Contribution to the Study of the Antimicrobial Properties of Eucalyptus pauciflora Essential Oil and Evaluation of its Acaricidal Effect on Varroa destructor ofBees

Contribution to the Study of the Antimicrobial Properties of Eucalyptus pauciflora Essential Oil and Evaluation of its Acaricidal Effect on Varroa destructor ofBees | 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 Contribution to the Study of the Antimicrobial Properties of Eucalyptus pauciflora Essential Oil and Evaluation of its Acaricidal Effect on Varroa destructor ofBees Ghania Atmani Merabet, Hichem Hazmoune, Abdelmalik Belkhiri This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3953454/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 The antibacterial, antifungal, and acaricidal properties of Eucalyptus pauciflora (Ep) essential oil (EO) from the Constantine region of northeastern Algeria are investigated in this study. The plant’s dry leaves yielded 0.73%. The GC/MS analysis identified 39 compounds, with 1,8-cineole (54.45%) being the most abundant. The E.pauciflora ’s antibacterial activity was tested using the Muller Hinton agar diffusion method on Escherichia coli (E.coli ), Staphylococcus aureus (S.aureus), Klebsiella pneumoniae (K. pneumonia) and Pseudomonas aeruginosa (P.aeruginosa ) at various oil concentrations with DMSO. The diameters of the inhibition zones ranged from 6 mm to 20 mm. The plant’s antifungal power was tested against the tomato fungus Fusarium oxysporum (F.oxysporum) by incorporating the product into the Potato Dextrose Agar (PDA) agar medium. The action of EpEO at different concentrations on mycelial growth was compared to determine inhibition rates. The rates of inhibition ranged from 39.27–84.48%. The oil’s acaricidal activity was tested on beehives infested with Varroa destructor . The biological “swaddling” or “cover crop” method was used. The oil has a statistically significant effect (p < 0.05). The E.pauciflora EO recorded antimicrobial and acaricidal results, indicating that this plant could be used in integrated pest management against the bacteria and fungus tested and the Varroa destructor mite. Eucalyptus pauciflora chemical composition antibacterial activity Fusarium oxysporum Varroa destructor Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 INTRODUCTION Eucalyptus originated in Australia and is now found almost everywhere on the planet, with over 900 species Brooke and Kleinig ( 2004 ). It has spread throughout the world, including Algeria. Eucalyptus is primarily grown for its wood, paper pulp, and essential oils, which have medicinal and therapeutic properties. It is an important source of essential oils in treating infectious diseases and traditional medicine. Eucalyptus essential oil has numerous benefits, including being a respiratory tract antiseptic, expectorant, and analgesic Duraffourd and Lapraz ( 2000 ), and having anti-inflammatory, antimicrobial, anti-dermatophyte, and anti-parasitic properties (Vratnica et al. 2011 ; Filomeno et al. 2016 ). Varroa destructor is a parasitic mite of adult bees, larvae, and pupae that causes significant economic losses in beekeeping and causes bee population loss in Algeria and around the world (Brodschneider et al.2010; Vanengels Dorp et al.2010). Using conventional phytosanitary products harms soil microflora, microfauna, and beneficial insects such as the honeybee Apis mellifera . The situation is constantly deteriorating, and the search for alternatives to chemical products is becoming increasingly important. Alternative treatments containing EOs of Eucalyptus are effective against mites while remaining safe for bees (Atmani-Merabet et al. 2018 ; Habbi-Cherifi 2014 ). To identify the active compounds responsible for these various biological activities, we tested antibacterial power of E.pauciflora species against E. coli , S.aureus , K.pneumoniae , and P. aeruginosa , its antifungal power against Fusarium oxysporum , and its acaricidal effect against Varroa destructor of bees. MATERIAL AND METHODS Plant material Leaves of E.pauciflora were collected in March 2020 at the Draa Naga Arboretum in the Djebel El Ouahch forest of the Wilaya of Constantine in northeastern Algeria. The arboretum is situated between longitudes [X1: 6° 42’ 5”, X2: 6° 42’ 30”) and latitudes (Y1: 36° 20’ 45”, Y2: 36° 22’ 15”), and the reference specimen of species Ep (Ep006504) has been deposited with the Constantine Forest Conservation Service, which manages the arboretum. The essential oil was extracted from dry leaves (700 g) using Clevenger hydrodistillation for 4 h, then dried over anhydrous sodium sulphate and stored at 4°C in an opaque glass bottle. Yield calculation The yield Rd is determined by the ratio of the weight of essential oil to the weight of dry plant matter used for extraction, multiplied by 100 (Fallehand al.2008). Rd = m 1 / m 0 x 100 (1) Where: m 1 is the mass in grams of the essential oil and m 0 is the mass of the dry plant matter. GC/MS analysis The essential oil extracted from fresh leaves of E.pauciflora was analyzed using a gas chromatograph coupled to a GC/MS mass spectrometer (Agilent System HP-5MS.) as follows: Capillary chromatographic column of 30 m (length), 0.25 mm (diameter), and 25 m (film thickness)], with an apolar stationary phase of 5% phenyl and 95% dimethyl polysiloxane. The column compartment temperature was programmed to rise at a rate of 10°C/min from 50 to 200°C; the GC/MS interface was kept at 230°C, and the ionization source was kept at 150°C; helium was used as the gaseous carrier with a flow rate of 0.5 ml/min; the injection volume was 0.5 µl; and the MS ionization energy was 70ev with a scan band of 45–400 u. By comparing mass spectral (MS) data from the NIST-Wiley-MS library, essential components were tentatively identified and confirmed using the Kovats index on the HP-5MS column. Antimicrobial activity Because of the frequency with which certain species contaminate foods and the pathogenicity of some of them, we chose four bacterial strains ( S. aureus, Escherichia coli, K. pneumoniae,and P. aeruginosa ) and one fungal strain ( Fusarium oxysporum ) from Algeria’s Constantine Biotechnology Research Center (CRBT). Antibacterial activity The disk diffusion method (Rios et al. 2005) was used to test the antibacterial activity of four human pathogenic bacteria. Gram-positive strains include K. pneumoniae , P. aeruginosa , S. aureus , and a Gram-negative strain, E. coli . Bacteria were grown for 18 to 24 h on a Mueller Hinton (MH) plate at 30°C before being inoculated onto nutrient agar. A sterile Pasteur pipette was used to extract 3 to 5 perfectly identical colonies. The Pasteur pipette was then inserted into a 5 ml sterile (MH) medium (which can be replaced with physiological water). The optical density of this suspension was adjusted to 0.13–0.19 at 600 nm, and this inoculum was used to inoculate sterile (liquid Mueller Hinton) agar plates poured into Petri dishes with a swab soaked in the suspension in tight ridges. Various EO concentrations in DMSO (dimethyl sulfoxide) were prepared (5%, 10%, 50%, and 100%), and 6 mm diameter Whatman paper discs were soaked in EO at various concentrations and deposited on the surface of Petri dishes. The procedure was repeated four times for each can and dilution. Each strain was tested on MH agar without extract. The plates were kept at 4°C for 2 h to allow the EO to diffuse, and the diameters of the inhibition zones were measured after 24 h of incubation at 37°C. The results are expressed as mean value ± standard deviation and interpreted using the (Poncé et al. 2003 ) scale, which includes the following categories: non-sensitive (-) : less than 8 mm; sensitive (+) : 8 mm to 14 mm; very sensitive (++) : 15 mm to 19 mm; and extremely sensitive (+++) : more than 20 mm. Antifungalactivity The E.pauciflora ’s antifungal activity against the fungus F.oxysporum was tested using the direct contact method on PDA agar medium. The technique involves adding oil to the still-liquid culture medium (PDA) at various concentrations in DMSO (0.2%, 0.1%, and 0.05%). For each concentration, 5 mm diameter mycelial disks are deposited on the surface of the agar medium in the center of Petri dishes after the culture medium has solidified. The procedure