Oviposition Deterrent Activity Research Articles

Elicitors of plant defenses as a standalone tactic failed to provide sufficient protection to fruits against spotted-wing drosophila

Spotted-wing drosophila, Drosophila suzukii (Matsumura), is a globally important invasive pest of soft-skinned fruits including raspberries, blueberries, and strawberries. Current control measures for this pest primarily rely on calendar-based insecticide sprays; therefore, more sustainable methods are desirable. Adults of D. suzukii use cues derived from fruits and symbiotic microbes to identify optimal sites for feeding, mating, and oviposition. We hypothesized that modifying any of these cues could influence D. suzukii adult behavior, making them less likely to select suitable fruits. One approach involves applying synthetic elicitors of the salicylic acid (SA) and jasmonic acid (JA) plant defense pathways, which are associated with defenses against pathogens and herbivores, respectively, or the use of crop sterilants, employed for microbial control, to reduce D. suzukii attraction, oviposition, and larval performance in fruits. Here, the preference and performance of D. suzukii was investigated in blueberry fruits treated exogenously with four commercial elicitors of plant defenses – three that primarily activate SA-related defenses (Actigard, LifeGard, and Regalia) and one activator of JA-related defenses (Blush) – and the crop sterilant OxiDate. A series of choice and no-choice experiments were conducted in laboratory, semi-field, and field settings that were performed at various time intervals to assess the residual effects of each treatment. Our results showed no consistent repellent, oviposition deterrent, or larval toxicity activity for any of the products tested. As a result, our findings do not provide sufficient support to recommend the use of these elicitors or the crop sterilant as viable standalone options for D. suzukii management.

Assessing the bioefficacy of botanical pesticides derived from ethanolic leaf extract of eight invasive plant species against the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae)

ABSTRACT In this study, eight invasive plant species were processed into botanical pesticides, and their bioefficacy was tested against the two-spotted spider mite, Tetranychus urticae. The evaluated botanical pesticides showed high toxicity against adult females of T. urticae, where the mortality ranged from 39.5–99.5% in the treatment groups, while the mortality was 0.5% in the control. Moreover, the oviposition deterrence activity of the botanical pesticides was reflected by the lower number of eggs laid in the treatment groups (9.1–255.5 eggs) compared to the control (504.8 eggs). The ovicidal activity bioassay revealed that the hatchability of eggs following the application of botanical pesticides was reduced to 63.5–95.5%, while the hatchability was 98.8% in the control. However, the ethanolic leaf extract of Mimosa pudica seemed to be the most efficacious botanical pesticide in all parameters observed since it showed high efficacy even when applied at a concentration of 7.5 g/L instead of 10 g/L. Through gas chromatography-mass spectrometry (GC/MS) analysis, 15 phytoconstituents that might be responsible for the anti-mite features were identified. The botanical pesticides used in this study have the potential to be used as environmentally friendly measures to manage T. urticae particularly in organic farming.

Bioactivity and Sublethal Effects of Ageratina adenophora (Asteraceae) on Bactrocera dorsalis (Diptera: Tephritidae)

Abstract Local fruit orchards have incurred heavy losses due to invasive insects, including the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), in Guizhou Province, China. In our efforts to manage this invasive pest, a laboratory study was conducted to evaluate the response of adult B. dorsalis to an extract of Ageratina adenophora (Spreng.) R.M. King & H. Rob (Gunneridae: Asteraceae). We evaluated the contact toxicity and oviposition-deterrent activity of the extract on adult B. dorsalis, as well as the sublethal effects on survival and reproduction. We found that the A. adenophora extract has significant insecticidal activity, with the 24-h median lethal concentration (LC50) for adults being 26.014 mg/ml. The extract of A. adenophora also showed oviposition inhibition. A residual deterrent effect (28.16%) was evident up to 5 d after treatment. Exposure to the LC25 concentration of the A. adenophora extract caused significant differences in preoviposition and fecundity, decreased adult longevity in the F0 generation, and decreased egg and pupa survival in the F1 generation. The levels of carboxylesterase enzyme activity in adults treated with the extract were significantly lower than those in the untreated controls at 12 h and 24 h. This latter phenomenon could perhaps be an adaptive response to the extract that might reduce its toxic effects in B. dorsalis.

