Oviposition Deterrent Research Articles

Deterrence and behavioral mode of coconut oil-derived free fatty acids on Zeugodacus cucurbitae oviposition.

Previous studies have shown oviposition deterring properties of 8 coconut free fatty acid (CFFA) compounds on fruit flies with different key deterrent components for different species. Here we evaluated oviposition deterrence of CFFA using laboratory 2-choice bioassays against Zeugodacus cucurbitae, determined key-bioactive deterrent compounds, and evaluated their behavioral mode. Unlike other reported fruit fly species, CFFA mixture increased Z. cucurbitae oviposition when directly applied on an oviposition substrate. When tested individually in subsequent tests, 4 compounds (caprylic, capric, oleic, and linoleic acids) significantly reduced the oviposition ("negative-compounds"), 1 compound (stearic acid) had no effect ("neutral-compound"), and 3 compounds (lauric, myristic, and palmitic acids) stimulated the oviposition ("positive-compounds"). The 4-component negative-compound blend was effective at reducing oviposition. However, adding stearic acid to the 4-component blend (5-component blend, 5c) further reduced oviposition. Adding any of the positive-compounds to the 5c resulted in loss of oviposition deterrence, suggesting the 5c as the key deterrent component blend. The blend was also effective in no-choice assays and when applied on cucumbers, a preferred host of Z. cucurbitae. When given a choice, Z. cucurbitae made 48.5% fewer visits, spent 39% less time, and oviposited 88.2% fewer eggs per min on 5c treated pumpkin agar than on control agar, suggesting that the 5c blend has both spatial repellency and contact deterrence. Given that all compounds are registered food additives and generally regarded as safe, this blend has potential application in behavioral control strategies, such as push-pull, to protect host fruit against Z. cucurbitae.

Evaluation of citronella oil nanoemulsion formulation against the insect-stored pest Callosobruchus maculatus (Fab.) (Coleoptera: Bruchidae)

Citronella (Cymbopogon nardus) produces essential oil and has the potential to be developed as a botanical insecticide. However, in its development, botanical insecticides encountered several obstacles. Utilizing nanotechnology in nanoemulsion preparations is one method to overcome these challenges. This research aimed to determine the contents of the citronella oil nanoemulsion (CiONano) and citronella oil non-nano emulsion (CiONonNano) formulations and evaluate the toxicity, repellency, and prevention of oviposition against female adults of Callosobruchus maculatus. This was the first work to evaluate the nanoemulsion of citronella oil prepared from spontaneous emulsification against C. maculatus. Chemical content testing used the GCMS method. A toxicity test using the contact method (LC50), used a probit program, while testing for repellency and oviposition deterrence was carried out using the no-choice method. The highest chemical component of CiONonNano and CiONano was citronella (37.56 and 38.97%, respectively), followed by citronellol (17.71 and 18.99%, consecutively) and geraniol (14.78 and 15.38%, respectively). In general, the CiONano formulation showed higher repellency and toxicity than CiONonNano. The LC50 values of CiONano were 10.03%. These values were 4.49 times lower than the LC50 of CiONonNano. However, the results of the oviposition inhibition test showed different results, the CiONonNano formulation had a higher oviposition inhibition capacity for adult female C. maculatus than CiONano. As a result, it is necessary to optimize the CiONano formulation to obtain consistent results in controlling C. maculatus.

Unravelling the genomic landscape reveals the presence of six novel odorant-binding proteins in whitefly Bemisia tabaci Asia II-1

Genome wide analysis identified 14 OBPs in B. tabaci Asia II-1, of which six are new to science. Phylogenetic analysis traced their diversity and evolutionary lineage among Hemipteran insects. Comparative analysis reclassified the OBP gene families among B. tabaci cryptic species: Asia I, II-1, MEAM1, and MED. The 14 OBPs were clustered on four chromosomes of B. tabaci. RT-qPCR showed high expression of OBP3 and 8 across all body tissues and OBP10 in the abdomen. Molecular docking showed that OBP 3 and 10 had high affinity bonding with different candidate ligands, with binding energies ranging from −5.0 to −7.7 kcal/mol. Competitive fluorescence binding assays revealed that β-caryophyllene and limonene had high binding affinities for OBP3 and 10, with their IC50 values ranging from 9.16 to 14 μmol·L-1 and KD values around 7 to 9 μmol·L-1. Behavioural assays revealed that β-caryophyllene and carvacrol were attractants, β-ocimene and limonene were repellents, and γ-terpinene and β-ocimene were oviposition deterrents to B. tabaci. Functional validation by RNAi demonstrated that OBP3 and OBP10 modulated host recognition of B. tabaci. This study expands our understanding of the genomic landscape of OBPs in B. tabaci, offering scope for developing novel pest control strategies.