was repeated three times for each concentration, with a control of agar (PDA) without extract. F.oxysporum was incubated for 96 h in an oven set to 37°C. Two methods were used to evaluate antifungal activity of the plant. Mycelial growth After 96 h of incubation, mycelial growth was measured by measuring the diameters corresponding to each concentration without considering the diameter of the disc. This value is always compared to control cultures that were started on the same day and under the same conditions (Benouaer 2016 ). Inhibition rate After 96 h of incubation, mycelial growth was measured by measuring the diameters corresponding to each concentration without considering the diameter of the disc. This value is always compared to control cultures that were started on the same day and under the same conditions (Benouaer 2016 ). I% = C - T / C x 100 Where: I% is the rate of growth inhibition, C is the diameter of the control colony, and T is the diameter of the colony in the experiment. (Abd-Ellatif et al. 2011 ) interpreted the results obtained regarding the inhibition rate of diametral growth of tillers. Notably, 30 to 40% indicates low activity, 50 to 60% indicates moderate activity, 60 to 70% indicates good activity, and > 70% indicates excellent activity. Acaricidal activity Study area The experiment was conducted in an apiary in the commune of Azzaba (36°45’41.1 “N, 7°03’50.3 “E) in Skikda. Langstroth-type bee hives ( Apis mellifera ) infested with Varroa destructor were selected and divided into four batches of three hives each: batches 1 to 3 were treated with (1mL/hive/week) of (EpEO + thymol), EpEO and thymol (v/v) respectively (Labeste 2013 ). Batch 4 is the untreated control batch, in which the V. destructor died naturally after falling. Collection, countingand analysis The biological “swaddling” or “covering” method was used (Labeste2013; Ghomari et al. 2014 ). This method is intended for tracking and counting fallen mites. Each hive has a grid tray on which Vaseline-greased diapers are placed, then removed and carefully examined with a hand lens for dead varroa mites. The 1 mL treatment was applied to a cardboard strip that was 1 mm thick, 4 cm wide, and 20 cm long and was placed on the tray grid (Labeste2013). The study lasted 21 days, with dead varroa counted every two days. The layers were meticulously cleaned and replaced after each count. The treatment was repeated on days 7 and 14, and the results were expressed as mean mortality ± standard deviation. During the experiment, the temperature ranged between 20°C and 22°C. RESULTS AND DISCUSSION Essential oil yield The E.pauciflora essential oil was light yellow and had a fresh, heady aroma. The essential oil yield was 0.73%, which was relatively high when compared to the Brazilian species (0.60%) (Filomeno et al. 2016) and the Tunisian species (0.23%) (Ghazghazi et al. 2021). Indeed, EO content is influenced primarily by environmental and genetic factors (Piccaglia et al. 2001) and extraction methods and conditions (Bagheri et al. 2014). Chemical composition E.pauciflora essential oil’s GC/MS analysis revealed 39 compounds (Table 1) (Figure1). 1,8-cineole (57.45%), β-cymene (5.44%), spathulenol (5.38%), trans verbenol (4.31%), α-pinene (3.11%), α-terpineol (2.84%), and globulol (2.76%) were the main constituents of the oil. The chemical composition of EpEO is consistent with the findings of studies that have revealed the presence of numerous bioactive compounds, including 1,8-cineole, which has been identified as a specific marker for essential oils of this genus globally (Atmani-Merabet et al. 2018; Atmani-Merabet 2018; Filomeno et al. 2016). However, analysis of Brazilian oil (Filomeno et al. 2016) revealed a difference in composition, with 'the major compounds being spathulenol (22.6%), p-cymene (19.4%), and globulol (10.4%), which could translate into different biological and pharmacological properties (Bruneton1999). Table1. Result of GC-Ms analysis of E.pauciflora leaf essential oil Compounds % composition KI α-thujene 0,14 930 α-pinene 3,11 939 β-pinene 0,12 979 β-myrcene 0,35 991 1-phellandrene 0,33 1003 p-cymene 0,14 1025 m-cymene 5,44 1031 1,8-cineole 57,45 1030 δ-terpinene 0,14 1047 Durol 0,14 1124 3-methyl Butylester 0,43 2388 D-fenchylalcool 0,35 1139 α-campholenal 0,12 1126 Trans -verbenol 4,31 1144 Pinocarvone 1,02 1165 Borneole 0,55 1166 4-terpineol 2,84 1177 Trans -p-mentha-1(7),8-dien-2-ol 1,04 1185 α-terpineol 1,92 1189 Myrtenol 0,22 1327 Phellandreneepoxyde 0,16 1190 Cis- piperitol 0,12 1208 Carvéol 0,23 1217 Cis -p-mentha-1(7),8-dien-2-ol 0,74 1235 2-methyl-3-phenyl propanal 0,29 1244 Piperitone 0,14 1259 Phellandral 0,16 1273 Carvacrol 0,35 1317 Camphene 1,98 966 Tetradecene 0,14 1400 2,4-di-ter-butylphenol 0,39 1513 Epiglobulol 0,18 1569 Aromadendrene 0,39 1441 Spathulenol 5,38 1578 Globulol 2,76 1578 Viridiflorol 0,82 1593 Isospathulenol 0,29 1644 Octadecene 0,16 1795 KI: compounds were tentatively identified by comparison with mass spectra data (MS) obtained from NIST-Wiley library and confirmed by comparison with Kovats index on HP-5MS column. (%) composition: percentage of concentrations based on peak area integration Antibacterial activity To estimate the plant’s antibacterial activity, we used the (Poncé et al. 2003) scale, and the values of the zones of inhibition are expressed as the mean of four tests ± standard deviation, with diameters ranging from 6 mm to 20 mm (Table 2, Fig. 2). Table2. Diameters of Eucalyptus pauciflora inhibition zones Bacteria Dilution 5 µl Dilution 10 µl Dilution 50 µl Dilution 100 µl DMSO Diameters (mm) E. coli G - 6 ± 0 (-) 13 ± 1,41 (+) 17,5 ± 0,54 (++) 20 ± 0 (++) 0 ,0 S.aureus G+ 7 ± 1,41 (-) 14,5 ± 0,71 (-) 16,5 ± 0,71 (+) 20 ± 0 (++) 0,0 K.pneumoniae G- 7,5 ± 1,12 (-) 15 ± 0 (++) 17,5 ± 0,54 (++) 20 ± 0 (++) 0,0 P.aeruginosa G- 9 ± 0 (+) 14 ± 0 (++) 16 ± 0 (++) 17 ± 0 (++) 0,0 G+: Gram+, G- : Gram –, (+++): Extremely sensitive, (++): very sensitive, (+): Sensitive, (-): non sensitive Our findings show that the oil’s inhibitory power increases with concentration, which can be attributed to an increase in the bioactive molecules responsible for its antibacterial effect (Kheyar et al. 2014).The findings also show that the EO of the species studied had a higher activity on E. coli,K. pneumoniae and P. aeruginosa than S. aureus . Several studies testing the inhibitory activity of EOs found the same result, confirming that Gram (+) bacteria are less sensitive to EOs than Gram (-) bacteria. The complexity of their cell envelope, which contains a double membrane, is linked to their resistance (Filomeno et al. 2016). Antifungal activity The susceptibility of the fungus ( F.oxysporum ) to the essential oil of E.pauciflora was tested using the direct contact method, and the antifungal activity of the EO was evaluated in vitro using two approaches: Mycelial growth The findings indicate that the mycelial growth of F.oxysporum f. sp. Lycopersici (FOL) decreased as EO concentration increased (Fig.3 and Fig.4). Because the concentration was low and did not significantly inhibit FOL filament divergence, the 0.05% concentration produced the largest diameter of mycelial growth (4.6 mm). The diameter is 2.725 mm for 0.1% and 1.175 mm for 0.2% concentration. After 96 h of incubation, the + control had a diameter of 7.575. Inhibition rate For each concentration, the rate of inhibition of F.oxysporum mycelial growth is I% (0.2%) = 84.48%, I% (0.1%) = 64.02%, and I% (0.05%) = 39.27%. (Abd-Ellatif et al. 2011) interpreted the results based on the inhibition rate of diametral growth of tillers. As a result, we can conclude that the species studied in this study has excellent in vitro antifungal activity against F.oxysporum at concentrations of 0.2% and 0.1% but is weak at 0.05% (Table 3, Fig. 5). Table 3. Antifungal activity of Eucalyptus pauciflora Dilutions 0.2% 0.1% 0.05% Inhibition rate (I %) 84,48% (+++) 64,6% (++) 39,27% (+) (+++): Excellent activity(++) : Good activity (+) : Low activity The findings indicate that the antifungal activity of the EO is proportional to its concentration. The diameter of the FOL decreases as we increase the concentration of EO. Furthermore, these findings suggest that the control’s mycelial growth is significant, with a Diameter