Larvicidal and oviposition deterrent activity of sesquiterpenes from the red seaweed Laurencia johnstonii against Aedes aegypti

Larvicidal and oviposition deterrent activity of sesquiterpenes from the red seaweed Laurencia johnstonii against Aedes aegypti

Oviposition Deterrent Activity of Some Wild Plants for Adult Females of Chrysomya albiceps with Medical and Veterinary Importance.

<b>Background and Objective:</b> <i>Chrysomya albiceps</i> is widely spread worldwide, causing myiasis in both humans and animals and playing a mechanical role in the spreading of helminths, viruses and bacteria. Searching for new and safe alternative control methods is very important to eliminate the transmission of pathogens. This study aims to determine the oviposition-deterrent activity of <i>Juniperus procera</i>, <i>Artemisia absinthium</i>, <i>Rosmarinus officinalis</i> and <i>Hypoestes forskaolii</i> wild plants against adult <i>Chrysomya albiceps</i>. <b>Materials and Methods:</b> The effect of plant extracts from <i>Juniperus procera</i>, <i>Artemisia absinthium</i>, <i>Rosmarinus officinalis</i> and <i>Hypoestes forskaolii</i> plants were tested against adult females of <i>Chrysomya albiceps</i> for oviposition deterrent or repellency. These extracts resulted in oviposition deterrent efficacy for adult females of <i>C. albiceps</i> based on the plant type, plant part (leaves or stems), extract type (methanol, acetone and petroleum ether) and tested dose. <b>Results:</b> The highest anti-oviposition activity against <i>C. albiceps</i> females presented from <i>A. absinthium</i> stems acetone extract at a dose of 1 mg cm<sup>2</sup> by 100 %, while at 0.5 mg cm<sup>2</sup> recorded remarkable repellency by 86.7% as compared with the control treatment. According to the dose-response relationship, <i>A. absinthium</i> methanol and acetone extracts were ED<sub>50</sub> values of 0.85, 0.319 mg cm<sup>2</sup> (leaves) and 1.88, 0.576 mg cm<sup>2</sup> (stems), followed by <i>J. procera</i> methanol extract by 0.983 mg cm<sup>2</sup> (leaves) and 0.98 mg cm<sup>2</sup> (stems), respectively achieved highest oviposition deterrent efficiency as compared with other extracts. <b>Conclusion:</b> The high repellency activities of these extracts can be utilized to stop <i>C. albiceps</i> flies from laying eggs on wounds and transmitting myiasis diseases to humans and animals and could potentially replace pesticides used in the future control programs of flies.

Chemical composition of four essential oils and their adulticidal, repellence, and field oviposition deterrence activities against Culex pipiens L. (Diptera: Culicidae)

Effective mosquito repellents can limit the transmission of vector-borne diseases to humans. Consequently, there is an urgent need to develop mosquito control strategies that prioritize eco-friendly and cost-effective repellents. Essential oils (EOs) have enormous potential for mosquito repellency. Here, cinnamon, basil, eucalyptus, and peppermint EOs were investigated for adulticide and repellency properties against Culex pipiens as well on the oviposition behavior of gravid females from laboratory (lab test) and field (field test) populations. Cinnamon oil was an effective oviposition deterrent regardless of the population and had high adulticidal activity with toxicity index of 75.00% at 24 h of exposure, relative to deltamethrin. In addition, it exhibited effective repellency at 98.01% and 71.22% at 6.67 and 1.71 µl/cm2, respectively. Peppermint oil had the least adulticidal activity with toxicity index of 6.2% at 24 h, and it resulted in low repellency at 70.90% and 50.64% at 6.67 and 1.71 µl/cm2, respectively. On average, basil and eucalyptus oils showed some adulticidal efficiency, repellency, and oviposition deterrent activity. For all treatments, the oviposition deterrent index values of gravid females from natural populations (field test) were lower than those from lab-reared (lab test) females. Different ratios of monoterpenoids, phenylpropanoids, and fatty acids in the EOs tested likely account for the activity variations observed. Our results suggest cinnamon, basil, eucalyptus, and peppermint EOs, which are widely available, economical, and eco-friendly, with good potential for mosquito control strategies.

