Search

Background: Helopeltis cinchonae (Hemiptera: Miridae) is a major pest of tea plantations in Asia. Conventional control of pests with pesticides is unsustainable. Therefore, safe and eco‐friendly alternatives, such as pheromones, are required to manage the pest. Results: In gas chromatography–electroantennographic detection (GC–EAD) analysis of whole‐body extracts of virgin female H. cinchonae, two compounds elicited electroantennogram (EAG) responses from male antennae. These were identified as hexyl (R)‐3‐acetoxybutyrate and (R)‐1‐acetoxy‐5‐butyroxyhexane using gas chromatography–mass spectrometry (GC–MS) analysis compared to synthetic compounds. This is the first study to report 1‐acetoxy‐5‐butyroxyhexane as an insect pheromone component. The synthetic compounds elicited dose‐dependent EAG responses from the antennae of male H. cinchonae. In two field trapping experiments, the individual compounds were highly attractive to male H. cinchonae when dispensed from polyethylene vials. However, higher catches were obtained with blends of the two compounds in a 1:10 ratio. The blend of racemic compounds was as attractive as the blend of (R)‐enantiomers. Conclusions: We reported that 1‐acetoxy‐5‐butyroxyhexane and hexyl 3‐acetoxybutyrate are components of the female‐produced sex pheromone of H. cinchonae, but further work is required on the blend and loading of pheromone and on trap design to provide an optimized system for monitoring and control of this pest. The results may also facilitate the identification of the pheromones of other Helopeltis species, which are major pests in many crops. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: The stick tea thrips, Dendrothrips minowai Priesner, is one of the most important sucking pests that seriously infest tea plants (Camellia sinensis) in China. Given that D. minowai exhibit aggregation behaviors in tea plantations, this study evaluated the potential of aggregation pheromones for their control. RESULTS: H‐tube olfactometer assays showed that D. minowai larvae, adult females and adult males were significantly attracted to larvae rather than adult females and males under laboratory conditions. Subsequent gas chromatography–mass spectrometry analysis of volatiles from larvae, identified two larva‐specific components: dodecyl acetate and tetradecyl acetate. Electrophysiological and behavioral experiments confirmed the positive response of females and males to dodecyl acetate, tetradecyl acetate, and their blend (1:1.5). Deployment of these aggregation pheromones on sticky traps resulted in a 1.2‐ to 3.0‐fold increase in the capture of D. minowai adults compared with control traps. In addition, deployment of sticky traps baited with these aggregation pheromones within tea plantations resulted in a noteworthy reduction in the population of adult thrips per 100 leaves, 10 days following trap deployment. The reduction ranged from 29% to 59%, in comparison with the control. CONCLUSION: D. minowai larvae produce aggregation pheromones, dodecyl acetate and tetradecyl acetate, that can be useful for controlling tea thrips. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Empoasca onukii Matsuda (Hemiptera: Cicadellidae) is the primary pest of tea gardens, but the species' sexual communication and mating behavior is currently unclear. A similar species, Empoasca vitis Göthe, had been reported to use vibrational signals for mating communication, so we studied these two aspects from the perspective of biotremology. First, laser vibrometry detected both males and females could emit vibrational signals that are sex specific. Females emitted one signal type (the female signal), and males emitted two signal types: the male calling signal and the male courtship signal. Compared with the male signals, the female signal has a simpler structure, lower dominant frequency, and shorter length. Second, the vibrational signals of E. onukii play a decisive role in sexual communication. The male emits calling signals and then recognizes the female based on her reply signal; after establishing a duet with the female, the male emits a series of courtship signals, and then continually locates and approaches the female according to her reply signals, and finally attempts to copulate. Third, vibrational signals of E. onukii are species‐specific. Comparing E. onukii and E. vitis, there are differences in three aspects: the emitting behavior of female signals, the types of male signals, and the structure of male and female signals. We conclude that E. onukii uses sex‐ and species‐specific vibrational signals for sexual communication. [ABSTRACT FROM AUTHOR]

BACKGROUND: The tea black tussock moth Dasychira baibarana Matsumura is a devastating pest in tea plantations that causes substantial economic losses. Presently, there is no effective method to control this pest other than pesticide application. The identified sex pheromone of D. baibarana could be used for detecting and monitoring this pest. RESULTS: Gas chromatography–electroantennogram detection showed that D. baibarana male moth antennae responded strongly to three components in the female sex pheromone gland, which were identified as: (3Z,6Z)‐cis‐9,10‐epoxyhenicosa‐3,6‐diene (Z3,Z6,epo9‐21:H) (I), (3Z,6Z,11E)‐cis‐9,10‐epoxyhenicosa‐3,6,11‐triene (Z3,Z6,epo9,E11‐21:H) (II) and (3Z,6Z)‐henicosa‐3,6‐dien‐11‐one (Z3,Z6‐21:11‐one) (III). Dasychira baibarana uses a unique composition of an epoxydiene, epoxytriene, and dienone with the same 3,6‐dienyl motif as its sex pheromone. The epoxytriene and dienone were not previously characterized as insect pheromone components. Electroantennogram analysis showed that each synthetic compound strongly stimulated male antennae, and compounds II and III elicited stronger responses than compound I. A wind tunnel bioassay and field trapping experiments proved that, ternary blends of compounds I–III attracted D. baibarana. Efficient attraction was achieved with a rubber septum baited with 500 μg of a mixture of compounds I–III at the ratio 25:20:55. CONCLUSION: The three identified compounds elicited an electroantennogram response in D. baibarana male moth antennae, and a mixture of the three components at the ratio 25:20:55 attracted D. baibarana male moths in a wind tunnel assay and field trapping experiments. This blend could be used for integrated management of D. baibarana in tea plantations. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Chrysomelina beetlesstore 3‐nitropropionic acid in form of a pretoxin, isoxazolin‐5‐one glucoside‐conjugated ester, to protect themselves against predators. Here we identified a cytochrome P450 monooxygenase, CYP347W1, to be involved in the production of the 3‐nitropropionic acid moiety of the isoxazolin‐5‐one glucoside ester. Knocking down CYP347W1 led to a significant depletion in the concentration of the isoxazolin‐5‐one glucoside ester and an increase in the concentration of the isoxazolin‐5‐one glucoside in the larval hemolymph. Enzyme assays with the heterologously expressed CYP347W1 showed free β‐alanine was not the direct substrate. Homology modeling indicated that β‐alanine‐CoA ester can fit into CYP347W1's active site. Furthermore, we proved that Phaedon cochleariae eggs are not able to de novo synthesize 3‐NPA, although both isoxazolin‐5‐one glucoside and its 3‐NPA‐conjugated ester are present in the eggs. These results provide direct evidence for the involvement of CYP347W1 in the biosynthesis of a P. cochleariae chemical defense compound. [ABSTRACT FROM AUTHOR]