Volatiles from soybean flowers attract the Mexican soybean weevil, Rhyssomatus nigerrimus (Coleoptera: Curculionidae)

Abstract

The Mexican soybean weevil, Rhyssomatus nigerrimus Fahraeus (Coleoptera: Curculionidae), is a pest of soybeans. In this study we evaluate the volatiles of the soybean flower of the varieties FT-Cristalina-RCH and Flores as possible attractants for R. nigerrimus. Behavioral bioassays using an “Y” tube olfactometer and Electroantennography tests were performed to evaluate the responses of R. nigerrimus to the soybean flowers and their volatile extracts, in addition the volatiles were collected by dynamic aeration and identified using gas chromatography coupled with mass spectrometry (GC–MS). Bioassays showed that females and males were attracted by the flowers and volatile extracts of flowers of both varieties. However, females exhibited stronger antennal response than males to the volatile extracts of flowers of both varieties and their synthetic blends. The volatile extracts analysis showed the presence of 1-octen-3-one, 2-ethyl-1-hexanol, limonene, α-copaene, α-pinene, undecane, nonanal, octyl hexanoate, trans-α-bergamotene and calamanene. Quantitative differences in 1-octen-3-one, 2-ethyl-1-hexanol, α-pinene and limonene between the varieties were observed. In bioassays, males and females were attracted by α-copaene, 1-octen-3-ol α-pinene, and both synthetic blends. Females exhibited stronger antennal response than males to the synthetic compounds α-pinene, α-copaene, 1-octen-3-ol, nonanal and limonene.