The species may be actively breeding on roses, and if the host functions as a reservoir, the likelihood of this pest spreading to other parts of India via cut flowers is significantly high. Additionally, the trade of cut flowers could inadvertently facilitate the dispersal of \u003cem\u003eF. occidentalis\u003c/em\u003e to different regions across the country.\u003c/p\u003e\u003cp\u003eIn India, the invasion of \u003cem\u003eT. parvispinus\u003c/em\u003e has triggered a lag phase (Rachana et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) following its initial report. Consequently, its population has surged at an alarming rate over just four years, causing significant economic losses for the country's chilli growers (Verma et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Similar lag phases have been observed in the invasions of other exotic species (Crooks and Soule 1999; Crooks \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Kelly et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Given this pattern, the possibility that \u003cem\u003eF. occidentalis\u003c/em\u003e is currently undergoing a lag phase cannot be dismissed, raising concerns of a sudden, unexpected outbreak in the future. Under these circumstances, it is imperative for the country to implement a robust quarantine system to prevent the further spread of this destructive pest across India.\u003c/p\u003e\u003cp\u003eThe presence of \u003cem\u003eT. parvispinus\u003c/em\u003e warrants careful evaluation, as it poses a significant risk of spreading and causing economic damage to rose cultivation. Being a highly polyphagous species, if left unmanaged, it could extend to other susceptible crops, with the rose crop serving as a perennial reservoir for its population. The occurrence of \u003cem\u003eF. occidentalis\u003c/em\u003e and \u003cem\u003eT. parvispinus\u003c/em\u003e among the thrips species infesting roses suggests that these pests could become persistent threats in the future, leading to serious consequences for rose growers. Our study highlights the need to view thrips infestation in rose as a species complex rather than attributing it to a single species in most cases.\u003c/p\u003e\u003cp\u003eFurther, in India, roses are also cultivated under protected conditions, which can allow thrips species to infiltrate and establish themselves within these environments. A similar pattern was observed in southern France, where thrips diversity was greater outside greenhouses, and their migration into protected spaces led to establishment and further population growth inside (Pizzol et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). Consequently, managing thrips with chemical insecticides will be challenging because these treatments are most effective against immature thrips, which typically feed deep inside buds or flowers \u0026mdash; areas that pesticides often fail to penetrate.\u003c/p\u003e\u003cp\u003eThe present study did not reveal any consistent correlation between specific thrips species and distinct symptom expressions, underscoring the critical need for direct collection and taxonomic identification of thrips rather than relying solely on symptomatology for implementing effective control measures. The detailed photomicrographs provided here, showcasing the diagnostic characteristics of five thrips species, will serve as a valuable resource for students and researchers in accurately identifying these pests.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAcknowledgments\u003c/h2\u003e\u003cp\u003eWe express our sincere gratitude to all the farmers who generously permitted sampling in their rose crops. We also extend our appreciation to Mr S. Pandian for his valuable assistance in the collection and rearing of thrips species. This research was supported through an institute-funded project awarded to P.S.K.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAmutha M, Rachana RR (2023) Species diversity of thrips on cotton. Indian J Entomol 85(1):78\u0026ndash;82\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eArmstrong KF, Ball SL (2005) DNA barcodes for biosecurity: invasive species identification. 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Front Insect Sci 1:650520. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3389/finsc.2021.650520\u003c/span\u003e\u003cspan address=\"10.3389/finsc.2021.650520\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eVerma OP, Siddiqui A, Nagaraju DK, Goswami MP, Dubey SC, Rachana RR, Raghavendra KV, Rajashekar P, Vijayalakshmi K (2022) Management strategies for invasive thrips (\u003cem\u003eThrips parvispinus\u003c/em\u003e) in chilli (ad-hoc). Technical Booklet- IPM-01/2022. Directorate of Plant Protection Quarantine \u0026amp; Storage Welfare, Faridabad, p 7\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWilson TH (1975) A monograph of the subfamily Panchaetothripinae (Thysanoptera: Thripidae). Mem Amer Ent Inst 23:1\u0026ndash;354\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"ICAR NBAIR","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Frankliniella occidentalis, invasive thrips, new host, Thrips parvispinus","lastPublishedDoi":"10.21203/rs.3.rs-7928863/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7928863/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eRose is a high-value ornamental crop widely cultivated under both open-field and protected conditions in India. Thrips have emerged as a major pest group, causing significant aesthetic and economic damage. This study investigated the species composition of thrips infesting open-field roses in southern India, along with associated damage symptoms and morphological diagnostics. Five species were identified: \u003cem\u003eFrankliniella occidentalis\u003c/em\u003e, \u003cem\u003eRetithrips syriacus\u003c/em\u003e, \u003cem\u003eScirtothrips dorsalis\u003c/em\u003e, \u003cem\u003eThrips palmi\u003c/em\u003e and \u003cem\u003eThrips parvispinus\u003c/em\u003e. Of these, \u003cem\u003eR. syriacus\u003c/em\u003e, \u003cem\u003eT. palmi\u003c/em\u003e and \u003cem\u003eT. parvispinus\u003c/em\u003e represent newly recorded species on roses in India. The study did not reveal a reliable correlation between specific thrips species and identifiable symptom patterns. The presence of invasive, polyphagous species such as \u003cem\u003eF. occidentalis\u003c/em\u003e and \u003cem\u003eT. parvispinus\u003c/em\u003e poses a threat to other susceptible crops, with roses potentially serving as a reservoir. There remains a significant risk of heightened losses should these species establish themselves in roses cultivated under protected environments such as greenhouses and polyhouses. The findings underscore the importance of continuous monitoring and species-specific integrated pest management strategies to mitigate future economic risks.\u003c/p\u003e","manuscriptTitle":"Widening range of thrips in open-field rose cultivation: three species newly identified as pests in southern India","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-24 07:09:54","doi":"10.21203/rs.3.rs-7928863/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"883df9ca-b19c-4920-a0fa-dd72c1314460","owner":[],"postedDate":"October 24th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-10-24T07:09:54+00:00","versionOfRecord":[],"versionCreatedAt":"2025-10-24 07:09:54","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7928863","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7928863","identity":"rs-7928863","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}