Oviposition Deterrent Research Articles

Oviposition deterrence, larvicidal activity and docking of β-germacrene-D-4-ol obtained from leaves of Piper corcovadensis (Piperaceae) against Aedes aegypti

The present study compared the chromatographic profile of oils from P. corcovadensis leaves obtained through hydrodistillation, maceration, supercritical fluid, headspace, steam distillation and ultrasound to determine the best method for the obtainment of β-germacrene-D-4-ol. The oviposition deterrent and larvicidal activities of this compound were carried out. The main compounds identified in the oils obtained using these methods were terpinolene, 1-butyl-3,4-methylenedioxybenzene, trans-caryophyllene and β-germacrene-D-4-ol, the proportions of which varied with the extraction method employed. Steam distillation (26.48 ± 0.37%), maceration (25.26 ± 0.39%) and supercritical fluid (24.38 ± 0.47%) were the best methods for extracting β-germacrene-D-4-ol. The oil obtained by maceration had the highest yield and was therefore chosen for the isolation of β-germacrene-D-4-ol. Larvicidal and oviposition assays of isolated compound and the oil obtained by maceration were performed with A. aegypti. Larvicidal activity (LC50) were 18.23 ± 1.19 ppm for β-germacrene-D-4-ol and 6.71 ± 0.16 ppm for the oil. The compound and oil also exhibited oviposition deterrence activity against the mosquito at concentrations of 5, 10 and 50 ppm. Moreover, it could be assumed that the sesquiterpene β-germacrene-D-4-ol achieves oviposition deterrence by interacting with odorant-binding protein 1 (OBP1) in Aedes aegypti, as the highest FitScore was found for this macromolecular target. This suggests how mosquito identifies β-germacrene-D-4-ol at the oviposition site. The findings demonstrate that β-germacrene-D-4-ol and the P. corcovadensis leaf oil obtained by maceration have considerable potential as larvicides and oviposition deterrents for the control of the A. aegypti.

Toxicity and Compatibility of Botanical Insecticide From Clove (Syzygium Aromaticum), Lime (Citrus Aurantifolia) and Garlic (Allium Sativum) Essential oil Against Callasobruchus Chinensis L

Cowpea beetle of Callosobruchus chinensis (Coleoptera: Bruchidae) is one of the primary storage pests of green beans that can reduce the beans’ quality and quantity. Plant essential oils are known to have insecticidal activity against insect pests. The study aims to investigate the toxicity, oviposition deterrence, and compatibility of botanical insecticides formulas of Syzygium aromaticum, Citrus aurantifolia, and Allium sativum essential oils to C. chinensis. The essential oils were obtained by distillation method. Contact and fumigant methods were used to test the toxicity of the oils. The toxicity levels (LC50 and LC95) were analyzed. The three essential oils tested were toxic and also had oviposition deterrent to C. chinensis. A. sativum essential oil showed the highest toxic (LC50=0.07%, LC95 = 0.89%), followed with S. aromaticum (LC50 = 0.08%, LC95 = 0.95%), and C. aurantifolia (LC50 = 0.07%, LC95 = 1.21%) after 72 h contact exposure to the adults. The three essential oils also showed an oviposition deterrence. A. sativum and S. aromaticum essential oils mixture at a ratio of 1:1 showed the strongest synergistic interaction to C. chinensis. The study suggests that the essential oil formula could be developed as a potential botanical insecticide.

Morphometric, molecular characterization and management of Callosobruchus chinensis

