|ROH, GWANG - Oak Ridge Institute For Science And Education (ORISE)|
|PARK, CHUNG - Gyeongsang National University|
Submitted to: Journal of Asia-Pacific Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/7/2021
Publication Date: 1/18/2021
Citation: Roh, G.H., Cha, D.H., Park, C.G. 2021. Olfactory attraction to aggregation pheromone is mediated by disti-flagellum of antennal segments in Riptortus pedestris. Journal of Asia-Pacific Entomology. 24(1):415-420. https://doi.org/10.1016/j.aspen.2021.01.005.
Interpretive Summary: Riptortus pedestris (bean bug) is a serious pest of soybean and sweet persimmon. It uses male produced aggregation pheromone to facilitate the colonization of host plants by conspecific adults and nymphs. It is currently unknown which part of their antennae is responsible for the detection of the pheromone. Researchers at USDA-ARS in Hilo, Hawaii and Gyeongsang National University in South Korea used anatomical, electrophysiological, and behavioral techniques to determine which antennal segment is responsible for the pheromone detection. Scanning electron microscopy revealed four antennal segments, and electroantennogram on each antennal segment showed that only the olfactory sensilla located in most distal antenna segment (disti-flagellum) could respond to the pheromone. In field trapping experiment, surgical removal of one disti-flagellum or both disti-flagella negated bean bug attraction to their aggregation pheromone, indicating that the disti flagellum houses olfactory neurons associated with the attraction to the pheromone.
Technical Abstract: Riptortus pedestris (Hemiptera: Alydidae) is a serious pest of soybean and sweet persimmon and uses male produced aggregation pheromone, (E)-2-hexenyl (Z)-3-hexenoate (EZ), (E)-2-hexenyl (E)-2-hexenoate (EE), and tetradecyl isobutyrate (TI) to facilitate food location and recognition by conspecifics. Using scanning electron microscopy (SEM), electroantennogram (EAG), and greenhouse bioassay, we determined which antennal segment is responsible for the detection of their aggregation pheromone. Using SEM, we identified four antennal segments (scape, pedicel, basi-flagellum, and disti-flagellum) from the filiform antennae of R. pedestris. Significant EAG responses to 1:1:1 mixture of the aggregation pheromone components were observed from the disti-flagellum segment of both male and female antennae when tested at two doses (1 µg and 100 µg). No EAG responses were observed from other antennal segments. In greenhouse experiment, removing one or both segment(s) of disti-flagellum from male or female antennae resulted in significant reduction in their attraction to the aggregation pheromone, suggesting that the disti-flagellum houses olfactory neurons associated with the attraction to the pheromone.