Search Results (40)

The melon fly, Zeugodacus cucurbitae (Coquillett), is a globally significant agricultural pest causing substantial economic losses. Odorant-binding proteins (OBPs) are critical of the insect olfactory system, yet their specific physiological functions in Z. cucurbitae remain largely uncharacterized. In this study, we functionally characterized ZcucOBP14 and investigated its putative involvement in host chemoreception and insecticide tolerance. Sequence alignment and phylogenetic analysis indicated that ZcucOBP14 belongs to the Minus-C OBP subfamily, and quantitative reverse transcription PCR (RT-qPCR) showed that it was predominantly expressed in both the head and abdomen. Fluorescence binding assays revealed that ZcucOBP14 exhibited broad binding affinity to 11 host plant volatiles, three sex pheromones, and two insecticides. Subsequent electroantennography (EAG) and behavioral bioassays identified isopulegol, 1-hexanol, linalool, and α-pinene as key ligands regulating the behavioral responses of Z. cucurbitae. RNA interference (RNAi)-mediated knockdown of ZcucOBP14 significantly reduced EAG responses to key ligands, eliminated behavioral preference, and increased insecticide-induced mortality by 20%. Molecular docking further identified that Tyr71, Ile67, Trp50, Val107, Phe116 and Leu70 were critical residues involved in ligand interactions. Collectively, these findings highlight the indispensable role of ZcucOBP14 in olfactory perception and its contribution to insecticide tolerance, laying a solid theoretical foundation for the development of novel behavior-modifying agents, attractants, and optimized integrated pest management (IPM) strategies against this pest. Full article

Phthonoloba viridifasciata (Lepidoptera: Geometridae) is the primary herbivorous insect of the rare and endangered plant Alsophila spinulosa. The aim of this study was to investigate the host-seeking mechanism of P. viridifasciata by screening volatile compounds from A. spinulosa for their attractant or repellent activity, so as to provide a theoretical basis for its eco-friendly control. We used the dynamic headspace adsorption to collect the volatile compounds from A. spinulosa. A combination of Gas Chromatography–Electroantennography Detection (GC-EAD), Gas Chromatography–Mass Spectrometry (GC-MS), electroantennography (EAG), and Y-olfactometer bioassays was used to screen and identify active compounds that induce responses in P. viridifasciata. Five active volatile compounds induced significant electrophysiological activity, including decane, undecane, 4-ethylbenzaldehyde, m-ethylacetophenone, and p-ethylacetophenone. All five active compounds triggered EAG responses in both sexes. Behavioral bioassays further revealed that 4-ethylbenzaldehyde (10⁻² and 10⁻⁴ mol/L) and decane (10⁻⁵ mol/L) act as female attractants. Meanwhile, males showed a behavioral preference response to 4-ethylbenzaldehyde at 10⁻² mol/L. Full article

Butterflies locate host sites using plant volatiles, while larval frass cues induce avoidance. This study investigated the olfactory responses of adult Papilio polytes to nine shared plant and frass volatiles across 1 × 10³ to 1 × 10⁶ ng load doses using electroantennography (EAG) and Y-tube olfactometer assays. EAG responses were significantly influenced by chemical composition, dose, and sex, as well as all their interactions. In contrast, behavioral choices were significantly driven only by chemical composition and its interaction with dose. Although females exhibited higher peripheral sensitivity than males, this physiological sexual dimorphism did not result in significant behavioral differences. Linalool, citronellal, and geraniol were identified as the most potent elicitors. While their single forms and binary blends elicited attraction or neutrality, the ternary mixture significantly repelled both sexes. These results demonstrate that VOC blend composition determines the direction of behavioral responses, with linalool playing a pivotal role in the transition from attraction to avoidance. These findings highlight the importance of shared plant–frass VOCs in host selection by oligophagous insects and provide a foundation for manipulating P. polytes behavior. Full article