A 2-component blend of coconut oil-derived fatty acids as an oviposition deterrent against Drosophila suzukii (Drosophilidae: Diptera).

Coconut free fatty acid (CFFA), a mixture of 8 fatty acids derived from coconut oil, is an effective repellent and deterrent against a broad array of hematophagous insects. In this study, we evaluated the oviposition deterrent activity of CFFA on spotted-wing drosophila (SWD; Drosophila suzukii), a destructive invasive pest of berries and cherries, and identified bioactive key-deterrent compounds. In laboratory 2-choice tests, CFFA deterred SWD oviposition in a dose-dependent manner with the greatest reduction (99%) observed at a 20-mg dose compared with solvent control. In a field test, raspberries treated with 20-mg CFFA received 64% fewer SWD eggs than raspberries treated with the solvent control. In subsequent laboratory bioassays, 2 of CFFA components, caprylic and capric acids, significantly reduced SWD oviposition by themselves, while 6 other components had no effect. In choice and no-choice assays, we found that a blend of caprylic acid and capric acid, at equivalent concentrations and ratio as in CFFA, was as effective as CFFA, while caprylic acid or capric acid individually were not as effective as the 2-component blend or CFFA at equivalent concentrations, indicating the 2 compounds as the key oviposition deterrent components for SWD. The blend was also as effective as CFFA for other nontarget drosophilid species in the field. Given that CFFA compounds are generally regarded as safe for humans, CFFA and its bioactive components have potential application in sustainably reducing SWD damage in commercial fruit operations, thereby reducing the sole reliance on insecticides.

Insecticidal potential of a Consolida ajacis extract and its major compound (ethyl linoleate) against the diamondback moth, Plutella xylostella

The diamondback moth (Plutella xylostella) is one of the most destructive lepidopteran pests of cruciferous vegetables. However, DBM has developed resistance to current chemical and biological insecticides used for its control, indicating the necessity for finding new insecticides against it. Bio-insecticides derived from plant extracts are eco-friendly alternatives to synthetic pesticides. The aims of this study were to evaluate the insecticidal activity of Consolida ajacis seed extracts against DBM, the underlying mechanism of the control effect of promising extracts, and the identification of the main insecticidal compounds of these extracts. The results showed that ethyl acetate extract of C. ajacis seed exhibited strong contact toxicity (LC50: 5.05 mg/mL), ingestion toxicity, antifeedant, and oviposition deterrent activities against DBM, among the extracts evaluated. At 72 h, glutathiase, acetylcholinesterase, carboxylesterase, peroxidase, and superoxide dismutase activities were inhibited, but catalase activity was activated. The main compound identified from the extract was ethyl linoleate, which had the most significant insecticidal activity on the diamondback moths. This study's findings provide a better understanding of the insecticidal activity of ethyl acetate extract obtained from C. ajacis and its main component (ethyl linoleate). This will help in the development of new insecticides to control DBM.

Coconut oil derived five-component synthetic oviposition deterrent for oriental fruit fly, Bactrocera dorsalis.