that varies depending on the incubation time. Our findings support the findings of (Dahou2017) and (Mehani 2015), who discovered an inverse relationship between essential oil concentration and mycelial growth. Acaricidal activity Figure 6 depicts the results of E.pauciflora ’s acaricide field tests. Compared to the control, all infested hives treated showed a significant decrease in Varroa destructor . The batch treated with EpEO+ thymol was the most effective in eliminating the ectoparasite compared to those treated with thymol (p = 0.04) and EpEO (p = 0.003). However, there was no significant difference between batches treated with thymol and EpEO. Although EpEO had a lower fallen varroa value (15.41 ± 2.74) than thymol (34.37±6.56), the difference was not statistically significant (p=0.06). The high variability detected in the apiary could be one reason for this. Other studies (Atmani-Merabet et al. 2018; Atmani-Merabet et al. 2022; Atmani-Merabet 2018; Labeste 2013; Abu Bakar et al. 2019; Charpentier 2013) have found that essential oils of Eucalyptus species have a significant acaricidal potential against Varroa destructor . While our findings agreed with previous authors, we discovered that the combination (EpEO+ thymol) was more effective than thymol treatment in reducing parasite populations within the apiary. The same outcome was observed in four Algerian species: E.robusta, E.sideroxylon, E.globulus, and E.amygdalina (Atmani-Merabet et al. 2018; Atmani-Merabet et al. 2022; Atmani-Merabet 2018). Traditional thymol-only treatments are currently encountering resistance from V. destructor (Charpentier2013; Bruneau 2015), so the approach proposed in our study is based on a combination (EO+thymol) to overcome this resistance problem. On the one hand, the essential oil’s complex composition and remarkable structural diversity will be a difficult barrier for the parasite to overcome in order for it to develop resistance. On the other hand, because most anti-varroa drugs used in Algeria contain a single active ingredient, essential oils with their complex structure may help reduce varroa resistance. CONCLUSION The E.pauciflora ’s essential oil contains a high concentration of 1,8-cineole and demonstrated a significant toxicity threshold in antibacterial, antifungal, and acaricidal tests. It can therefore be considered a promising antimicrobial agent for the pharmaceutical industry in various pharmaceutical forms. In addition, our results confirmed that the EO + thymol combination was more effective than EO or thymol alone in reducing ectoparasite populations. Finally, the use of E.pauciflora oil as a bio-control method against Varroa destructor may help to combat varroa resistance to current treatments by alternating their use with that of essential oils alone or in combination with other compounds such as thymol and other essential oils. Abbreviations E: eucalyptus, Ep: Eucalyptus pauciflora , EOs : essential oils, EpEO : Eucalyptus pauciflora essential oil, E.coli : Escherichia coli , S.aureus : Staphylococcus aureus, K. pneumonia : Klebsiella pneumonia, P.aeruginosa : Pseudomonas aeruginosa, MH : Muller Hinton, DMSO : dimethyl sulphoxide, PDA : Potato Dextrose Agar, F.oxysporum : Fusarium oxysporum, FOL: F.oxysporum f. sp. Lycopersici, V.destructor: Varroa destructor. Declarations ACKNOWLEDGMENTS We are very grateful to Mr Makadem Hamadi, a private beekeeper, who allowed us to use a part of his apiary for experimental purposes. FUNDING The research was done by personal funding. 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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-3953454","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":273593116,"identity":"a5461af0-f49e-4341-a927-98b720790c52","order_by":0,"name":"Ghania Atmani Merabet","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABB0lEQVRIiWNgGAWjYJACZgYDBh4G9saGAxIVB8AiBx4QpYXn8MEDFmcOAFlALQkEtYCARFrygco2iBYGfFp0+xc//FxQsE2GnyHH4MDNeXfk7MUOPwTaYien24Bdi9mNZ8bSMwxu80g2nDE4OHPbM2Me6TQDoJZkY7MDuLQcMGPmAWoxONhjcFhy2+HEHukEkJYDidtwajn+DazF/jCPweG/c0Ba0j/g13K+B2oLG1vCAckGkJYcQrbwFEuDtEicYT5wQOLYYWOe2zkFBxIM8Pjl/PGNn3n+3Lbnn/+w+YNEzWE59tnpmz98qLCTw6WFQSIBq7ABDuUgwI/LrFEwCkbBKBgFMAAAJnRpq4Fi50wAAAAASUVORK5CYII=","orcid":"","institution":"Université de Constantine 3: Universite de Constantine 3","correspondingAuthor":true,"prefix":"","firstName":"Ghania","middleName":"Atmani","lastName":"Merabet","suffix":""},{"id":273593117,"identity":"2b996939-7b29-4d9f-87f7-577d0de0e010","order_by":1,"name":"Hichem Hazmoune","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Hichem","middleName":"","lastName":"Hazmoune","suffix":""},{"id":273593118,"identity":"6beaa5fb-9320-42b2-b422-0c48fc67ce36","order_by":2,"name":"Abdelmalik Belkhiri","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Abdelmalik","middleName":"","lastName":"Belkhiri","suffix":""}],"badges":[],"createdAt":"2024-02-13 11:56:56","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3953454/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3953454/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":51415032,"identity":"c3c1fca8-dfed-443f-8ed0-9640ef4563f2","added_by":"auto","created_at":"2024-02-21 06:41:30","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":171371,"visible":true,"origin":"","legend":"\u003cp\u003eChromatogram of E. pauciflora leaf essential oil\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-3953454/v1/13178314f7c1bb7049ad2a0d.png"},{"id":51415030,"identity":"08067123-348f-40a7-9f8a-abe4c3f883a6","added_by":"auto","created_at":"2024-02-21 06:41:30","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":26017,"visible":true,"origin":"","legend":"\u003cp\u003eAntibacterial activity of E.pauciflora essential oil\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-3953454/v1/650757f330797f4a5be26c49.png"},{"id":51415031,"identity":"2a7e5a47-9d5b-4ae7-a4aa-9a015d344c47","added_by":"auto","created_at":"2024-02-21 06:41:30","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":124878,"visible":true,"origin":"","legend":"\u003cp\u003eMorphology of FOL mycelial growth after 4 days of incubation\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-3953454/v1/433219eb6114e45635ba05fd.png"},{"id":51415034,"identity":"347f4c2c-efa4-4f44-8197-6428baeedf55","added_by":"auto","created_at":"2024-02-21 06:41:30","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":49669,"visible":true,"origin":"","legend":"\u003cp\u003eDiameters of the F.oxysporum mycelial growth at different concentration\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-3953454/v1/4f6587b60f767f6233485c1f.png"},{"id":51415290,"identity":"728d2ad4-4b63-4dbb-b745-87ea020e8c4b","added_by":"auto","created_at":"2024-02-21 06:49:30","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":132026,"visible":true,"origin":"","legend":"\u003cp\u003eThe effect of E. pauciflora oil on the growth inhibition rate of Fusarium oxysporum\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-3953454/v1/b9d60fecd91e93db65ffbd1d.png"},{"id":51415035,"identity":"3aad4c4d-7f1f-453f-87a6-e0165ddb0cb1","added_by":"auto","created_at":"2024-02-21 06:41:30","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":52090,"visible":true,"origin":"","legend":"\u003cp\u003eAcaricidal effect of EpEO against V.destructor\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-3953454/v1/9b8b59ccb000e025062011e0.png"},{"id":51590330,"identity":"86bcb255-8433-4076-8445-4a7fea7fce62","added_by":"auto","created_at":"2024-02-24 18:05:14","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":837125,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3953454/v1/13bd1c25-0725-4a81-9187-b43f39d32016.pdf"}],"financialInterests":"","formattedTitle":"Contribution to the Study of the Antimicrobial Properties of Eucalyptus pauciflora Essential Oil and Evaluation of its Acaricidal Effect on Varroa destructor ofBees","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eEucalyptus originated in Australia and is now found almost everywhere on the planet, with over 900 species Brooke and Kleinig (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2004\u003c/span\u003e). It has spread throughout the world, including Algeria. Eucalyptus is primarily grown for its wood, paper pulp, and essential