Rice volatiles play a crucial role in mediating resistance to the brown planthopper (Nilaparvata lugens Stål, Hemiptera: Delphacidae), a major pest of rice crops. In this study, we analyzed secondary metabolites from rice plants to identify compounds associated with insect behavior. A total of 31 volatile metabolites were detected, among which 16 differed significantly between 51 resistant or susceptible varieties. Fifteen volatiles were more abundant in susceptible plants, while one was enriched in resistant varieties. Electrophysiological (EAG) and Y-tube olfactometer assays revealed that both male and female adults exhibited positive chemotaxis toward five volatiles: Cyclohexanone, 2,2,6-trimethyl-; 3-Cyclohexen-1-one, 3,5,5-trimethyl-; (+)-Isomenthol; Benzoic acid, 2-hydroxy-, methyl ester; and 2-Methoxy-4-vinylphenol. In contrast, male adults were repelled by Benzaldehyde, 3-ethyl-, and 3-Buten-2-one, 4-(2,6,6-trimethyl-1-cyclohexen-1-yl)-. These results indicate that characteristic volatiles serve as functional cues for host selection and may act as phytochemical markers for assessing rice resistance. The findings provide new insights into plant–insect chemical interactions and suggest potential strategies for environmentally friendly pest management, including the use of attractant- or repellent-based approaches and breeding for optimized volatile profiles to control N. lugens. Full article

The Mediterranean fruit fly (Ceratitis capitata) is a globally invasive pest that affects a wide range of fruit and vegetable crops. Identifying cost-effective attractants is essential for sustainable integrated pest management (IPM). This study explored whether molecular docking, combined with electrophysiological recordings, can help prioritize structurally diverse compounds with potential relevance to medfly olfaction. We assessed the predicted interactions of more than 100 attractant-related and semiochemical compounds, including multiple stereoisomers, with 14 odorant-binding proteins (OBPs) and four odorant receptors (ORs). Trimedlure served as a benchmark ligand. Docking suggested that several sesquiterpenes may interact favorably with subsets of OBPs and ORs, although these predictions require biochemical validation. A small set of compounds with high predicted affinity, readily available in the laboratory, was further examined using electroantennography (EAG), which confirmed that selected sesquiterpenes elicited peripheral antennal activation in irradiated males. Overall, our results demonstrate the utility of computational screening as an exploratory tool for prioritizing candidate ligands and generating hypotheses about chemosensory processing in C. capitata. Integrating molecular modeling with biochemical and behavioral validation is a promising approach to developing next-generation IPM attractants. Full article

Tomicus brevipilosus Eggers is a major forest pest affecting Pinus yunnanensis Franch and Pinus kesiya var. Langbianensis (A.Chev.) Gaussen ex Bui in Southwest China. While attractants exist for related species, this study aimed to develop a more effective, tailored attractant for T. brevipilosus. We assessed the activity of host plant volatiles using electroantennography (EAG). Female and male beetles showed strong responses to different compounds: females to β-pinene, terpinolene, (+)-3-carene, and (R)-(+)-limonene; males to (+)-3-carene, 2-isopropyl-5-methylanisole, and D(+)-camphor. An optimized blend of these compounds achieved a high selection rate (57 ± 20%) in olfactory assays. This study represents a crucial preliminary investigation. The concentrations and release systems (rubber septa and centrifuge tubes) were optimized under controlled conditions to identify the most promising candidate for future scaling, rather than for immediate large-scale application. In semi-field cage bioassays, trap catch was highest at mid-canopy height (1.5 times branch-free height), under the cage canopy, and in treatments with low-to-moderate canopy density. This work provides a foundation for developing improved monitoring and management tools for T. brevipilosus. Full article

Bumblebees are important pollinating insects in crop pollination. Chemical attractants can effectively improve the flower-visiting efficiency of bumblebees, thereby increasing blueberry yields. To identify volatile compounds that attract bumblebees, we collected volatile compounds from blueberry flowers using headspace extraction. Gas chromatography– mass spectrometry (GC–MS) identified 32 volatile compounds, with Linalool and Styrene being the primary substances that accounted for 25.93% and 14.28%, respectively. The olfactory threshold of bumblebee antennae was assessed using electroantennography (EAG), and the behavioral responses from bumblebees were investigated using a Y-tube olfactometer. Results indicate that among the six classes of volatiles—alcohols, aldehydes, esters, ketones, aromatic compounds, and olefins—alcohols constituted the predominant proportion. Among these, six compounds—benzaldehyde, phenylpropylaldehyde, citral, linalool, α-terpineol, and geraniol—induced significant antennal responses in bumblebees. Our assays showed that geraniol, linalool, and α-terpineol at concentrations of 0.1 μg/μL, 1 μg/μL, and 10 μg/μL elicited attraction, whereas higher concentrations of benzaldehyde, benzenepropanal, and citral had repellent effects. Full article