Bactrocera dorsalis, oriental fruit fly (OFF), is one of the most destructive agricultural pests. Although bait sprays can effectively control OFF, resistance development has been a concern. We evaluated the oviposition deterrent activity of coconut free fatty acids (CFFA), a mixture of eight coconut oil-derived fatty acids known to repel hematophagous insects and deter their feeding and oviposition, against OFF females. In laboratory 72-h two-choice assays using guava-juice infused-agar as an oviposition substrate, CFFA deterred OFF oviposition in a dose-dependent manner with the greatest reduction of 87% at 20 mg dose compared to the control. When the eight CFFA components were tested individually, four compounds (caprylic, capric, oleic, and linoleic acids) significantly reduced OFF oviposition ('negative-compounds'), two (lauric and myristic acids) had no effect ('neutral-compounds'), and two (palmitic and stearic acids) stimulated OFF oviposition ('positive-compounds'). In two-choice tests, the 'negative-compounds' blend failed to elicit the same level of oviposition reduction as CFFA at equivalent concentrations found in CFFA. Adding the two 'neutral-compounds' recovered the oviposition deterrence similar to CFFA. Subsequent subtraction tests showed that four 'negative-compounds' plus lauric acid was as effective as CFFA in reducing OFF oviposition in guava-juice agar. This five-component key-deterrent blend also reduced OFF oviposition by 95 and 72% on papaya and tomato fruit, respectively. CFFA acts as an oviposition deterrent for OFF. Given that CFFA compounds are generally regarded as safe for humans and the environment, CFFA and its bioactive components have potential use in behavioral control strategies against OFF. © 2023 Society of Chemical Industry. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Oviposition deterrent activity of hydrolate, aqueous extract and major constituents of essential oil from the leaves of Eugenia uniflora (Myrtaceae) for the control of Aedes aegypti

Aedes aegypti is the main vector of arboviral diseases, such as dengue, Zika and chikungunya. The emergence of resistance to synthetic insecticides constitutes an important obstacle to combating the mosquito. Thus, studies have investigated the potential of natural products as an alternative to synthetic chemicals. The aim of the present study was to evaluate the oviposition deterrent activity of different products extracted from the leaves of Eugenia uniflora, which is a native species of Brazil with known bioactive properties but explored little for the control of A. aegypti. The major constituents identified in the essential oil from E. uniflora by gas chromatography coupled to mass spectrometry were selina-1,3,7(11)-trien-8-one (65.83%) and selina-1,3,7(11)-trien-8-one epoxide (13.53%). These major constituents were also identified in the dynamic headspace of the hydrolate and aqueous extract and in the ether fraction of the aqueous extract together with pyrogallol. Other classes of secondary metabolites were also identified in the aqueous extract using high-performance liquid chromatography, such as gallic acid, myricetrin and ellagic acid. The results of the bioassays suggest significant oviposition deterrent activity for the essential oil at concentrations of 9–36 ppm, the isolated substance selina-1,3,7(11)-trien-8-one epoxide at 3.6 ppm, the aqueous extract at 51% (v/v) and hydrolate at 53% (v/v). The magnitude of oviposition deterrent activity for the products extracted from the leaves of E. uniflora, especially the hydrolate and aqueous extract, was one of the most notable ever reported for the inhibition of oviposition by gravid females of A. aegypti. The aqueous extract and hydrolate achieved greater than 90% inhibition. Moreover, the minimum concentration (3.6 ppm) with deterrent activity found for the substance isolated from the essential oil: selina-1,3,7(11)-trien-8-one epoxide - is one of the lowest ever described in the literature.

Mosquitocidal activities of Chenopodium botrys whole plant n-hexane extract against Culex quinquefasciatus.