oils, which have medicinal and therapeutic properties. It is an important source of essential oils in treating infectious diseases and traditional medicine. Eucalyptus essential oil has numerous benefits, including being a respiratory tract antiseptic, expectorant, and analgesic Duraffourd and Lapraz (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2000\u003c/span\u003e), and having anti-inflammatory, antimicrobial, anti-dermatophyte, and anti-parasitic properties (Vratnica et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Filomeno et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). \u003cem\u003eVarroa destructor\u003c/em\u003e is a parasitic mite of adult bees, larvae, and pupae that causes significant economic losses in beekeeping and causes bee population loss in Algeria and around the world (Brodschneider et al.2010; Vanengels Dorp et al.2010). Using conventional phytosanitary products harms soil microflora, microfauna, and beneficial insects such as the honeybee \u003cem\u003eApis mellifera\u003c/em\u003e. The situation is constantly deteriorating, and the search for alternatives to chemical products is becoming increasingly important. Alternative treatments containing EOs of Eucalyptus are effective against mites while remaining safe for bees (Atmani-Merabet et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Habbi-Cherifi \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). To identify the active compounds responsible for these various biological activities, we tested antibacterial power of \u003cem\u003eE.pauciflora\u003c/em\u003e species against \u003cem\u003eE. coli\u003c/em\u003e, \u003cem\u003eS.aureus\u003c/em\u003e, \u003cem\u003eK.pneumoniae\u003c/em\u003e, and \u003cem\u003eP. aeruginosa\u003c/em\u003e, its antifungal power against \u003cem\u003eFusarium oxysporum\u003c/em\u003e, and its acaricidal effect against \u003cem\u003eVarroa destructor\u003c/em\u003e of bees.\u003c/p\u003e"},{"header":"MATERIAL AND METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003ePlant material\u003c/h2\u003e \u003cp\u003eLeaves of \u003cem\u003eE.pauciflora\u003c/em\u003e were collected in March 2020 at the Draa Naga Arboretum in the Djebel El Ouahch forest of the Wilaya of Constantine in northeastern Algeria. The arboretum is situated between longitudes [X1: 6\u0026deg; 42\u0026rsquo; 5\u0026rdquo;, X2: 6\u0026deg; 42\u0026rsquo; 30\u0026rdquo;) and latitudes (Y1: 36\u0026deg; 20\u0026rsquo; 45\u0026rdquo;, Y2: 36\u0026deg; 22\u0026rsquo; 15\u0026rdquo;), and the reference specimen of species Ep (Ep006504) has been deposited with the Constantine Forest Conservation Service, which manages the arboretum. The essential oil was extracted from dry leaves (700 g) using Clevenger hydrodistillation for 4 h, then dried over anhydrous sodium sulphate and stored at 4\u0026deg;C in an opaque glass bottle.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eYield calculation\u003c/h2\u003e \u003cp\u003eThe yield Rd is determined by the ratio of the weight of essential oil to the weight of dry plant matter used for extraction, multiplied by 100 (Fallehand al.2008).\u003c/p\u003e \u003cp\u003eRd\u0026thinsp;=\u0026thinsp;m\u003csub\u003e1\u003c/sub\u003e / m\u003csub\u003e0\u003c/sub\u003e x 100 (1)\u003c/p\u003e \u003cp\u003eWhere: \u003cb\u003em\u003c/b\u003e\u003csub\u003e\u003cb\u003e1\u003c/b\u003e\u003c/sub\u003e is the mass in grams of the essential oil and \u003cb\u003em\u003c/b\u003e\u003csub\u003e\u003cb\u003e0\u003c/b\u003e\u003c/sub\u003e is the mass of the dry plant matter.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eGC/MS analysis\u003c/h2\u003e \u003cp\u003eThe essential oil extracted from fresh leaves of \u003cem\u003eE.pauciflora\u003c/em\u003e was analyzed using a gas chromatograph coupled to a GC/MS mass spectrometer (Agilent System HP-5MS.) as follows: Capillary chromatographic column of 30 m (length), 0.25 mm (diameter), and 25 m (film thickness)], with an apolar stationary phase of 5% phenyl and 95% dimethyl polysiloxane. The column compartment temperature was programmed to rise at a rate of 10\u0026deg;C/min from 50 to 200\u0026deg;C; the GC/MS interface was kept at 230\u0026deg;C, and the ionization source was kept at 150\u0026deg;C; helium was used as the gaseous carrier with a flow rate of 0.5 ml/min; the injection volume was 0.5 \u0026micro;l; and the MS ionization energy was 70ev with a scan band of 45\u0026ndash;400 u. By comparing mass spectral (MS) data from the NIST-Wiley-MS library, essential components were tentatively identified and confirmed using the Kovats index on the HP-5MS column.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eAntimicrobial activity\u003c/h2\u003e \u003cp\u003eBecause of the frequency with which certain species contaminate foods and the pathogenicity of some of them, we chose four bacterial strains (\u003cem\u003eS. aureus, Escherichia coli, K. pneumoniae,and P. aeruginosa\u003c/em\u003e) and one fungal strain (\u003cem\u003eFusarium oxysporum\u003c/em\u003e) from Algeria\u0026rsquo;s Constantine Biotechnology Research Center (CRBT).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eAntibacterial activity\u003c/h2\u003e \u003cp\u003eThe disk diffusion method (Rios et al. 2005) was used to test the antibacterial activity of four human pathogenic bacteria. Gram-positive strains include \u003cem\u003eK. pneumoniae\u003c/em\u003e, \u003cem\u003eP. aeruginosa\u003c/em\u003e, \u003cem\u003eS. aureus\u003c/em\u003e, and a Gram-negative strain, \u003cem\u003eE. coli\u003c/em\u003e. Bacteria were grown for 18 to 24 h on a Mueller Hinton (MH) plate at 30\u0026deg;C before being inoculated onto nutrient agar. A sterile Pasteur pipette was used to extract 3 to 5 perfectly identical colonies. The Pasteur pipette was then inserted into a 5 ml sterile (MH) medium (which can be replaced with physiological water). The optical density of this suspension was adjusted to 0.13\u0026ndash;0.19 at 600 nm, and this inoculum was used to inoculate sterile (liquid Mueller Hinton) agar plates poured into Petri dishes with a swab soaked in the suspension in tight ridges. Various EO concentrations in DMSO (dimethyl sulfoxide) were prepared (5%, 10%, 50%, and 100%), and 6 mm diameter Whatman paper discs were soaked in EO at various concentrations and deposited on the surface of Petri dishes. The procedure was repeated four times for each can and dilution. Each strain was tested on MH agar without extract. The plates were kept at 4\u0026deg;C for 2 h to allow the EO to diffuse, and the diameters of the inhibition zones were measured after 24 h of incubation at 37\u0026deg;C. The results are expressed as mean value\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation and interpreted using the (Ponc\u0026eacute; et al. \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2003\u003c/span\u003e) scale, which includes the following categories: \u003cb\u003enon-sensitive (-)\u003c/b\u003e: less than 8 mm; \u003cb\u003esensitive (+)\u003c/b\u003e: 8 mm to 14 mm; \u003cb\u003every sensitive (++)\u003c/b\u003e: 15 mm to 19 mm; and \u003cb\u003eextremely sensitive (+++)\u003c/b\u003e: more than 20 mm.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eAntifungalactivity\u003c/h2\u003e \u003cp\u003eThe \u003cem\u003eE.pauciflora\u003c/em\u003e\u0026rsquo;s antifungal activity against the fungus \u003cem\u003eF.oxysporum\u003c/em\u003e was tested using the direct contact method on PDA agar medium. The technique involves adding oil to the still-liquid culture medium (PDA) at various concentrations in DMSO (0.2%, 0.1%, and 0.05%). For each concentration, 5 mm diameter mycelial disks are deposited on the surface of the agar medium in the center of Petri dishes after the culture medium has solidified. The procedure was repeated three times for each concentration, with a control of agar (PDA) without extract. \u003cem\u003eF.oxysporum\u003c/em\u003e was incubated for 96 h in an oven set to 37\u0026deg;C. Two methods were used to evaluate antifungal activity of the plant.