Efficacy evaluation of particle films as oviposition deterrent against <i>Drosophila suzukii</i> in Austrian vineyards

Efficacy evaluation of particle films as oviposition deterrent against <i>Drosophila suzukii</i> in Austrian vineyards

Biological control of tephritid fruit flies Bactrocera spp. in Himachal Pradesh, India

Over the years, chemical-based insecticides have been used to enhance crop yield in the agricultural industry. However, the hazards associated with these insecticides have highlighted the need for an alternative method that is economical, eco-friendly, and safe. In this investigation, the efficacy of various biological materials, such as Neem kavach, Beauveria bassiana (Balsamo), and clay, was evaluated against fruit flies under open field conditions. The results revealed that the highest infestation was recorded in the control (71.67 %), while the lowest infestation (25.67 %) was observed in the plot treated with B. bassiana (1.5 %). This was followed by Neem kavach-treated plot (4 %) with an infestation rate of 26.67 %, and the clay-treated plot (15 g/L) with an infestation rate of 38.67 %, after the third spray. The impact of these biological agents on cucumber yield was also evaluated. The highest yield, 9.36 kg/plot, was obtained from the B. bassiana-treated plot, followed by Neem kavach-treated plots with yields of 8.94 and 7.28 kg/plot, respectively. The lowest yield of 4.58 kg/plot was recovered in the untreated plots. These findings suggest that the application of these biological agents is highly effective, as they repel egg-laying (oviposition deterrence), thereby minimizing fruit infestation and maximizing yield profit.

Chemical Composition, Repellent, and Oviposition Deterrent Potential of Wild Plant Essential Oils against Three Mosquito Species.

In this study, the chemical composition, repellent, and oviposition deterrent effects of five plant essential oils (EOs) extracted from Lantana camara (Verbenaceae), Schinus terebinthifolia (Anacardiaceae), Callistemon viminalis (Myrtaceae), Helichrysum odoratissimum (Asteraceae), and Hyptis suaveolens (Lamiaceae) were evaluated against Aedes aegypti, Anopheles gambiae, and Culex quinquefasciatus. When tested at 33.3 µg/cm2, L. camara, S. terebinthifolia, C. viminalis, and H. odoratissimum were effective repellents against Ae. aegypti (89%, 91%, 90%, and 51% repellency, respectively), but they were less repellent against An. gambiae (66%, 86%, 59%, and 49% repellency, respectively). Interestingly, L. camara, S. terebinthifolia, C. viminalis, and H. odoratissimum exhibited 100% repellency against Cx. quinquefasciatus at 33.3 μg/cm2. In time-span bioassays performed at 333 μg/cm2, the EO of L. camara exhibited 100% repellence against Ae. aegypti and An. gambiae for up to 15 min and against Cx. quinquefasciatus for 75 min. The oviposition bioassays revealed that L. camara exhibited the highest activity, showing 85%, 59%, and 89% oviposition deterrence against Ae. aegypti, An. gambiae, and Cx. quinquefasciatus, respectively. The major compounds of L. camara, S. terebinthifolia, and C. viminalis were trans-β-caryophyllene (16.7%), α-pinene (15.5%), and 1,8-cineole (38.1%), respectively. In conclusion, the L. camara and S. terebinthifolia EOs have the potential to be natural mosquito repellents.

Plant growth-promoting rhizobacteria modulate induced corn defense against Spodoptera litura (Lepidoptera: Noctuidae).

Common cutworm, Spodoptera litura is an important pest of corn causing significant crop yield loss. Synthetic insecticides have mostly been used to combat this pest, raising human and environmental health concerns. Plant growth-promoting rhizobacteria (PGPR) could compensate for or augment the harmful effects of agrochemicals. Herein, we aimed to assess whether PGPR-induced defenses in corn plants impact the host-plant selection behavior of S. litura. Headspace volatile organic compounds were analyzed using gas chromatography-mass spectrometry. Larvae fed inoculated corn exhibited lower weights and relative growth rate than noninoculated plants. Under choice experiments, PGPR-treated plants significantly reduced percentage leaf damage area and oviposition rate compared to untreated plants. Volatile organic compound ratio emission varied significantly between control and PGPR treatments, which, in part, explains feeding and oviposition deterrence in PGPR-treated plants. The results demonstrate that PGPR inoculation can enhance corn resistance to S. litura, making it a promising candidate for crop protection strategies.

