A multicomponent marking phermone produced by the PEPPER WEEVIL, Anthonomus eugeni (Coleoptera: Curculionidae).

Authors: ADDESSO, K - Tennessee State University; Alborn, Hans; Bruton, Robert; MCAUSLANE, H - University Of Florida

Submitted to: Chemoecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/22/2021
Publication Date: 4/8/2021
Citation: Addesso, K.M.; Alborn, H.T.; Bruton, R.G.; Mcauslane, H.J. 2021. A multicomponent marking phermone produced by the PEPPER WEEVIL, Anthonomus eugeni (Coleoptera: Curculionidae). Chemoecology 31:247-258. 2021. https://doi.org/10.1007/s00049-021-00347-3.
DOI: https://doi.org/10.1007/s00049-021-00347-3

Interpretive Summary: The pepper weevil is a major pest of cultivated pepper throughout the southern United States, Mexico and the Caribbean. The weevil chews a cavity in a fruit or flower where she deposit one egg and cover the oviposition site by a plug derived from anal secretions. The larvae feed on the developing seeds and placental material, resulting in infested peppers to fall to the soil surface, reducing yield dramatically. Detection of infested harvested fruits results in rejection of entire shipments. Female weevils tend to avoid fruit that other female weevils previously layed eggs on (oviposit) and scientists at USDA-ARS Center for Medical, Agricultural, and Veterinary Entomology, Gainesville FL, in collaboration with colleagues at Tennessee State University and University of Florida, found that an oviposition deterring pheromone was present in the plug. Investigations of the plugs identified several free fatty acids as major constituents but causing only a slight reduction in oviposition when applied to pepper fruit. Utilizing in-house developed techniques, volatiles were collected and identified from individual plugs of which only the chemical compound acetophenone elicited a behavioral response by the female weevil in lab-based bioassays. When pepper fruits were treated with a combination of acetophenone and a plug mimicking blend of unsaturated fatty acids, oviposition on treated peppers was found to decrease by up to 75%. We propose the identified pheromone, comprised by a combination of volatile and contact acting components, improves oviposition site selection efficiency by pepper weevils on discrete hosts. It might be possible to utilize this knowledge in integrated pest management strategies to control this pest and the discovery of an unusual type of pheromone can guide the identification of similar pheromones produced by other Anthonomus pest weevils.

Technical Abstract: nsects in several orders deposit marking pheromones following oviposition which signal the presence of eggs to subsequent females. This form of chemical communication is particularly prevalent in species which oviposit on discrete hosts with limited resources available for developing larvae. The pepper weevil is a major pest of cultivated pepper throughout the southern United States, Mexico and the Caribbean. The weevil deposits eggs singly in a cavity chewed in flower buds and small fruits and caps these cavities with a plug derived from an anal secretion. The deterrent was found to be located in this oviposition plug and comprised of volatile and contact-acting components. Plug volatiles were collected by inducing oviposition into Teflon tape sachets containing pepper leaves and collecting volatiles from plugs laid on the tape surface. Of the two major components observed by GC/MS analyses, only acetophenone elicited a behavioral response by the female weevil in small arena and wind tunnel assays. Investigations of the oviposition plug matrix identified several free unsaturated and saturated fatty acids as major constituents of the plug which was in stark contrast to pepper tissue and seeds that contained only trace levels of free fatty acids and a distinctly different total fatty acid composition. The combined free fatty acids well as acetophenone tested singly gave no significant reduction in oviposition while a plug-mimicking blend of unsaturated fatty acids tested in combination with acetophenone as artificial ‘plug spots,’ decreased oviposition on treated peppers by up to 75%. We propose that the combination of volatile and contact acting marking components improves oviposition site selection efficiency by pepper weevils on discrete hosts.