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eMycelial growth\u003c/h2\u003e \u003cp\u003eAfter 96 h of incubation, mycelial growth was measured by measuring the diameters corresponding to each concentration without considering the diameter of the disc. This value is always compared to control cultures that were started on the same day and under the same conditions (Benouaer \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2016\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eInhibition rate\u003c/h2\u003e \u003cp\u003eAfter 96 h of incubation, mycelial growth was measured by measuring the diameters corresponding to each concentration without considering the diameter of the disc. This value is always compared\u003c/p\u003e \u003cp\u003eto control cultures that were started on the same day and under the same conditions (Benouaer \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2016\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eI% = C - T / C x 100\u003c/h2\u003e \u003cp\u003eWhere: \u003cb\u003eI%\u003c/b\u003e is the rate of growth inhibition, \u003cb\u003eC\u003c/b\u003e is the diameter of the control colony, and \u003cb\u003eT\u003c/b\u003e is the diameter of the colony in the experiment. (Abd-Ellatif et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2011\u003c/span\u003e) interpreted the results obtained regarding the inhibition rate of diametral growth of tillers. Notably, \u003cb\u003e30 to 40%\u003c/b\u003e indicates low activity, \u003cb\u003e50 to 60%\u003c/b\u003e indicates moderate activity, \u003cb\u003e60 to 70%\u003c/b\u003e indicates good activity, and \u003cb\u003e\u0026gt;\u0026thinsp;70%\u003c/b\u003e indicates excellent activity.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eAcaricidal activity\u003c/h2\u003e \u003cdiv id=\"Sec13\" class=\"Section3\"\u003e \u003ch2\u003eStudy area\u003c/h2\u003e \u003cp\u003eThe experiment was conducted in an apiary in the commune of Azzaba (36\u0026deg;45\u0026rsquo;41.1 \u0026ldquo;N, 7\u0026deg;03\u0026rsquo;50.3 \u0026ldquo;E) in Skikda. Langstroth-type bee hives (\u003cem\u003eApis mellifera\u003c/em\u003e) infested with \u003cem\u003eVarroa destructor\u003c/em\u003e were selected and divided into four batches of three hives each: batches 1 to 3 were treated with (1mL/hive/week) of (EpEO\u0026thinsp;+\u0026thinsp;thymol), EpEO and thymol (v/v) respectively (Labeste \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). Batch 4 is the untreated control batch, in which the \u003cem\u003eV. destructor\u003c/em\u003e died naturally after falling.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eCollection, countingand analysis\u003c/h2\u003e \u003cp\u003eThe biological \u0026ldquo;swaddling\u0026rdquo; or \u0026ldquo;covering\u0026rdquo; method was used (Labeste2013; Ghomari et al. \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). This method is intended for tracking and counting fallen mites. Each hive has a grid tray on which Vaseline-greased diapers are placed, then removed and carefully examined with a hand lens for dead varroa mites. The 1 mL treatment was applied to a cardboard strip that was 1 mm thick, 4 cm wide, and 20 cm long and was placed on the tray grid (Labeste2013). The study lasted 21 days, with dead varroa counted every two days. The layers were meticulously cleaned and replaced after each count. The treatment was repeated on days 7 and 14, and the results were expressed as mean mortality\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation. During the experiment, the temperature ranged between 20\u0026deg;C and 22\u0026deg;C.\u003c/p\u003e \u003c/div\u003e"},{"header":"RESULTS AND DISCUSSION","content":"\u003cp\u003e\u003cstrong\u003eEssential oil yield\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe \u003cem\u003eE.pauciflora\u003c/em\u003e essential oil was light yellow and had a fresh, heady aroma. The essential oil yield was 0.73%, which was relatively high when compared to the Brazilian species (0.60%) (Filomeno et al. 2016) and the Tunisian species (0.23%) (Ghazghazi et al. 2021). Indeed, EO content is influenced primarily by environmental and genetic factors (Piccaglia et al. 2001) and extraction methods and conditions (Bagheri et al. 2014).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eChemical composition\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eE.pauciflora\u003c/em\u003e essential oil\u0026rsquo;s GC/MS analysis revealed 39 compounds (Table 1) (Figure1). 1,8-cineole (57.45%), \u0026beta;-cymene (5.44%), spathulenol (5.38%), trans verbenol (4.31%), \u0026alpha;-pinene (3.11%), \u0026alpha;-terpineol (2.84%), and globulol (2.76%) were the main constituents of the oil. The chemical composition of EpEO is consistent with the findings of studies that have revealed the presence of numerous bioactive compounds, including 1,8-cineole, which has been identified as a specific marker for essential oils of this genus globally (Atmani-Merabet et al. 2018; Atmani-Merabet 2018; Filomeno et al. 2016). However, analysis of Brazilian oil (Filomeno et al. 2016) revealed a difference in composition, with \u0026apos;the major compounds being spathulenol (22.6%), p-cymene (19.4%), and globulol (10.4%), which could translate into different biological and pharmacological properties (Bruneton1999).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable1.\u003c/strong\u003eResult of GC-Ms analysis of \u003cem\u003eE.pauciflora\u003c/em\u003e leaf essential oil\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"345\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\"\u003e\n \u003cp\u003e\u003cstrong\u003eCompounds\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\"\u003e\n \u003cp\u003e\u003cstrong\u003e% \u0026nbsp;composition\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\"\u003e\n \u003cp\u003e\u003cstrong\u003eKI\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u0026nbsp;\u0026alpha;-thujene\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e930\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026alpha;-pinene\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u003cstrong\u003e3,11\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e939\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u0026beta;-pinene\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e979\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u0026beta;-myrcene\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e991\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003e1-phellandrene\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1003\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003ep-cymene\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1025\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u003cstrong\u003em-cymene\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u003cstrong\u003e5,44\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1031\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u003cstrong\u003e1,8-cineole\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u003cstrong\u003e57,45\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1030\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u0026delta;-terpinene\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1047\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003eDurol\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1124\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003e3-methyl