Pulse beetle, Callosobruchus chinensis L. (Coleoptera: Chrysomelidae) is the most economic insect pest of pulse and can cause huge quantitative losses and also decreases the nutritional value of stored products. The morphological and molecular characterization of pulse beetles was determined and different non-edible oils against C. chinensis were assessed at ICAR-National Bureau of Plant Genetic Resources, New Delhi during 2019–20. Eggs of C. chinensis were 264.74±3.716 μm in width and 452.33±4.531 μm in length. The final instar larva of C. chinensis was 1703.12±4.692 μm in width and 3062.19±33.119 μm in length. The width and length of the pupae was 1696.09±5.589 μm and 3281.60±73.641 μm, respectively. The length of the adult body was 2520.85±23.278 μm for females and 2469.70±29.570 μm for males with a width of 1426.78±41.334 μm for females and 1456.54±23.606 μm for males. Both C. maculatus and C. chinensis got amplified by COI primer. A band of approximately 710 bp was obtained from both pulse beetles (C. maculatus and C. chinensis). DNA barcode helps in identification of pests at all life stages. Hundred per cent of egg mortality, larval mortality and adult mortality were reported in all non-edible oils such as Pongamia glabra L., Hydnocarpus wightiana Blume, Madhuca longifolia Konig, Callophyllum inophyllum L. and Azadirachta indica A. Juss. Similarly, all non-edible oils had ovipositional deterrence. To summarize, these oils can be used for the management of pulse beetles during storage.

Bioefficacy of plant oils applied through wooden cube impregnation against pulse beetle, Callosobruchus maculatus (F.) in green gram

Aim: To assess the bioefficacy of plant oils against pulse beetle, Callosobruchus maculatus (F.) in green gram through wooden cube impregnation. Methodology: Bioefficacy of plant oils viz; clove, sweet flag, eucalyptus, orange, cedar wood and neem at two doses, i.e., 0.5 ml and 1.0 ml dispensed through a small wooden cube was assessed against the pulse beetle in green gram. The oils except neem are essential oils. A wooden cube impregnated with plant oil was placed over the grain surface and ten pairs of adult insects were released into each treatment. Data on oviposition, adult emergence and grain damage was recorded in each treatment. Insect mortality due to fumigant effect of plant oil at 0.5 ml per cube was also observed. Results: There was no oviposition by pulse beetles in clove, sweet flag, and eucalyptus oil treatments at 0.5 ml against the untreated control which recorded 14 eggs/100 grains. Consequently, no population buildup was observed in clove, sweet flag, eucalyptus and orange oil treatments after 120 days. A total of 2313.33 adults emerged from the untreated green gram inflicting 46.67 percent grain damage. In fumigant toxicity test, hundred per cent mortality of pulse beetle adults was observed with orange oil in 48 hr of treatment and with eucalyptus oil in 72 hr at 0.5 ml. The results indicated that the plant oils showed strong oviposition deterrence as well as insecticidal activity against the pulse beetle. Thus, application of essential oils through a wooden cube was found highly effective to keep away the pulse beetles. Interpretation: Essential oils of clove, sweet flag, eucalyptus and orange when applied through wooden cube impregnation at a dose as low as 0.5 ml showed strong oviposition deterrence and insecticidal activity against pulse beetle. The insecticidal activity of oils can be attributed to the fumigant action and can be used effectively to prevent pulse beetle infestation in grain legumes.

Contact Toxicity and Ovideterrent Activity of Three Essential Oil-Based Nano-Emulsions against the Olive Fruit Fly Bactrocera oleae

The control strategies for the olive crop key pest, Bactrocera oleae, involve synthetic chemical insecticides and few eco-sustainable alternatives, such as ovideterrents and lures. In the last few decades, the interest concerning the formulation of botanical based biopesticides increased, but little research investigated the suitability of these approaches for B. oleae control. This research aimed to investigate the residual contact toxicity and the oviposition deterrence of three essential oil (EO)-based nano-emulsions (Pimpinella anisum, Foeniculum vulgare, Mentha × piperita) against B. oleae adult flies. All the nano-emulsions possessed optimal physical characteristics, with droplets dimensions ranging from 115 to 152 nm and low PDI values (<0.2), even after 1 year of storage. Although no notable residual contact toxicity was noted, all the tested formulations reduced the number of oviposition puncture in no-choice tests (percent repellence: mint < fennel < anise). In choice trials, olives treated with fennel and anise EO-formulations at the highest concentration (7.5%, 75 g of EO/L) were less attractive respect to control fruits and a significant reduction of olive punctures was recorded. Nano-biopesticides are promising eco-friendly tools to integrate B. oleae pest management programs and to reduce the use of harmful conventional active ingredients.