Effects of natural Ionones and derived novel analogues with simplified structures on behavioral responses of whiteflies.

Whiteflies are major pests in agriculture, causing damage to crops and transmitting plant viruses. Using Volatile Organic Compounds (VOCs) as semiochemicals offers a sustainable approach for combating whiteflies. One such group of compounds, represented by β-ionone, has been found to possess repellent/attractant properties. To further explore the behavioral effects of these compounds on whiteflies, we selected five natural ionone compounds and synthesized six novel analogues to examine the impact of structural variations on whitefly behavior. Our results demonstrated that β-ionone and its analogues have a significant impact on the behavior of whiteflies. Among them, 0.01% pseudo ionone solution exhibited an attractant effect on whiteflies. Notably, the application of 1% β-ionone and 0.1% β-ionol solution demonstrated a notable repellent effect and oviposition deterrent effect on whitefly. We also found that the novel ionone analogue (±)1A exhibited a strong repellent effect. Both β-ionol and compound (±)1A possess high logP values and low saturation vapor pressures, which contribute to enhanced lipophilicity, making them more likely to penetrate insect antennae and prolong their presence in the air. The newly discovered ionone analogue (±)1A and β-ionol exhibit improved repellent effects, while pseudo ionone shows an attractant effect. These three compounds hold promising potential for development as novel biological control agents. Our work highlights the efficacy of VOCs as a protection method against whiteflies. These findings indicate that our new technology for a 'push-pull' control method of B. tabaci can offer a novel tool for integrated pest management (IPM). © 2024 Society of Chemical Industry.

Evaluation of cotton varieties resistant to Amrasca biguttula (Hemiptera: Ciccadelidae) in the Indonesian agroecosystem to mitigate climate change impacts

Climate change employs substantial effects on agroecosystems, particularly the dynamics between plants and herbivores. In response, the adoption of pest-resistant varieties has emerged as a critical strategy within agroecosystems, notably in Indonesia’s cotton Integrated Pest Management (IPM). This research focused on evaluating the response of five cotton lines, which adapted to the Indonesian agroecosystem, to the cotton leafhopper (Amrasca biguttula) as a mitigating measure to climate change. Two upland cotton varieties, Tamcot SP 37 (susceptible) and LRA 5166 (resistant), served as standards for susceptibility and resistance to leafhoppers. The study examined leaf morphological characters, specifically trichome density, known to act as oviposition deterrents for leafhopper females, indicative of non-preference resistance. Low damage scores and high leaf trichome density comparable to the resistant variety (LRA 5166) were indicators of notable field resistance in lines 06062/3/3 and 06062/3/4 against A. biguttula during observations that spanned 35 to 105 days post-planting. These findings highlight the potential of these lines as promising cotton varieties, marked by their resilience to A. biguttula, fostering sustainable cultivation practices that address climate change impacts. This study underscores the intricate dynamics between plant-insect interactions and resilience strategies within agroecosystems.

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.

Effects of Xenorhabdus and Photorhabdus bacterial metabolites on the ovipositional activity of Aedes albopictus

AbstractViral diseases like yellow fever, dengue, and Zika have an alarming impact on public health. These diseases can be transmitted by Aedes mosquito species, such as Ae. albopictus, which is now found in many countries outside its original range. Xenorhabdus and Photorhabdus spp. are enteric bacterial symbionts of insect-preying nematodes and are known to produce an array of natural products with various activities including larvicidal activity. In this study, the effects of natural products produced by four Xenorhabdus and one Photorhabdus bacteria on the ovipositional behavior of Ae. albopictus mosquitoes were assessed. Utilizing a binary choice assay in insect cages, gravid female mosquitoes were presented with two oviposition cups containing water supplemented with varying concentrations of bacterial supernatants (50–1% concentrations) versus control medium. After 72 h, the eggs deposited on filter papers were counted. The oviposition attractant index (OAI) feature of the bacterial supernatant was evaluated using the number of eggs laid in the cups. Notably, all tested supernatants exhibited concentration-dependent deterrence of oviposition. Xenorhabdus cabanillasii displayed the strongest deterrent effect, inhibiting egg-laying at 50–5% concentrations (OAI: − 0.87 to − 0.35), followed by X. nematophila (50–10%, OAI: − 0.82 to − 0.52). Xenorhabdus szentirmaii, X. doucetiae, and P. kayaii showed significant deterrence at ≥ 20% concentrations. Using promoter exchange mutants generated by the easyPACId approach, fabclavine from X. szentirmaii was identified as the bioactive compound with evident deterrent effects. Such deterrents targeting egg-laying could be valuable for controlling populations by disrupting their breeding in suitable habitats.

