Studies on chemical ecology of the heteropteran scent gland components

Abstract

Heteropterans, or true bug, produce foul-smelling odors commonly composed of α,β-unsaturated aldehydes and their derivatives such as 4-oxo-(E)-2-hexenal that play important roles in chemical defense and communication. However, the defensive roles of each scent gland components are not well understood. In this study, repellent, feeding deterrent, toxic and antimicrobial effects of each scent gland component were evaluated using chemical identification and behavioral assays. (E)-2-Hexenal and (E)-2-octenal showed repellent activities against insect predators. (E)-2-Octenal also functioned as feeding deterrent agaist the predators. Our predator behavioral assays revealed that OHE was deterrent and toxic but not repellent against the predators. This compound also induced permanent locomotive impairment in crickets that correlates with free thiol depletion. All of the α,β-unsaturated aldehydes showed antimicrobial activities. Having diverse defensive components that function differently in a blend could fortify the heteropteran chemical defense system.