Electrophysiological and behavioral responses of Diaphania glauculalis males to female sex pheromone

Quantitative analysis and characterization of floral volatiles, and the role of active compounds on the behavior of Heortia vitessoides

This study explores the role of floral volatile organic compounds (FVOCs) in insect behavior, focusing on Aquilaria sinensis (AS), a valuable tropical plant threatened by Heortia vitessoides Moore. Despite H. vitessoides' attraction to AS and non-host plants like Elaeocarpus decipiens (ED) and Dalbergia odorifera (DO), little is known about their chemical interactions. FVOCs from these plants were analyzed at 9:00 and 18:00 using GC×GC-QTOF-MS and HS-SPME. The results showed that ED exhibiting the highest concentration (92.340 ng/mg), followed by DO (75.167 ng/mg) and AS (64.450 ng/mg). Through GC-EAD and EAG, a total of 11 FVOC compounds with electrophysiological activates were identified. These compounds, except linalool, showed dose-dependent responses. Y-Tube bioassays confirmed phenylethyl alcohol or the mixture of EAD-active compounds produced positive chemotactic responses in both males and females. FVOCs have the potential to be used as a natural and sustainable alternative to chemical insecticides in pest control.

Structure, Synthesis, and Bioassays of Sex Pheromone for Pyrausta machaeralis (Lepidoptera: Crambidae)

The leaf skeletonizer, Pyrausta machaeralis (Lepidoptera: Crambidae), is a serious insect pest of teak (Tectona grandis) in China. The application of insect pheromones is widely applied as an environmentally friendly technology for integrated pest management (IPM). In the present study, crude extracts of sex pheromone glands of calling P. machaeralis females were collected and then analyzed using gas chromatography/electroantennographic detection (GC/EAD) and gas chromatography-mass spectrometry (GC-MS). The combination of infrared spectroscopy (IR) and nuclear magnetic resonance (NMR) spectrometry was used for structure identification. Afterward, their electrophysiological and behavioral activity was evaluated in the laboratory and field. Herein, we eventually determined two active components, E-11-tetradecenyl acetate (E11-14:Ac) and Z-11-tetradecenyl acetate (Z11-14:Ac), at a ratio of 96:4, as the sex pheromone of P. machaeralis. The identification of sex pheromones would facilitate the development of efficient strategies for monitoring and controlling the field populations of P. machaeralis.

Characterization and Functional Analysis of OcomOBP7 in Ophraella communa Lesage

The olfactory system plays a key role in various insect behaviors, and odorant-binding proteins participate in the first step of the olfactory process. Ophraella communa Lesage is an oligophagous phytophagous insect that is a specific biological control agent for Ambrosia artemisiifolia L. The leaf beetle must identify and locate A. artemisiifolia through olfaction; however, its odorant-binding protein (OBP) function has not yet been reported. In this study, OcomOBP7 was cloned, and its tissue expression profile and binding ability were analyzed using RT-qPCR and fluorescence binding assays, respectively. Sequence analysis demonstrated that OcomOBP7 belongs to the classical OBP family. The RT-qPCR results showed that OcomOBP7 was specifically expressed in the antennae, indicating that OcomOBP7 may be involved in chemical communication. The fluorescence binding assay showed that OcomOBP7 has an extensive binding ability to alkenes. The electroantennography experiments showed that O. communa antennal response to α-pinene and ocimene decreased significantly after interference because the two odors specifically bound to OcomOBP7. In summary, α-pinene and ocimene are odorant ligands corresponding to OcomOBP7, indicating that OcomOBP7 is involved in the chemical recognition of A. artemisiifolia. Our study lays a theoretical foundation for research into O. communa attractants, which is helpful for the better biological control of A. artemisiifolia by O. communa.

Reverse chemical ecology guides the screening for Grapholita molesta pheromone synergists

BACKGROUND

Pheromone-based management is a leading nonpesticidal strategy among integrated pest management options. Improving the potency of pheromone products by adding synergists would be a practical way to popularize pheromone-based management as well as to reduce pesticide use.

RESULTS

Using reverse chemical ecology, synergists for Grapholita molesta sex pheromone were screened. Combined molecular docking and in vitro binding assay led to the determination of four potentially active odorants showing high affinity to G. molesta pheromone binding protein 2 (GmolPBP2). Thereafter, the high affinity between Codlemone and GmolPBP2 was further verified by exploration of GmolPBP2-Codlemone interactions. As the only sex pheromone synergist validated by both laboratory behavioral tests and field trapping, Codlemone was used to optimize commercial sex attractants currently used in G. molesta control. The recommended formulation [(Z)-8-dodecenyl acetate:(E)-8-dodecenyl acetate:Codlemone = 95:4:10] was found to trap about five to six times more G. molesta adults than the commercial sex attractant [(Z)-8-dodecenyl acetate:(E)-8-dodecenyl acetate: (Z)-8-dodecenol = 95:4:1].

CONCLUSION

Codlemone is an excellent pheromone synergist that can be potentially sensed by GmolPBP2, which can remarkably improve the potency of G. molesta sex attractants. It is believed that the introduction of reverse chemical ecology would increase the chance of discovering pheromone synergists, promoting the development of more efficacious pheromone products that can be used in controlling G. molesta and beyond. © 2021 Society of Chemical Industry.

Latest Developments in Insect Sex Pheromone Research and Its Application in Agricultural Pest Management

Since the first identification of the silkworm moth sex pheromone in 1959, significant research has been reported on identifying and unravelling the sex pheromone mechanisms of hundreds of insect species. In the past two decades, the number of research studies on new insect pheromones, pheromone biosynthesis, mode of action, peripheral olfactory and neural mechanisms, and their practical applications in Integrated Pest Management has increased dramatically. An interdisciplinary approach that uses the advances and new techniques in analytical chemistry, chemical ecology, neurophysiology, genetics, and evolutionary and molecular biology has helped us to better understand the pheromone perception mechanisms and its practical application in agricultural pest management. In this review, we present the most recent developments in pheromone research and its application in the past two decades.