Black blow fly (Diptera: Calliphoridae) bacterial symbionts inform oviposition site selection by stable flies (Diptera: Muscidae).

Larval habitats of blood-feeding stable flies, Stomoxys calcitrans (L.) (Diptera: Muscidae), overlap with foraging sites of black blow flies, Phormia regina (Meigen) (Diptera: Calliphoridae). We tested the hypothesis that bacteria in blow fly excreta inform oviposition decisions by female stable flies. In laboratory 2-choice bioassays, we offered gravid female stable flies fabric-covered agar plates as oviposition sites that were kept sterile or inoculated with either a blend of 7 bacterial strains isolated from blow fly excreta (7-isolate-blend) or individual bacterial isolates from that blend. The 7-isolate-blend deterred oviposition by female stable flies, as did either of 2 strains of Morganella morganii subsp. sibonii. Conversely, Exiguobacterium sp. and Serratia marcescens each prompted oviposition by flies. The flies' oviposition decisions appear to be guided by bacteria-derived semiochemicals as the bacteria could not be physically accessed. Oviposition deterrence caused by semiochemicals of the 7-isolate-blend may help stable flies avoid competition with blow flies. The semiochemicals of bioactive bacterial strains could be developed as trap lures to attract and capture flies and deter their oviposition in select larval habitats.

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.

Anti-dengue potential and mosquitocidal effect of marine green algae-stabilized Mn-doped superparamagnetic iron oxide nanoparticles (Mn-SPIONs): an eco-friendly approach.

Vector-borne diseases pose a significant public health challenge in economically disadvantaged nations. Malaria, dengue fever, chikungunya, Zika, yellow fever, Japanese encephalitis, and lymphatic filariasis are spread by mosquitoes. Consequently, the most effective method of preventing these diseases is to eliminate the mosquito population. Historically, the majority of control programs have depended on chemical pesticides, including organochlorines, organophosphates, carbamates, and pyrethroids. Synthetic insecticides used to eradicate pests have the potential to contaminate groundwater, surface water, beneficial soil organisms, and non-target species. Nanotechnology is an innovative technology that has the potential to be used in insect control with great precision. The goal of this study was to test the in vitro anti-dengue potential and mosquitocidal activity of Chaetomorpha aerea and C. aerea-synthesized Mn-doped superparamagnetic iron oxide nanoparticles (CA-Mn-SPIONs). The synthesis of CA-Mn-SPIONs using C. aerea extract was verified by the observable alteration in the colour of the reaction mixture, transitioning from a pale green colour to a brown. The study of UV-Vis spectra revealed absorbance peaks at approximately 290nm, which can be attributed to the surface Plasmon resonance of the CA-Mn-SPIONs. The SEM, TEM, EDX, FTIR, vibrating sample magnetometry, and XRD analyses provided evidence that confirmed the presence of CA-Mn-SPIONs. In the present study, results revealed that C. aerea aqueous extract LC50 values against Ae. aegypti ranged from 222.942 (first instar larvae) to 349.877ppm in bioassays (pupae). CA-Mn-SPIONs had LC50 ranging from 20.199 (first instar larvae) to 26.918ppm (pupae). After treatment with 40ppm CA-Mn-SPIONs and 500ppm C. aerea extract in ovicidal tests, egg hatchability was lowered by 100%. Oviposition deterrence experiments showed that in Ae. aegypti, oviposition rates were lowered by more than 66% by 100ppm of green algal extract and by more than 71% by 10ppm of CA-Mn-SPIONs (oviposition activity index values were 0.50 and 0.55, respectively). Moreover, in vitro anti-dengue activity of CA-Mn-SPIONs has good anti-viral property against dengue viral cell lines. In addition, GC-MS analysis showed that 21 intriguing chemicals were discovered. Two significant phytoconstituents in the methanol extract of C. aerea include butanoic acid and palmitic acid. These two substances were examined using an in silico methodology against the NS5 methyltransferase protein and demonstrated good glide scores and binding affinities. Finally, we looked into the morphological damage and fluorescent emission of third instar Ae. aegypti larvae treated with CA-Mn-SPIONs. Fluorescent emission is consistent with ROS formation of CA-Mn-SPIONs against Ae. aegypti larvae. The present study determines that the key variables for the successful development of new insecticidal agents are rooted in the eco-compatibility and the provision of alternative tool for the pesticide manufacturing sector.