Butylester\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e2388\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003eD-fenchylalcool\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1139\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u0026alpha;-campholenal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1126\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eTrans\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e-verbenol\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e4,31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1144\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003ePinocarvone\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e1,02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1165\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003eBorneole\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1166\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u003cstrong\u003e4-terpineol\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u003cstrong\u003e2,84\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1177\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u003cem\u003eTrans\u003c/em\u003e-p-mentha-1(7),8-dien-2-ol\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e1,04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1185\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u0026alpha;-terpineol\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e1,92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1189\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003eMyrtenol\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1327\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003ePhellandreneepoxyde\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1190\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u003cem\u003eCis-\u003c/em\u003epiperitol\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1208\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003eCarv\u0026eacute;ol\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1217\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u003cem\u003eCis\u003c/em\u003e-p-mentha-1(7),8-dien-2-ol\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1235\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003e2-methyl-3-phenyl propanal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1244\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003ePiperitone\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1259\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003ePhellandral\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1273\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003eCarvacrol\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1317\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u003cstrong\u003eCamphene\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u003cstrong\u003e1,98\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e966\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003eTetradecene\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1400\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003e2,4-di-ter-butylphenol\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1513\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003eEpiglobulol\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1569\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003eAromadendrene\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1441\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u003cstrong\u003eSpathulenol\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u003cstrong\u003e5,38\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1578\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u003cstrong\u003eGlobulol\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e\u003cstrong\u003e2,76\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1578\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003eViridiflorol\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,82\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1593\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003eIsospathulenol\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1644\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"49.85507246376812%\" valign=\"bottom\"\u003e\n \u003cp\u003eOctadecene\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"27.536231884057973%\" valign=\"bottom\"\u003e\n \u003cp\u003e0,16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.608695652173914%\" valign=\"bottom\"\u003e\n \u003cp\u003e1795\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eKI:\u003c/strong\u003e compounds were tentatively identified by comparison with mass spectra data (MS) obtained \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; from NIST-Wiley library and confirmed by comparison with Kovats index on HP-5MS column. \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u003cstrong\u003e(%)\u003c/strong\u003e composition: percentage of concentrations based on peak area integration\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAntibacterial activity\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo estimate the plant\u0026rsquo;s antibacterial activity, we used the (Ponc\u0026eacute; et al. 2003) scale, and the values of the zones of inhibition are expressed as the mean of four tests \u0026plusmn; standard deviation, with diameters ranging from 6 mm to 20 mm (Table 2, Fig. 2).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable2.\u0026nbsp;\u003c/strong\u003eDiameters of \u003cem\u003eEucalyptus pauciflora\u003c/em\u003e inhibition zones\u0026nbsp;\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"631\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"16.64025356576862%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eBacteria\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.432646592709983%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;Dilution\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e5 \u0026micro;l\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.48177496038035%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eDilution\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e10 \u0026micro;l\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.492868462757528%\"\u003e\n \u003cp\u003e\u003cstrong\u003eDilution\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e50 \u0026micro;l\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.48177496038035%\"\u003e\n \u003cp\u003e\u003cstrong\u003eDilution\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e100 \u0026micro;l\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.47068145800317%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eDMSO\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"100%\" colspan=\"6\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eDiameters (mm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"16.64025356576862%\"\u003e\n \u003cp\u003e\u003cem\u003e\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n \u003cp\u003e\u003cem\u003eE. coli\u003c/em\u003e\u003c/p\u003e\n \u003cp\u003e\u003cem\u003eG -\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.432646592709983%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e6 \u0026nbsp; \u0026nbsp; \u0026plusmn; \u0026nbsp;0\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;(-)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.48177496038035%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e13 \u0026nbsp;\u0026plusmn; 1,41\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; (+)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.492868462757528%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e17,5 \u0026nbsp; \u0026nbsp; \u0026plusmn; \u0026nbsp;0,54\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;(++)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.48177496038035%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e20 \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026plusmn; \u0026nbsp;0\u003c/p\u003e\n \u003cp\u003e(++)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.47068145800317%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e0 ,0\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"16.64025356576862%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cem\u003eS.aureus\u003c/em\u003e\u003c/p\u003e\n \u003cp\u003e\u003cem\u003eG+\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.432646592709983%\" valign=\"top\"\u003e\n \u003cp\u003e7 \u0026nbsp; \u0026nbsp; \u0026plusmn; \u0026nbsp;1,41\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;(-)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.48177496038035%\" valign=\"top\"\u003e\n \u003cp\u003e14,5 \u0026nbsp; \u0026nbsp; \u0026plusmn; \u0026nbsp;0,71\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;(-)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.492868462757528%\" valign=\"top\"\u003e\n \u003cp\u003e16,5 \u0026nbsp; \u0026nbsp; \u0026plusmn; \u0026nbsp;0,71\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; (+)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.48177496038035%\" valign=\"top\"\u003e\n \u003cp\u003e20 \u0026nbsp; \u0026nbsp; \u0026plusmn; \u0026nbsp;0\u003c/p\u003e\n \u003cp\u003e(++)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.47068145800317%\" valign=\"top\"\u003e\n \u003cp\u003e0,0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"16.64025356576862%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cem\u003eK.pneumoniae\u003c/em\u003e\u003c/p\u003e\n \u003cp\u003eG-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.432646592709983%\" valign=\"top\"\u003e\n \u003cp\u003e7,5 \u0026nbsp; \u0026nbsp; \u0026plusmn; \u0026nbsp;1,12\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;(-)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.48177496038035%\" valign=\"top\"\u003e\n \u003cp\u003e15 \u0026plusmn; \u0026nbsp; \u0026nbsp; \u0026nbsp;0\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; (++)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.492868462757528%\" valign=\"top\"\u003e\n \u003cp\u003e17,5 \u0026nbsp;\u0026plusmn; \u0026nbsp; \u0026nbsp; 0,54 \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; (++)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.48177496038035%\" valign=\"top\"\u003e\n \u003cp\u003e20 \u0026nbsp; \u0026nbsp; \u0026plusmn; \u0026nbsp;0\u003c/p\u003e\n \u003cp\u003e(++)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.47068145800317%\" valign=\"top\"\u003e\n \u003cp\u003e0,0\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"16.64025356576862%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cem\u003eP.aeruginosa\u003c/em\u003e\u003c/p\u003e\n \u003cp\u003eG-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.432646592709983%\" valign=\"top\"\u003e\n \u003cp\u003e9 \u0026nbsp; \u0026nbsp; \u0026plusmn; \u0026nbsp;0\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; (+)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.48177496038035%\" valign=\"top\"\u003e\n \u003cp\u003e14 \u0026nbsp; \u0026nbsp; \u0026plusmn; \u0026nbsp;0\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; (++)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.492868462757528%\" valign=\"top\"\u003e\n \u003cp\u003e16 \u0026nbsp; \u0026nbsp; \u0026plusmn; \u0026nbsp;0\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;(++)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.48177496038035%\" valign=\"top\"\u003e\n \u003cp\u003e17 \u0026nbsp; \u0026nbsp; \u0026plusmn; \u0026nbsp;0\u003c/p\u003e\n \u003cp\u003e(++)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.47068145800317%\" valign=\"top\"\u003e\n \u003cp\u003e0,0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eG+: Gram+, G- : Gram \u0026ndash;, (+++): Extremely sensitive, (++): very sensitive, (+): Sensitive, (-): non sensitive\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eOur findings show that the oil\u0026rsquo;s inhibitory power increases with concentration, which can be attributed to an increase in the bioactive molecules responsible for its antibacterial effect \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;(Kheyar et al. 2014).The findings also show that the EO of the species studied had a higher activity on \u003cem\u003eE. coli,K. pneumoniae\u0026nbsp;\u003c/em\u003eand \u003cem\u003eP. aeruginosa\u003c/em\u003e than \u003cem\u003eS. aureus\u003c/em\u003e. Several studies testing the inhibitory activity of EOs found the same result, confirming that Gram (+) bacteria are less sensitive to EOs than Gram (-) bacteria. The complexity of their cell envelope, which contains a double membrane, is linked to their resistance (Filomeno et al. 2016).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAntifungal activity \u0026nbsp;\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe susceptibility of the fungus (\u003cem\u003eF.oxysporum\u003c/em\u003e) to the essential oil of \u003cem\u003eE.pauciflora\u0026nbsp;\u003c/em\u003ewas tested using the direct contact method, and the antifungal activity of the EO was evaluated in vitro using two approaches:\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMycelial growth\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe findings indicate that the mycelial growth of \u003cem\u003eF.oxysporum\u003c/em\u003e f. sp. Lycopersici (FOL) decreased as EO concentration increased (Fig.3 and Fig.4). Because the concentration was low and did not significantly inhibit FOL filament divergence, the 0.05% concentration produced the largest diameter of mycelial growth (4.6 mm). The diameter is 2.725 mm for 0.1% and 1.175 mm for 0.2% concentration. After 96 h of incubation, the + control had a diameter of 7.575.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eInhibition rate \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFor each concentration, the rate of inhibition of \u003cem\u003eF.oxysporum\u003c/em\u003e mycelial growth is\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eI% (0.2%) = 84.48%, I% (0.1%) = 64.02%, and I% (0.05%) = 39.27%. (Abd-Ellatif et al. 2011) interpreted the results based on the inhibition rate of diametral growth of tillers. As a result, we can conclude that the species studied in this study has excellent in vitro antifungal activity against \u003cem\u003eF.oxysporum\u003c/em\u003e at concentrations of 0.2% and 0.1% but is weak at 0.05% (Table 3, Fig. 5).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3.\u003c/strong\u003e\u0026nbsp; \u0026nbsp;Antifungal activity of \u003cem\u003eEucalyptus pauciflora\u003c/em\u003e\u0026nbsp;\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"25%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eDilutions\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\"\u003e\n \u003cp\u003e0.2%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\"\u003e\n \u003cp\u003e0.1%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\"\u003e\n \u003cp\u003e0.05%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25%\"\u003e\n \u003cp\u003e\u003cstrong\u003eInhibition rate\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;(I %)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\"\u003e\n \u003cp\u003e84,48% \u0026nbsp; \u0026nbsp; \u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; (+++)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\"\u003e\n \u003cp\u003e64,6% \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e(++)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\"\u003e\n \u003cp\u003e39,27% \u0026nbsp; \u0026nbsp; \u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;(+)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cstrong\u003e(+++):\u0026nbsp;\u003c/strong\u003eExcellent activity(++)\u0026nbsp;: Good activity\u003cstrong\u003e\u0026nbsp; (+)\u0026nbsp;\u003c/strong\u003e: Low activity\u003c/p\u003e\n\u003cp\u003eThe findings indicate that the antifungal activity of the EO is proportional to its concentration. The diameter of the FOL decreases as we increase the concentration of EO. Furthermore, these findings suggest that the control\u0026rsquo;s mycelial growth is significant, with a Diameter that varies depending on the incubation time. Our findings support the findings of (Dahou2017) and (Mehani 2015), who discovered an inverse relationship between essential oil concentration and mycelial growth.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcaricidal activity\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFigure 6 depicts the results of \u003cem\u003eE.pauciflora\u003c/em\u003e\u0026rsquo;s acaricide field tests. Compared to the control, all infested hives treated showed a significant decrease in \u003cem\u003eVarroa destructor\u003c/em\u003e. The batch treated with EpEO+ thymol was the most effective in eliminating the ectoparasite compared to those treated with thymol (p = 0.04) and EpEO (p = 0.003). However, there was no significant difference between batches treated with thymol and EpEO. Although EpEO had a lower fallen varroa value (15.41 \u0026plusmn; 2.74) than thymol (34.37\u0026plusmn;6.56), the difference was not statistically significant (p=0.06). The high variability detected in the apiary could be one reason for this. Other studies (Atmani-Merabet et al. 2018; Atmani-Merabet et al. 2022; Atmani-Merabet 2018; Labeste 2013; Abu Bakar et al. 2019; Charpentier 2013) have found that essential oils of Eucalyptus species have a significant acaricidal potential against \u003cem\u003eVarroa destructor\u003c/em\u003e.