Volatile cues are important in the host detection and discrimination of phytophagous insects, allowing them to find suitable hosts. Here, the electroantennography (EAG) and behavioral responses of female Thrips hawaiiensis to the floral volatiles of different plants, Magnolia grandiflora L. (Magnoliales: Magnoliaceae), Gerbera jamesonii Bolus (Asterales: Asteraceae), Lilium brownii Baker (Liliales: Liliaceae), and Rosa rugosa Thunb. (Rosales: Rosaceae), were studied. Y-tube olfactometer bioassays revealed that M. grandiflora was the preferred host for T. hawaiiensis. Fifty-two compounds were identified from the volatile profile of M. grandiflora by gas chromatography–mass spectrometry analysis, of which β-elemen (15.39%), bicyclogermacren (11.99%), and (E)-α-bisabolene (6.05%) showed the highest relative contents. The EAG bioassays revealed that the antennae of T. hawaiiensis could perceive these tested volatile compounds at different concentrations. In six-arm olfactometer bioassays, T. hawaiiensis showed significant positive responses to β-elemen and (E)-α-bisabolene at various concentrations, and 10 μg/μL was found to be the most attractive concentration for β-elemen, and 50 and 100 μg/μL for (E)-α-bisabolene. Based on the four-arm olfactometer bioassays, β-elemen was more attractive than (E)-α-bisabolene to T. hawaiiensis when compared at their optimal concentrations. Therefore, T. hawaiiensis could perceive and distinguish the floral volatiles from the preferred host plant (M. grandiflora). These findings assist in better understanding the mechanism of host preferences of T. hawaiiensis from a chemoecological perspective. In particular, β-elemen showed the greatest potential to be developed as a novel attractant for the monitoring and control of T. hawaiiensis. Full article

Thrips can be attracted or repelled by volatiles from different host plant species. Houttuynia cordata is a common plant species with a strong, offensive smell, and few pests have been detected on this plant. Here, the olfactory responses of Frankliniella occidentalis to H. cordata volatiles were tested using electroantennography (EAG) and behavioral bioassays in different types of olfactometers, and the behavioral responses of Orius similis, a natural enemy of F. occidentalis, to the related main volatile compounds were also evaluated. Y-tube olfactometer bioassays showed that F. occidentalis performed negative responses to H. cordata volatiles. Decanal (47.21%), 1-decanol (11.02%), dodecanal (7.13%), β-myrcene (5.12%), and decanoyl acetaldehyde (3.76%) were the more abundant components in the H. cordata volatile profile in gas chromatography–mass spectrometry analysis. EAG recordings showed that the antennae of female thrips could perceive these five compounds at a wide range of concentrations. In six-arm olfactometer bioassays, F. occidentalis exhibited negative responses to decanal, dodecanal, and decanoyl acetaldehyde at various doses but performed positive responses to 1-decanol and β-myrcene at certain doses. Furthermore, decanal, dodecanal, and decanoyl acetaldehyde at all concentrations showed no significant influences on the behavioral responses of O. similis. According to the results above, H. cordata can be a repellent plant species to F. occidentalis, and decanal, dodecanal, and decanoyl acetaldehyde show great potential for development as repellents for the control of F. occidentalis. In short, our results suggest that an integrated pest management system combining H. cordata-derived biopesticides with releases of the predator O. similis could effectively control F. occidentalis. Full article