Methyl Benzoate as a Promising, Environmentally Safe Insecticide: Current Status and Future Perspectives

The widespread use of synthetic chemical pesticides beginning in the late 1930s has contributed to the development of insecticide resistance of many important species of pest insects and plants. Recent trends in pesticide development have emphasized the use of more environmentally benign control methods that take into consideration environmental, food safety, and human health. Biopesticides (e.g., naturally occurring pesticidal compounds) are alternative pest management tools that normally have no negative impact on human health or the environment. Here we review methyl benzoate, a relatively new botanical insecticide that occurs naturally as a metabolite in plants, and whose odor is an attractant to some insects. Since 2016, many studies have shown that methyl benzoate is an effective pesticide against a range of different agricultural, stored product, and urban insect pests. Methyl benzoate has several important modes of action, including as a contact toxicant, a fumigant, an ovicidal toxin, an oviposition deterrent, a repellent, and an attractant. In this review, we summarize various modes of action of methyl benzoate and its toxicity or control potential against various kinds of arthropods, including agricultural pests and their natural enemies, and pollinators. We conclude that methyl benzoate is a very promising candidate for use in integrated pest management under either greenhouse or field conditions.

Chemical Composition, Insecticidal, Persistence and Detoxification Enzyme Inhibition Activities of Essential Oil of Artemisia maritima against the Pulse Beetle.

Pulse beetle is the major pests of pulses that cause significant loss to grains leads to unfit for consumption and marketing. Indiscriminate use of synthetic pesticides for the control of pulse beetle (Callosobruchus chinensis and Callosobruchus maculatus) led to insect resistance, pesticide residues on grains which affect consumer’s health and environment. Essential oils (EOs) are good alternatives to synthetics due to their safety to the environment and consumers’ health. The main objective of the present study was to explore the chemical composition, fumigant, repellency, ovipositional deterrence, persistence, and detoxification enzyme inhibition of Artemisia maritima essential oil against pulse beetle. Results showed that primary components of the EO were 1,8-Cineole and bornyl acetate. EO showed promising fumigant toxicity to C. chinensis and C. maculatus (LC50 = 1.17 and 0.56 mg/L, respectively) after 48 h. In the repellent assay, EO at 8 mg/L showed 92–96% repellence after 1 h. In ovipositional deterrence assay, EO showed more ovipositional deterrence against C. chinensis (OD50 = 3.30 mg/L) than C. maculatus (OD50 = 4.01 mg/L). Higher concentrations of oil (8 and 6 mg/L) in C. maculatus showed significant inhibition of the glutathione-S-transferase enzyme (7.14 and 5.61 n mol/min/mL, respectively).

Larvicidal activity against Aedes aegypti and molecular docking studies of compounds extracted from the endophytic fungus Aspergillus sp. isolated from Bertholletia excelsa Humn. & Bonpl.

Endophytic fungi are microorganisms capable of colonizing the interior of plant tissues without causing damage to them. The study of the secondary metabolites produced by their vast biodiversity fungal is relevant for the discovery of new products for biotechnological and agrochemical applications. In addition, extract of the endophytic fungus Aspergillus sp., isolated from the almonds of Bertholletia excelsa Humn & Bonlp collected in the Brazilian Amazon, oviposition deterrent, and larvicidal activity of against Aedes aegypti. In the oviposition deterrence test was observed that females able to lay eggs preferred the control oviposition sites (46.6%). Furthermore, the extract showed larvicidal activity with LC50 26.86µg/mL at 24h and 18.75µg/mL at 48h. Molecular docking studies showed the compound Aspergillol B a potent larvicide by to inhibit the acetylcholinesterase enzyme (- 7.74kcal/mol). These results indicate that compounds from secondary metabolites of Aspergillus sp., isolated from almonds of B. excelsa, are useful biological potential against vectors A. aegypti.