This research aimed to investigate various mosquitocidal activities of Chenopodium botrys whole- plant n-hexane extract against Culex quinquefasciatus. The extract showed remarkable larvicidal, pupicidal, adulticidal, oviposition deterrent and adult emergence inhibitory activities against Cx. quinquefasciatus. During the larvicidal and pupicidal activities, the 24-hour lethal concentration (LC50) of extract against 2nd instar larvae, 4th instar larvae and pupae were 324.6, 495.6 and 950.8 ppm, respectively. During the CDC (Centers for Disease Control and Prevention) bottle bioassay for adulticidal activity, the median knockdown times (KDT50) at 1.25% concentration was 123.4 minutes. During the filter paper impregnation bioassay for adulticidal activity, the KDT50 value at 0.138 mg/cm2 concentration was 48.6 minutes. The extract was fractionated into 14 fractions through silica gel column chromatography which were then combined into six fractions on the basis of similar retention factor (Rf) value. These fractions were screened for adulticidal activity by applying CDC bottle bioassay. The fraction obtained through 60:40 to 50:50% n-hexanes-chloroform mobile phase with 0.5 Rf value showed 100% adulticidal activity at 0.2% concentration. During oviposition deterrent activity, the highest concentration (1000 ppm) showed 71.3 ± 4.4% effective repellence and 0.6 ± 0.1 oviposition activity index. During adult emergence inhibition activity, the median emergence inhibition (EI50) value was 312.3 ppm. From the outcome of the present investigation, it is concluded that the n-hexane extract of C. botrys whole- plant possesses strong larvicidal, pupicidal, adulticidal, oviposition deterrent and adult emergence inhibitory activities against Cx. quinquefasciatus.

Acaricidal activity of the chinaberry, Melia azedarach L. (Lamiaceae) essential oil against Tetranychus urticae Koch

ABSTRACT The two-spotted spider mite, Tetranychus urticae Koch, is the worst pest for strawberries among all arthropod pests in Iran. In this study, essential oils from the flowering branches and fruits of the chinaberry, Melia azedarach L. were analysed using gas chromatography-mass spectrometry, and the acaricidal activity of the oil was evaluated in fumigation tests against T. urticae. Forty-three constituents were identified and Methanecarbothiolic acid (10.80%), Ethyl Acetate (9.24%), 2-Propanone, 1-fluor (9.01), Acetic acid, 1-methylethyl ester (8.33%) and n-Propyl acetate (8.02%) were the main constituents The mites were susceptible to the oil using the fumigation method. The results stated that M. azedarach oil had high toxicity on eggs and adults of two-spotted spider mite (LC50 was 18.27 and 13.63 µL L−1 for eggs and adults, respectively) with LT50 of 12.05 h. In addition, all tested concentrations had oviposition deterrent activity and repellency on adults of this mite. For the practical use of this oil as a novel acaricide, however, further investigations are needed to evaluate the effects on non-target organisms and the cost-benefit ratio for the formulation of a product to be used on protected crops such as strawberry in the greenhouse condition.

Repellency, contact toxicity, and anti-oviposition effects of three ethanol-extracted plant essential oils on Bemisia tabaci (Hemiptera: Aleyrodidae).

There are more than 1200 species of whiteflies found across the globe. Due to the high level of resistance of whitefly against synthetic insecticides, alternate pest management measures have their significance. Plant essential oils (EOs) affect insect pests in many ways, such as via stimulatory, deterrent, toxic, and hormonal effects. This study was designed to determine the repellency of EOs, toxicity, and oviposition deterrent activities of Allium ascalonicum, Cinnamomum camphora, and Mentha haplocalyx against adult whiteflies. In repellency determination experiments, a single tomato plant was treated with 10ml of ethanol-extracted EO with 1000 ppm concentration. Results showed that C. camphora EO was the most repellent for whitefly compared to M. haplocalyx and A. ascalonicum. The oviposition deterrent experiments revealed that C. camphora has the highest oviposition deterrent effect, followed by M. haplocalyx and A. ascalonicum. A single plant treatment method was used to assess the contact toxicity of three EOs against whitefly after 12, 24, 48, and 72 h of exposure. The results revealed that C. camphora is more toxic to whitefly than M. haplocalyx and A. ascalonicum. After determining the antagonistic effects of these EOs, the oils were analyzed using gas chromatography/mass spectrometry to identify the chemical components. It can be concluded that C. camphora is the most effective oil EO in terms of toxicity, repellence, and oviposition deterrence, followed by M. haplocalyx and A. ascalonicum under greenhouse conditions. Our results introduce some new eco-friendly plant EOs to control whiteflies.