Aphis gossypii Glover (Homoptera: Aphidinae), a major pest of Chinese pepper (Zanthoxylum bungeanum Maxim), causes significant agricultural damage. Ginger (Zingiber officinale Roscoe) has shown potential as a source for developing botanical pesticides due to its strong bacteriostatic and insecticidal properties; however, the underlying mechanisms remain poorly understood. This study evaluated the repellent activity of ginger shoot extract (GSE) across four solvent phases—petroleum ether, trichloromethane, ethyl acetate, and methanol—against A. gossypii. The results demonstrated that GSE exhibited significant repellent effects, with the methanol phase showing the most pronounced activity. Twelve fractions were chromatographically separated from the methanol phase, and electroantennography (EAG) analysis revealed that fraction 4 induced strong EAG responses in both winged and wingless aphids. Further identification of active compounds in fraction 4 by gas chromatography–mass spectrometry (GC–MS) indicated the presence of terpenes, aromatics, alkanes, esters, and phenols as major constituents. Subsequent EAG analysis identified several key compounds—octahydro-pentalene (C1), (Z)-cyclooctene (C2), dimethylstyrene (C3), tetramethyl-heptadecane (C5), tetrahydro-naphthalene (C6), and heptacosane (C9)—as responsible for eliciting EAG responses in both aphid forms. Additionally, results from Y-tube olfactometer assays showed that (Z)-cyclooctene and heptacosane were significantly attractive, while octahydro-pentalene acted as a strong repellent to both winged and wingless aphids. These findings offer valuable insights for the development of synthetic attractants and repellents for A. gossypii and provide a theoretical foundation for utilizing ginger in the creation of botanical pesticides targeting this pest. Full article

The potato tuber moth, Phthorimaea operculella (Zeller), is an important pest of potato crops capable of boring into and consuming the potato tubers. Although chemical insecticides are employed to control P. operculella populations, their efficacy is frequently limited, raising environmental concerns. Host plant volatiles are important allelochemicals that can be exploited for the management of pests. In our previous studies, we identified five volatile organic compounds (3-ethylacetophenone, 4-ethylacetophenone, geranylacetone, ethylbenzene, and 4-hydroxy-4-methyl-2-pentanone) as allelochemicals potentially influencing the oviposition behavior of P. operculella. Using electroantennography (EAG) and behavioral assays, we found that 4-ethylacetophenone significantly repelled P. operculella at all tested concentrations (1 μg, 10 μg, and 100 μg; p < 0.05), while 3-ethylacetophenone showed no significant effects (p > 0.05). Finally, the effect of 4-ethylacetophenone on preventing P. operculella from laying eggs was determined by an oviposition selection experiment. Our findings indicate that 4-ethylacetophenone derived from potato plants not only repels P. operculella and prevents egg-laying but also has the potential to reduce the number of eggs, making it a promising green alternative for controlling this pest. Full article

Olfaction mediated by the antennae is a vital sensory modality for arthropods and could be applied as a tool in pest control. The ectoparasitic mite Varroa destructor poses a significant threat to the health of the honey bee Apis mellifera worldwide and has garnered global attention. To better understand the chemical ecology of this host–parasite relationship, we collected and characterized the volatile organic compounds (VOCs) from V. destructor and used electroantennography (EAG) to record the responses of honey bee (A. c. cerana and A. m. ligustica) antennae to the different VOCs. Fifteen VOCs were detected from V. destructor using gas chromatography–mass spectrometry (GC-MS), which mainly contained ethyl palmitate, followed by isoamyl alcohol, nonanal, and ethyl oleate. The EAGs for ethyl palmitate were higher at the lowest stimulus loading (5 μg/μL in liquid paraffin) in A. c. cerana compared to A. m. ligustica, suggesting that A. c. cerana may have acute sensitivity to low concentrations of some VOCs from V. destructor. After exposure to ethyl palmitate for 1 h, the relative expression levels of AcerCSP1 and AcerOBP21 in A. c. cerana significantly increased, as well as the level of AmelCSP1 in A. m. ligustica, while AmelOBP8 showed no significant changes. The results indicate that the EAG response was influenced by the VOC composition and concentration. A. c. cerana tended to be more responsive than A. m. ligustica to the VOCs of V. destructor. Our findings offer a deeper understanding of how bees recognize V. destructor, potentially using ethyl palmitate as a chemical cue. Full article