Oviposition behaviour and biochemical response of an insect pest, Zeugodacus cucurbitae (Coquillett) (Diptera: Tephritidae) to plant phenolic compound phloroglucinol

Phenolic compounds are the secondary metabolites (SMs) present in plants carrying different bioactivities. In the present study, we explored the influence of a phenolic compound namely phloroglucinol on oviposition behaviour and different biochemical entities of an insect pest Zeugodacus cucurbitae (Coquillett) (Diptera: Tephritidae) using artificial diet. Phloroglucinol (IUPAC name: benzene-1,3,5-triol) affected the activity of antioxidant and detoxifying enzymes viz. superoxide dismutases (SOD), catalase (CAT), ascorbate peroxidases (APOX). dehydroascorbate reductase (DHAR), peroxidases (POX), phenol oxidase (PO), glutathione peroxidase (GPOX), glutathione S-transferase peroxidase (GSTpox), glutathione reductase (GR), glutathione S-transferase (GST) and esterases (EST) as well as the biological antioxidants viz. ascorbate content and glutathione. The lipid peroxide content (LP) and hydrogen peroxide content (H2O2) were significantly enhanced in the treated larvae indicating oxidative stress in the insect. Significant inhibition in oviposition was observed and effective repellency percentage increased with phloroglucinol treatment as compared to control. The oviposition deterrent activity and toxic effects of phloroglucinol on various biochemical parameters of Z. cucurbitae larvae revealed in the present study clearly confirms its suitability for use in pest management.

New challenges demand new solutions: Selected essential oils as an alternative to control Bemisia tabaci MED in Brazil

The introduction of Bemisia tabaci Mediterranean (MED) (Gennadius) (Hemiptera: Aleyrodidae) (Biotype Q) into Brazil has attracted the attention of farmers and the scientific community as this species has a high capacity for infestation and high tolerance to conventional insecticides. As an alternative to chemical control, botanical derivatives stand out as a valuable tool for integrated pest management (IPM). In this context, this work evaluated for the first time the bioactivity of essential oils of Piper marginatum Jacq. (Piperaceae) (PM-EO) and Mansoa alliaceae (Lam.) A.ww H. Gentry (Bignoniaceae) (MA-EO) against B. tabaci MED. First, concentration-mortality bioassays were performed to estimate the lethal concentrations (LCs) on nymphs of B. tabaci MED. The LC50s and LC90s were tested in multi-choice assays (repellency and oviposition deterrence) and no-choice assays (ovicidal effects and infestation ability). Finally, assays were carried out in a greenhouse to check the efficiency of the essential oils under semifield conditions. The major compounds identified in PM-EO were (E)-methyl eugenol (34.7%) and (Z)-methyl eugenol (27.5%), while diallyl trisulfide (52.8%) and diallyl disulfide (33.9%) were the major compounds in MA-EO. The EOs were toxic against nymphs in the laboratory and greenhouse and showed ovicidal effect and repellent action. The EOs also reduced oviposition and inhibited the colonization by B. tabaci MED. Our results reveal two promising sources of botanical pesticides to control B. tabaci MED. These compounds can cause lethal and sublethal effects in all insect life stages, increasing the control efficiency.

Identification of volatiles from larval faecal pellets of Indian strain of fall armyworm, Spodoptera frugiperda (J.E. Smith)

The present study was carried out to identify the volatiles from larval faecal pellets of fall armyworm and to explore these in novel semiochemical based pest management options like oviposition deterrents. The volatiles were identified from larval faecal pellets of fall armyworm reared on maize under laboratory conditions. Samples were prepared using methanol as solvent and analysed in GC-MS. In the present study, total thirteen volatiles have been identified from methanol extract of faecal pellets. On the basis of percent area, the individual compound has been categorized as major (>10%), minor (1–10%) and negligible (<1%). Among identified compounds, three volatiles; namely hexadecanoic acid methyl ester, 9-octadecenoic acid (Z)- methyl ester, 9-octadecenoic acid (E)- methyl ester constituted more than 70% were major compounds. Minor compounds include 9,12-octadecadienoic acid (Z,Z)- methyl ester, methyl stearate, phytol, 9-hexadecenoic acid methyl ester (Z), and pentadecanoic acid methyl ester comprising 26.43% area in total, along with negligible amounts of tetradecanoic acid 12-methyl methyl ester (S), hexadecanoic acid 14-methyl methyl ester, methyl tetradecanoate, octadecanoic acid 10-methyl methyl ester and neophytadiene constituting 3.16% of total area. Plant derived components phytol and neophytadiene were identified as the larvae were reared on plant parts.