Toxicity of Some Essential Oils Constituents against Oriental Fruit Fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae).

Simple SummaryThe massive use of synthetic pesticides to manage agricultural pests results in environmental pollution and health hazards. The secondary plant metabolites, which are majorly dominated by terpenoids, have the potential to be developed into novel alternatives to synthetic chemicals. Therefore, the present study aimed at evaluating the toxicity, oviposition deterrence, and repellent activities of six majorly dominated essential oil constituents against adults and immature stages of oriental fruit flies, Bactrocera dorsalis. Our results highlight the potential of the selected essential oil constituents to be developed as a novel alternative to synthetic pesticides against B. dorsalis.The massive use of synthetic pesticides to manage agricultural pests results in environmental pollution and health hazards. The secondary plant metabolites, which are majorly dominated by terpenoids, have the potential to be developed into novel alternatives to synthetic chemicals. Therefore, in our current investigation, six majorly dominated essential oil constituents were evaluated for their toxicity against adults and immature stages of oriental fruit flies, Bactrocera dorsalis, a worldwide fruit pest. The results indicated that carvacrol was the most toxic essential oil constituent (EOC) to adult flies, with LC50 of 19.48 mg/mL via fumigant assay, followed by thujone 75% mortality via ingestion toxicity test against adult fruit flies. Similarly, when larvae were dipped in different concentrations of EOCs, carvacrol appeared as the most toxic EOC with the lowest LC50 (29.12 mg/mL), followed by (−)-alpha-pinene (26.54 mg/mL) and (R)-(+)-limonene (29.12 mg/mL). In the oviposition deterrence tests, no egg was observed on oranges seedlings treated with 5% of each EOC (100% repellency). Regarding the repellency assay, a significantly higher number of flies (77%) were repelled from the Y-tube olfactometer arm containing (−)-alpha-pinene, followed by carvacrol (76%). Our results showed that the selected essential oil constituent has the potential to be developed as an alternative to synthetic pesticides against B. dorsalis. However, further research is required to assess the activities of these EOCs under open-field conditions.

Bio-insecticidal and seed protectant effects of four essential oils against Callosobruchus maculatus and Callosobruchus chinensis during storage

In many Integrated Pest Management (IPM) programs, many essential oils were recommended to protect plants from insect’s infestations and have few effects on non-target organisms and the environment. Four essential oils (EOs): Ocimum basilicum, Peganum harmala, Anethum graveolens and Lavandula angustifolia were evaluated against two of the most important stored product insect pests, Callosobruchus maculatuc and C. chinensis infesting cowpea seeds during storage. The tested essential oils were obtained by steam distillation methods of dried plants. Effect of Contact toxicity, insecticidal of lethal concentrations, Oviposition deterrent activity, effect on germination and weight loss of seeds of tested oils were experimented on tested insects. The highest conc. 1% achieved (93, 80 and 77%) in the case of O. basilicum, P. harmala, A. graveolens, respectively in the case of C. maculatus. While in C. chinensis 1% conc. achieved, 90, 72 and 67% in the case of O. basilicum, A. graveolens and P. harmala, respectively. The LC50 of tested oils showed that the LC50 of O. basilicum was significantly decreased 4-fold more than lavender oil and O. basilicum is the best oil against C. maculatus and C. chinensis. Cowpea seeds treated with O. basilicum at high rate (1%) showed maximum prevention in oviposition i.e., 99% followed by A. graveolens causing (63 and 55%) prevention in the oviposition of C. maculatus and C. chinensis, respectively. Least weight loss was observed in O. basilicum and A. graveolens in the case of C. maculatus (4.44±0.47 and 8.13 ± 0.32) and C. chinensis (3.14±0.33 and 6.17 ± 0.12), respectively. O. basilicum treatment achieved the highest Feeding Deterrent Index (FDI) of 92.99 and 89.88% in the case of C. chinensis and C. maculatus, respectively. Least (FDI) was recorded in case of L. angustifolia (36.72 and 32.46%) in the case of C. chinensis and C. maculatus, respectively. Our results confirmed that O. basilicum essential oil had an obvious role in suppressing the activity of the tested insects. O. basilicum essential oil can be used in an integrated pest management program as green pesticide and can be effective alternative for chemical pesticides.

