A long-range attractant kairomone for egg parasitoid Trissolcus basalis, isolated from defensive secretion of its host, Nezara viridula
1993
A short-chain alpha,beta-unsaturated aldehyde, (E)-2-decenal, present in the defensive metathoracic gland of Nezara viridula (L.) (Heteroptera: Pentatomidae), stimulates a behavioral response in the egg parasitoid Trissolcus basalis (Woll.) (Hymenoptera: Scelionidae). Preliminary studies showed that T. basalis are attracted to an area containing adult N. viridula, but we also found that female T. basalis would examine and probe glass beads coated with an acetone extract of the metathoracic gland from males or females. Using this bioassay, the kairomone was isolated by bioassay directed by preparative gas chromatography and identified by NMR and mass spectrometry as (E)-2-decenal. The biological activity of the identified aldehyde was compared with analogs to determine specificity. An unstable Z isomer was found to be more active but not present in detectable or behaviorally relevant levels in the host, based on the bell-shaped dose-response curve of the two isomers. An investigation was also designed to determine if the E isomer was also responsible for the egg recognition kairomone activity previously reported. However, no 2-decenal isomers were detected in host egg extracts and the chemical characteristics of the 2-decenal isomers differ from the unidentified egg recognition kairomone. The role of the (E)-2-decenal in attracting female T. basalis to N. viridula was demonstrated in a Y-tube olfactometer; this alk-2-enal appears to act as a long-range kairomone orienting T. basalis to Nezara populations.
显示更多 [+] 显示较少 [-]