Assessment of toxicity of different doses of acetamiprid 20 SP to the egg parasitoid, Trichogramma chilonis (Ishii) (Hymenoptera: Trichogrammitidae)

The results revealed that the effect of acetamiprid 20 SP on T. chilonis @ 10, 20, 40 and 80 g a.i./ha was less adverse on adult emergence after 24 h (69.00 and 77.00%) and 48 h (81.33 and 91.00%) of treatment while standard check, monocrotophos 36 SL @ 200 g a.i./ha was relatively more toxic when compared to untreated check after 24 and 48 h of treatment. Moreover, the highest parasitisation (81.00 and 91.33%) was recorded in the untreated check which differed significantly from other treatments followed by acetamiprid 20 SP at 10 g a.i./ha (73.00 and 86.00%). Overall acetamiprid did not show any ovipositional deterrence and T. chilonis, recorded more than 72.00% parasitism. Similarly adult emergence was also not affected and also there was no ill effect on the developing parasitoids and emerged adults.

Bioefficacy of plant extracts on ovicidal and oviposition deterrent against sugarcane stalk borer Chilo auricilius Dudgeon (Lepidoptera: Crambidae)

Sugarcane is a long-duration crop of 10-12 months and therefore is liable to be attacked by several insect pests. The present study aimed at assessing the ovicidal, oviposition, and larvicidal potential of two medicinal indigenous plants. Bioefficacy of Nerium indicum Mill. and Murrya koenigii L. spreng leaves extracts were tested against Chilo auricilius D. sugarcane stalk borer. The plant extracts prepared by sequential extraction method using a different solvent like, petroleum, chloroform, methanol, distilled water, and acetone at different concentrations were used. Ovipositional behavior of adult moths and the hatching percentage of the eggs were recorded using the choice method for each fraction of the plant extract. The chloroform extract of N. indicum 2.66% eggs/female and chloroform/petroleum ether extracts of M. koenigii 9.33% eggs/female were found to be effective, and reduced oviposition as compared to other extracts. At 20% concentration, petroleum ether and distilled water extracts of N. indicum 52.00 and petroleum ether extract of M. koenigii gave the lowest larval survival (74.00,72.00 and 70.00%) after 24, 48, and 72 h of exposures, respectively. However, petroleum ether extract of N. indicum at 8, 10, and 20% concentration survival of three days old eggs were registered at 60, 58, and 56%, whereas petroleum ether extract of M. koenigii at similar concentration recorded 77, 47, and 72% survival.

Oviposition Deterrence and Ovicidal Activity of Birbira (Melletia furrgunia) on Diamondback Moth (Plutella xylostella) (Lepidoptera: Plutellidae)

The efficacy of different polar and non-polar solvent extracts of Birbira, Melletia furrginea (Hochst.) Baker tree seeds namely: Water, Acetic acid, Acetone, Chloroform, Toluene, and Hexane at different rates were evaluated on Diamondback moth, Plutella xylostella L. oviposition and egg mortality under laboratory conditions. The leaf dipping method was used to run both assays. In the assay, full Oviposition deterrence was recorded at the higher rates of polar solvent extracts. Significantly higher egg un-hatchability was recorded only at the higher rates for non-polar extracts. Eggs mortality caused by extracts with Water and Acetone was very high, and have much smaller LC50 values. In contrast, LC50 was higher for the other extracts. However, there was a constant increase in the percent kill of egg mass with the increase in the extract concentration. From this study, it is evident that M. furrgunia extracts with different solvents possess significant oviposition deterrence and ovicidal effect on P. xylostella.