Bio-insecticidal and seed protectant effects of four essential oils against Callosobruchus maculatus and Callosobruchus chinensis during storage

In many Integrated Pest Management (IPM) programs, many essential oils were recommended to protect plants from insect’s infestations and have few effects on non-target organisms and the environment. Four essential oils (EOs): Ocimum basilicum, Peganum harmala, Anethum graveolens and Lavandula angustifolia were evaluated against two of the most important stored product insect pests, Callosobruchus maculatuc and C. chinensis infesting cowpea seeds during storage. The tested essential oils were obtained by steam distillation methods of dried plants. Effect of Contact toxicity, insecticidal of lethal concentrations, Oviposition deterrent activity, effect on germination and weight loss of seeds of tested oils were experimented on tested insects. The highest conc. 1% achieved (93, 80 and 77%) in the case of O. basilicum, P. harmala, A. graveolens, respectively in the case of C. maculatus. While in C. chinensis 1% conc. achieved, 90, 72 and 67% in the case of O. basilicum, A. graveolens and P. harmala, respectively. The LC50 of tested oils showed that the LC50 of O. basilicum was significantly decreased 4-fold more than lavender oil and O. basilicum is the best oil against C. maculatus and C. chinensis. Cowpea seeds treated with O. basilicum at high rate (1%) showed maximum prevention in oviposition i.e., 99% followed by A. graveolens causing (63 and 55%) prevention in the oviposition of C. maculatus and C. chinensis, respectively. Least weight loss was observed in O. basilicum and A. graveolens in the case of C. maculatus (4.44±0.47 and 8.13 ± 0.32) and C. chinensis (3.14±0.33 and 6.17 ± 0.12), respectively. O. basilicum treatment achieved the highest Feeding Deterrent Index (FDI) of 92.99 and 89.88% in the case of C. chinensis and C. maculatus, respectively. Least (FDI) was recorded in case of L. angustifolia (36.72 and 32.46%) in the case of C. chinensis and C. maculatus, respectively. Our results confirmed that O. basilicum essential oil had an obvious role in suppressing the activity of the tested insects. O. basilicum essential oil can be used in an integrated pest management program as green pesticide and can be effective alternative for chemical pesticides.

Oviposition deterrence and repellent activities of selected essential oils against Tuta absoluta Meyrick (Lepidoptera: Gelechiidae): laboratory and greenhouse investigations

Tuta absoluta, an invasive pinworm characterized by high reproductive potential and adaptation to different agroecological conditions, cause serious damage to tomato crops. Chemical control with synthetic insecticides is widely used to control this pest, although pesticides exhibit side effects on non-target organisms and negatively impact the environment, with the occurrence of resistance to some active substances in the target pest. The use of essential oils (EOs) from aromatic or officinal plants could represent an environmentally safe control method, alternative to synthetic insecticide application. In this work we investigated the effect of EOs from Spanish oregano, laurel, basil, garlic, peppermint, cypress, and eucalyptus EOs on T. absoluta oviposition deterrence and larval repellency. Results showed a remarkable oviposition deterrence using laurel, Spanish oregano, basil, and garlic EOs in both laboratory and greenhouse experiments. In no-choice repellence tests carried 1, 2, 6, and 22 h after treatment application, peppermint and Spanish oregano EOs showed the most lasting effects while cypress and eucalyptus EOs were not effective after 6 and 22 h, respectively. In choice tests, at either 5 or 22 h after treatment application, low preference for the test over control by larvae was observed in all treatments, except for basil EO. The most promising effects were observed in Spanish oregano and laurel treatments where no larvae were detected. Repellent effectiveness of EOs does not seem to be influenced when larvae did not get a chance to do a choice between treated and untreated leaves. This study highlights the effectiveness of EOs of aromatic or officinal plants as an alternative to synthetic insecticides for the control of T. absoluta.