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

A review of botany, traditional applications, phytochemistry, pharmacological applications, and toxicology of Rubus ellipticus Smith fruits.

Rubus ellipticus Smith. (Family Rosaceae), often known as the yellow Himalayan raspberry (Yellow Hissar), is one of the most widely used edible fruits in Indian folk medicinal systems. The current review aims to identify the gap between research and existing applications of this fruit to help scientists explore the current trends and opportunities for future development. Fruits of R. ellipticus are the source of several classes of compounds. Fruits of R. ellipticus are also rich in nutrients such as carbohydrates, vitamins, and minerals. It has been shown to have significant medical value in a variety of studies, including as an anti-diabetic, nephroprotective, anti-inflammatory, analgesic, antipyretic, antitumor, wound healing, antifertility, oviposition deterrent, antibacterial, and antioxidant. Fruits of R. ellipticus have been the subject of several in vitro and in vivo investigations, all of which have corroborated their wide range of biological activities and demonstrated their potential for the identification of new therapeutic candidates and the development of innovative herbal food supplements. Additional mechanism-based pharmacological evaluation and clinical research shouldprovide an adequate scientific basis for the traditional usage of R. ellipticus fruits, which is currently not sufficiently supported by the available research on its active components and molecular mechanisms.

Ovipositional responses of tortricid moths to sugars, salts and neem oil

Oviposition is essential in the life history of insects and is mainly mediated by chemical and tactile cues present on the plant surface. Oviposition deterrents or stimulants can modify insect oviposition and be employed in pest control. Relatively few gustatory oviposition stimuli have been described for tortricid moths. In this study the effect of NaCl, KCl, sucrose, fructose and neem oil on the number of eggs laid by Cydia pomonella (L.), Grapholita molesta (Busck) and Lobesia botrana (Dennis & Schifermüller) was tested in laboratory arenas containing filter papers loaded with 3 doses of a given stimulus and solvent control. In general, salts increased oviposition at the mid dose (102 M) and sugars reduced it at the highest dose (103 mM), but these effects depended on the species. Neem oil dramatically reduced the number of eggs laid as the dose increased, but the lowest neem oil dose (0.1% v/v) increased L. botrana oviposition relative to solvent control. Our study shows that ubiquitous plant chemicals modify tortricid moth oviposition under laboratory conditions, and that neem oil is a strong oviposition deterrent. The oviposition arena developed in this study is a convenient tool to test the effect of tastants on the oviposition behavior of tortricid moths.

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.

Efficacy of essential oils from three Mentha species against postharvest groundnut pest, Caryedon serratus (Olivier) (Coleoptera: Bruchidae)

Indiscriminate use of chemical pesticides has resulted in many negative implications including degradation of the ecosystem, contamination of food products and effect on non-target organisms. Biopesticides is an efficient and ecofriendly alternative to these synthetic pesticides. Herein, we explored the efficacy of plant-extracted essential oils as a natural alternative to manage groundnut pests. Essential oils extracted from three Mentha species (M. arvensis, M. piperita and M. spicata) were detected for their chemical composition, oviposition deterrence, repellency and electrophysiological responses in groundnut bruchid, Caryedon serratus (Olivier). Gas chromatographic analysis revealed menthol (M. arvensis: 30.43%, M. piperita: 30.18%) and carvone (M. spicata: 65.58%) as the most abundant component in essential oils. Among all the four tested concentrations for the three mentha oils the most significant oviposition deterrence was seen in M. spicata (2% v/w) which completely inhibited oviposition followed by 1.5% M. piperita (21 ± 1.53; p < 0.01), 1.5% M. spicata (28 ± 0.58; p < 0.01) and 1.0% M. arvensis (35 ± 0.58; p < 0.01) oil treated groundnuts after 24 h. M. piperita (86%, ♀) and M. arvensis (70%, ♀) showed promising repellence against the females. In contrast, M. spicata was found to be a potent (90%, ♂) male repellent during olfactometer bioassays. Coupled gas chromatography electroantennogram (GC-EAG) revealed consistent sensory deflections in the antennae of female C. serratus from all the three oils. Our findings revealed promising oviposition deterrence and repellent properties of these mentha oils which offers a prospect in developing effective repellent and its application in integrated pest management, safety of human health, environment and agricultural productivity.