Biological activities and chemical composition of Mentha piperita and Syzygium aromaticum essential oil fractions against cowpea weevil, Callosobruchus maculatus (Fabricius) (Coleoptera: Bruchidae)

Callosobruchus maculatus (Fabricius) is one of the major, common, pests of stored grains as it causes quantitative and qualitative losses in legume crops. This research sought to find the most active fraction in Mentha piperita and Syzygium aromaticum essential oils, to evaluate bioactivity of those crude essential oils and active fractions against C. maculatus, and to identify the compounds contained in the active fraction. The essential oils were fractionated using three solvents, namely n-hexane, ethyl acetate, and methanol. The n-hexane fraction was identified as the active fraction, causing mortality, oviposition deterrence, and ovicidal effects. In fumigation chambers, LD95 values of M. piperita (Mnf) and S. aromaticum n-hexane fractions (Snf) were 0.045 ml/l and 0.057 ml/l respectively. ED50 values for oviposition deterrence were 0.016 ml/l for Mnf and 0.022 ml/l for Snf. ED50 value of ovicidal effects for Mnf- and Snf-treated eggs were 0.014 ml/l for both fractions. GC-MS analysis showed 8 dominant compounds in Mnf and 5 dominant compounds in Snf. Overall it is concluded that Mnf and Snf oils have effective biological activities against stored pest C. maculatus and have potential to be considered as alternatives to synthetic insecticides.

Bioactivities of Lamiaceae, Myristicaceae, and Myrtaceae plant oils against Nilaparvata lugens Stâl. (Hemiptera: Delphacidae)

Essential oil (EO) plants have properties as botanical insecticides. Some of them come from the families of Lamiaceae, Myristicaceae, and Myrtaceae. A plant belonging to the Lamiaceae includes patchouli (Pogostemon cablin), while the Myristicaceae includes nutmeg (Myristica fragrans), and the Myrtaceae includes clove (Syzygium aromaticum) and cajuput (Melaleuca cajuput subsp. cajuputi). This research aimed to evaluate toxicity, feeding inhibition, and oviposition deterrent from four EO plants from the Lamiaceae, Myristicaceae, and Myrtaceae to brown rice planthopper Nilaparvata lugens (Hemiptera: Delphacidae), the main pest of rice. The results showed that cajuput and patchouli oil gave more potent toxicity to N. lugens with LC50 and LC95 were 0.016% and 4.87% for cajuput oil and 0.019% and 5.25% for patchouli oil. Cajuput oil at 0.002% deterred oviposition 51.74% and inhibited feeding on 0.016% as many as 71.52% with strong enough criteria to the fourth instar nymphs of N. lugens. Patchouli oil deterred oviposition from 0.002% as much as 61.15% and inhibited feeding on 0.019% as many as 68.73% with strong enough criteria. The highest oviposition deterrent was 83.2% on patchouli oil at the concentration of 0.188%, whereas the highest feeding inhibition was 82.78% on cajuput oil at the concentration of 0.169%.

Lethal and Sublethal Effects of Annona spp. Derivatives on Bemisia tabaci MEAM 1 (Hemiptera: Aleyrodidae) in Tomato.

The whitefly Bemisia tabaci(Gennadius) MEAM 1 is one of the main insect species that colonize tomato plants and cause direct and indirect damage. The use of botanical derivatives may be a valuable method of insect control to reduce the inappropriate use of synthetic insecticides on crops. In this study, we evaluated the bioactivity of ethanolic extracts prepared from Annonaceae species compared to that of the commercial insecticides based on acetogenins (Anosom® 1 EC, anonine 10,000 mg L-1) and thiamethoxam (Actara® 250 WG) on eggs, nymphs, and adults of the whitefly in tomato. Initially, the effects of the ethanolic seed extracts of Annona mucosa (Jacq.), Annona muricata L., and Annona sylvatica A.St.-Hil on adult insect behavior were evaluated. The rates of infestation and oviposition deterrence indicated the inhibitory effects of the extract of A. muricata (500 mg L-1). Then, the possible systemic effects of the extracts were evaluated; however, no effects on nymphal development or insect viability were observed. The LC50 and LC90 of the ethanolic extract of A. mucosa seeds at 500 mg L-1 (10.83 and 200.24 mg L-1, respectively) were estimated and were used in ovicidal tests and compared to positive (Actara® 250 WG and Anosom® 1 EC), and negative controls (water: acetone, 1:1 v/v). At LC90, fewer eggs (35.00%) had hatched at 13 days after application than in the other treatments. The results of this study demonstrate the potential use of botanical derivatives of Annona spp. for the management of B. tabaci MEAM 1 in tomato.