Insects have highly developed olfactory systems in which cytochrome P450s (CYPs) were involved as odor-degrading enzymes throughout the olfactory recognition of odor compounds by insects to avoid continuous stimulation of signaling molecules and thus damage to the olfactory nervous. To understand whether the highly expressed CYPs in the antennae play an olfactory function in Solenopsis invicta worker, in this study, we find six highly expressed antennal CYPs from the transcriptome of S. invicta. Multiple sequence alignment and phylogenetic analysis divided them into two families: the CYP3 family (SinvCYP6K1, SinvCYP6K1-1) and the CYP4 family (SinvCYP4C1, SinvCYP4C1-1, SinvCYP4C1-2, SinvCYP4V2). The expression patterns of these six CYPs were analyzed by RT-qPCR, which revealed that SinvCYP6K1 and SinvCYP4V2 were only highly expressed in the antennae of adult workers. The expression of SinvCYP6K1 and SinvCYP4V2 in workers was markedly diminished after feeding with dsRNA. The electroantennography (EAG) assay demonstrated that the silencing of either SinvCYP6K1 or SinvCYP4V2 resulted in a notable reduction in the EAG response of workers to 2-ethyl-3,6(5)-dimethylpyrazine (EDMP). Furthermore, the trajectory behavior assay showed that the worker’s range and speed of movement in response to EDMP significant decreased after the silencing of SinvCYP6K1 and SinvCYP4V2. The findings indicated that both SinvCYP6K1 and SinvCYP4V2 were implicated in the recognition of EDMP by S. invicta. Full article

The poplar bark beetle Trypophloeus binodulus (Coleoptera: Scolytidae) is a key pest of poplar trees (Malpighiales: Salicaceae, genus Populus) across northern Spain. However, among the more than 200 poplar clones available on the market, the clone USA 184-411 has the highest susceptibility to T. binodulus attacks. We tested the hypothesis that compounds released by the most susceptible poplar clone chemically mediate Trypophloeus binodulus behavior. The leaf and bark volatile chemical profile composition of host poplar Populus nigra L. (Salicaceae) clones were analyzed and tested on adult T. binodulus by electroantennography (EAG) and by monitoring their populations in baited traps in northern Spain. The collection of volatiles released by the leaves and bark of both clones by SPME revealed the emission of 53 components from different chemical classes. Salicylaldehyde dominated these collections of leaf volatiles and was more abundant in aerations of the more susceptible poplar clone (USA 184-411). The EAG response of adult beetles to salicylaldehyde was higher than that of any other plant odorants. In field trials, traps baited with salicylaldehyde + ethanol significantly captured more adults than all other treatments, irrespective of other lure components. The present study could aid in developing semiochemical-based management tactics against this important pest. Full article

The fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) (FAW), is an invasive and destructive polyphagous pest that poses a significant threat to global agricultural production. The FAW mainly damages maize, with a particular preference for V3–V5 (third to fifth leaf collar) plant stages in northern China. How the FAW moth precisely locates maize plants in the V3–V5 stage at night remains unclear. The aims of this study were to evaluate the visual and olfactory cues used by the FAW to identify its host plant, maize, in order to select attractants with better trapping efficacy. Hyperspectral analysis of maize plants at different growth stages using the ASD Fieldspec 4 spectrometer was performed using mimics (moths or maize leaves sealed with transparent plastic sheets) and black cloth-covered plants for single visual and single olfactory attraction experiments. Gas chromatography–mass spectrometry (GC-MS) was used to analyze volatiles emitted from V3–V5 stage maize leaves. Volatile organic chemicals (VOCs) were screened using electroantennography (EAG) and Y-tube. Attractor efficacy was validated using mimics + VOCs. Results showed very little variance in the spectral reflectance curve of the maize at different growth stages. Fifteen VOCs were identified in the V3–V5 stage leaves of three different maize varieties, of which cis-3-hexenyl acetate and myrcene were found in relatively high concentrations in these maize varieties. The frequency of visits attracted by single visual stimuli was significantly lower than that attracted by single olfactory or olfactory + visual cues. The attractiveness of foliar cis-3-hexenyl acetate increased as its concentration decreased. The combination of mimics + cis-3-hexenyl acetate (1 ng/μL) increased host detection efficiency and stimulated mating behavior. These results indicate that the nocturnal insect FAW primarily uses olfactory cues for host identification, with visual cues serving as a complementary modality. The synergistic effect of olfactory and visual cues increases the efficiency of host recognition. We found that cis-3-hexenol acetate at a concentration from maize leaves is a reliable olfactory signal for the FAW. When using host plant VOCs as attractants to control adult FAWs, the role of visual cues must be considered. Full article