Phytochemical and acaricidal study of the Kermani lemongrass, Dracocephalum polychaetum Bornm. (Lamiaceae) essential oil against Tetranychus urticae Koch

ABSTRACT Mites cause significant damage to various crops, often requiring synthetic acaricides for their control. However, the frequent use of these products, resistance problems and severe problems with contamination occur. Therefore, one of the promising solutions is plant acaricides, which can be developed based on essential oils. Thus, the objective of this work was the extraction and characterization of the essential oil from the leaves of Kermani lemongrass, Dracocephalum polychaetum, and acaricidal evaluation of the oil and its major compound using the application by fumigation on female adults of Tetranychus urticae. The composition of the essential oil was analysed by GC-MS. The major components in the oil were 1-octen-3-ol (11.27%), 6-methyl-5-hepten-2-one (11.06%), linalool (9.89), and nonanal (9.64%), respectively. The impact of essential oil of this plant on fumigant toxicity, LT50, oviposition deterrent activity, and repellency against T. urticae was studied at different concentrations. The results stated that D. polychaetum oil had high toxicity on eggs and adults of two-spotted spider mite (LC50 was 60.30 and 50.87 µL L−1 for eggs and adults, respectively) with LT50 of 8.02 h. In addition, all tested concentrations had oviposition deterrent activity and repellency in adults of this mite.

Neem-Based Insecticides Deter Oviposition Activity in Spotted Wing Drosophila (Diptera: Drosophilidae) in Sweet Cherries.

Spotted wing drosophila, Drosophila suzukii (Matsumura), is an important invasive insect pest in the United States. Spotted wing drosophila females have serrated ovipositor that enables them to deposit eggs inside healthy, ripening softskinned fruits. In many berry and fruit crops, spotted wing drosophila is primarily controlled using synthetic insecticides in the organophosphate, pyrethroid, and spinosyn groups. However, alternative, reduced-risk insecticides with short residuals are necessary to minimize the possibilities of insecticide resistance and address other negative effects of synthetic insecticides. Neem-based products as alternative plant-based insecticides have antifeedant, repellent, antiovipository, and molting interference effects on insects and have been shown to affect the oviposition activities of some tephritid flies. We conducted laboratory studies to evaluate the oviposition deterrent activities of selected neem-based insecticides that contain either azadirachtin, or CHENO, or a combination of both, on spotted wing drosophila using sweet cherry in California. The results of the study showed that some of the neem oil products could reduce the degree of spotted wing drosophila oviposition by half compared with the control.

Repellent and oviposition-deterrent efficacies of Cuscuta chinensis on filarial vector Culex quinquefasciatus

In the laboratory, crude and chloroform: methanol extracts of Cuscuta chinensis seeds were evaluated for repellence and oviposition deterrence activities against adults of Culex quinquefasciatus at various concentrations. Hundred percent protection was attained from a 99% concentration of chloroform: methanol extract for 120 minutes whereas from the crude extract for the first 90 minutes with a gradual decrease. Crude and chloroform: methanol extracts of seeds were found to be highly effective in preventing oviposition of adult mosquitoes. Furthermore, neither extract has any negative side effects such as allergy or other observable reactions on human skin during or after the exposure period. Oviposition activity index (OAI) was negative at all concentrations for tested plant extracts which indicated an inhibition of Cx. quinquefasciatus oviposition. So, against Cx. quinquefasciatus mosquito species, crude and chloroform: methanol seed extracts of C. chinensis may be utilized as a repellent and oviposition deterrent.