Oviposition Deterrence of Fruit fly in Treated Mangoes with Ant cues and Fungus B. bassiana

Bacterocera zonata is a very serious pest of fruit crops especially mangoes over the globe. The present study was conducted to observe oviposition deterrence in B. zonata under lab conditions. Mangoes (Desi, Chaunsa and Anwar Ratool) were treated with ant cues and entomopathogenic Beauveria bassiana. Oviposition deterrence was recorded when nonspecific and variety specific (Chaunsa, Anwar Ratol) mangoes were treated with ant cues and B. bassiana at different intervals (exposure to 4 days). It showed that the mean number of oviposition punctures tend to increase with time. Minimum fruits puncture was found at day 1 in B. bassiana treated mangoes, while at 4th day, maximum number of punctures were observed in untreated mangoes. B. bassiana treated mangoes showed minimum number of punctures than ant cues and untreated mangoes were observed with highest number of punctures.

Detecting the Conspecific: Herbivory-Induced Olfactory Cues in the Fall Armyworm (Lepidoptera: Noctuidae).

The fall armyworm (FAW), Spodoptera frugiperda (Smith), is a polyphagous pest whose larval feeding threatens several economically important crops worldwide with especially severe damage to corn (Zea mays L.). Field-derived resistance to several conventional pesticides and Bt toxins have threatened the efficacy of current management strategies, necessitating the development of alternative pest management methods and technologies. One possible avenue is the use of volatile organic compounds (VOCs) and other secondary metabolites that are produced and sequestered by plants as a response to larval feeding. The effects of conspecific larval feeding on fall armyworm oviposition preferences and larval fitness were examined using two-choice oviposition experiments, larval feeding trials, targeted metabolomics, and VOC analyses. There was a significant preference for oviposition on corn plants that lacked larval feeding damage, and larvae fed tissue from damaged plants exhibited reduced weights and head capsule widths. All larval feeding promoted significantly increased metabolite and VOC concentrations compared to corn plants without any feeding. Metabolite differences were driven primarily by linoleic acid (which is directly toxic to fall armyworm) and tricarboxylic acids. Several VOCs with significantly increased concentrations in damaged corn plants were known oviposition deterrents that warrant further investigation in an integrated pest management context.

Zea mays Volatiles that Influence Oviposition and Feeding Behaviors of Spodoptera frugiperda.

Fall armyworm (Spodoptera frugiperda) is a major global pest of many crops, including maize (Zea mays). This insect is known to use host plant-derived volatile organic compounds to locate suitable hosts during both its adult and larval stages, yet the function of individual compounds remains mostly enigmatic. In this study, we use a combination of volatile profiling, electrophysiological assays, pair-wise choice behavioral assays, and chemical supplementation treatments to identify and assess specific compounds from maize that influence S. frugiperda host location. Our findings reveal that methyl salicylate and (E)-alpha-bergamotene are oviposition attractants for adult moths but do not impact larval behavior. While geranyl acetate can act as an oviposition attractant or repellent depending on the host volatile context and (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT) is an oviposition deterrent. These compounds can also be attractive to the larvae when applied to specific maize inbreds. These data show that S. frugiperda uses different plant volatile cues for host location in its adult and larval stage and that the background volatile context that specific volatiles are perceived in, alters their impact as behavioral cues.