\u003c/p\u003e\n\u003cp\u003eWhile our findings agreed with previous authors, we discovered that the combination \u0026nbsp;(EpEO+ thymol) was more effective than thymol treatment in reducing parasite populations within the apiary. The same outcome was observed in four Algerian species: \u003cem\u003eE.robusta, E.sideroxylon, E.globulus, and E.amygdalina\u0026nbsp;\u003c/em\u003e(Atmani-Merabet et al. 2018; Atmani-Merabet et al. 2022; Atmani-Merabet 2018). Traditional thymol-only treatments are currently encountering resistance from \u003cem\u003eV. destructor\u0026nbsp;\u003c/em\u003e(Charpentier2013; Bruneau 2015), so the approach proposed in our study is based on a combination (EO+thymol) to overcome this resistance problem. On the one hand, the essential oil\u0026rsquo;s complex composition and remarkable structural diversity will be a difficult barrier for the parasite to overcome in order for it to develop resistance. On the other hand, because most anti-varroa drugs used in Algeria contain a single active ingredient, essential oils with their complex structure may help reduce varroa resistance.\u003c/p\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eThe \u003cem\u003eE.pauciflora\u003c/em\u003e\u0026rsquo;s essential oil contains a high concentration of 1,8-cineole and demonstrated a significant toxicity threshold in antibacterial, antifungal, and acaricidal tests. It can therefore be considered a promising antimicrobial agent for the pharmaceutical industry in various pharmaceutical forms. In addition, our results confirmed that the EO\u0026thinsp;+\u0026thinsp;thymol combination was more effective than EO or thymol alone in reducing ectoparasite populations. Finally, the use of \u003cem\u003eE.pauciflora\u003c/em\u003e oil as a bio-control method against \u003cem\u003eVarroa destructor\u003c/em\u003e may help to combat varroa resistance to current treatments by alternating their use with that of essential oils alone or in combination with other compounds such as thymol and other essential oils.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003e\u003cstrong\u003eE:\u003c/strong\u003eeucalyptus, \u003cstrong\u003eEp:\u0026nbsp;\u003c/strong\u003e\u003cem\u003eEucalyptus pauciflora\u003c/em\u003e, \u003cstrong\u003eEOs\u003c/strong\u003e: essential oils, \u003cstrong\u003eEpEO\u003c/strong\u003e: \u003cem\u003eEucalyptus pauciflora\u003c/em\u003e essential oil, \u003cstrong\u003e\u003cem\u003eE.coli\u003c/em\u003e:\u0026nbsp;\u003c/strong\u003e\u003cem\u003eEscherichia coli\u003c/em\u003e, \u003cstrong\u003e\u003cem\u003eS.aureus\u003c/em\u003e\u003c/strong\u003e\u003cem\u003e: Staphylococcus aureus, \u003cstrong\u003eK. pneumonia\u003c/strong\u003e: Klebsiella pneumonia, \u003cstrong\u003eP.aeruginosa\u003c/strong\u003e: Pseudomonas aeruginosa,\u0026nbsp;\u003c/em\u003e\u003cstrong\u003eMH\u003c/strong\u003e: Muller Hinton, \u003cstrong\u003eDMSO\u003c/strong\u003e: dimethyl sulphoxide, \u003cstrong\u003ePDA\u003c/strong\u003e: Potato Dextrose Agar, \u003cstrong\u003e\u003cem\u003eF.oxysporum\u003c/em\u003e:\u0026nbsp;\u003c/strong\u003e\u003cem\u003eFusarium oxysporum,\u0026nbsp;\u003c/em\u003e\u003cstrong\u003eFOL:\u0026nbsp;\u003c/strong\u003e\u003cem\u003eF.oxysporum\u003c/em\u003e f. sp. Lycopersici, \u003cstrong\u003e\u003cem\u003eV.destructor:\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u003cem\u003eVarroa destructor.\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eACKNOWLEDGMENTS\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe are very grateful to Mr Makadem Hamadi, a private beekeeper, who allowed us to use a part of his apiary for experimental purposes.\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFUNDING\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe research was done by personal funding.\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCOMPLIANCE WITH ETHICAL STANDARDS\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis article does not contain any studies with human participants performed by any of the authors.\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCONFLICT OF INTEREST\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no conflicts of interest.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eAbu Bakar M, Anjum Aqueel M, Arshad M, Muhammad Raza MB, Sohail M, Ullah MI (2019) Evaluation of Few Essential Oils for the Management of Parasitic Bee Mites, \u003cem\u003eVarroa destructor\u003c/em\u003e (Acari: Varroidae) in \u003cem\u003eApis mellifera\u003c/em\u003e L. 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Food Chem, 49:239.\u003c/li\u003e\n \u003cli\u003ePonc\u0026eacute; AG, Delvalle C, Fritz R., Roura SI (2003) Anti microbial activity of essential oils on the native microflora of organic Swiss chard. Lebensmitel Wissenschaft and Technologic 36:679-684.\u003c/li\u003e\n \u003cli\u003eRios JL, Recio MC (2005) Medicinal plants and antimicrobial activity. J Ethnopharmacol100:80-4.\u003c/li\u003e\n \u003cli\u003eVanengels Dorp D, Carou D,Hayes Jr, Pettis J.A, Underwood R.M (2010) Survey of managed honey bee colony loses in the USA fall to 2009 to winter. Journal of Apicultural Research50:1-10.\u003c/li\u003e\n \u003cli\u003eVratnica BD, Damjanovic J, Dakov T, Sukovic D, (2011) Antimicrobial effect of essential oil isolated from \u003cem\u003eEucalyptus globulus\u0026nbsp;\u003c/em\u003eLabill. from Montenegro. Czech J. Food Sci. 29:277-284.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"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":"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":"Eucalyptus pauciflora, chemical composition, antibacterial activity, Fusarium oxysporum, Varroa destructor","lastPublishedDoi":"10.21203/rs.3.rs-3953454/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3953454/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe antibacterial, antifungal, and acaricidal properties of \u003cem\u003eEucalyptus pauciflora\u003c/em\u003e (Ep) essential oil (EO) from the Constantine region of northeastern Algeria are investigated in this study. The plant\u0026rsquo;s dry leaves yielded 0.73%. The GC/MS analysis identified 39 compounds, with 1,8-cineole (54.45%) being the most abundant. The \u003cem\u003eE.pauciflora\u003c/em\u003e\u0026rsquo;s antibacterial activity was tested using the Muller Hinton agar diffusion method on \u003cem\u003eEscherichia coli (E.coli\u003c/em\u003e), \u003cem\u003eStaphylococcus aureus (S.aureus), Klebsiella pneumoniae (K. pneumonia)\u003c/em\u003e and \u003cem\u003ePseudomonas aeruginosa (P.aeruginosa\u003c/em\u003e) at various oil concentrations with DMSO. The diameters of the inhibition zones ranged from 6 mm to 20 mm. The plant\u0026rsquo;s antifungal power was tested against the tomato fungus \u003cem\u003eFusarium oxysporum (F.oxysporum)\u003c/em\u003e by incorporating the product into the Potato Dextrose Agar (PDA) agar medium. The action of EpEO at different concentrations on mycelial growth was compared to determine inhibition rates. The rates of inhibition ranged from 39.27\u0026ndash;84.48%. The oil\u0026rsquo;s acaricidal activity was tested on beehives infested with \u003cem\u003eVarroa destructor\u003c/em\u003e. The biological \u0026ldquo;swaddling\u0026rdquo; or \u0026ldquo;cover crop\u0026rdquo; method was used. The oil has a statistically significant effect (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). The \u003cem\u003eE.pauciflora\u003c/em\u003e EO recorded antimicrobial and acaricidal results, indicating that this plant could be used in integrated pest management against the bacteria and fungus tested and the \u003cem\u003eVarroa destructor\u003c/em\u003e mite.\u003c/p\u003e","manuscriptTitle":"Contribution to the Study of the Antimicrobial Properties of Eucalyptus pauciflora Essential Oil and Evaluation of its Acaricidal Effect on Varroa destructor ofBees","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-02-21 06:41:25","doi":"10.21203/rs.3.rs-3953454/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":"51a5a121-569f-4632-8e17-7055e2dbb7aa","owner":[],"postedDate":"February 21st, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-02-24T17:57:07+00:00","versionOfRecord":[],"versionCreatedAt":"2024-02-21 06:41:25","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3953454","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3953454","identity":"rs-3953454","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}