A supplemental component of aggregation attractant pheromone in the bean bug Riptortus clavatus (Thunberg) (Heteroptera: Alydidae), related to food exploitation

Abstract

Traps baited with dried soybeans and a synthetic aggregation attractant pheromone were more effective than traps baited with synthetic aggregation pheromone alone against the bean bug, Riptortus clavatus. Dried soybeans alone did not attract bean bugs, so this difference was not due to the attractiveness of the dried soybean itself. The known components of the aggregation pheromone were detectable only in extracts of a few individual attracted bugs; however, all the attracted male bugs had (E)-2-hexenyl hexanoate, which has been identified as an alarm pheromone in this species. This component was present in higher amounts in extracts of male or female R. clavatus that had been fed on soybeans than that of starved males or females. In the experiments, the attractiveness of tetradecyl isobutyrate, which is an essential component of aggregation pheromone, was increased by the addition of (E)-2-hexenyl hexanoate. These results suggested that (E)-2-hexenyl hexanoate is one of the components of the attractant aggregation pheromone of R. clavatus and that it may act as a synergistic composition but not a repellent. It is hypothesized that the pheromonal process related to food exploitation in R. clavatus includes positive feedback since attracted bugs stay to feed at sites and continuously release (E)-2-hexenyl hexanoate.