A wind-oriented sticky trap for evaluating the behavioural response of the leaf-beetle Diabrotica speciosa to cucurbit extracts

Cucurbitacins are plant defensive chemicals that attract many species of adapted insect herbivores such as luperine leaf beetles, and they have been employed in traps and toxic baits. Male and female beetles feed avidly on baits containing these compounds, but field trials have revealed that males find them far more attractive than females. A wind-oriented baited sticky trap was designed to evaluate the response of Diabrotica speciosa to cucurbit extracts, by means of a mark–release–recapture experiment. The spatial range of attraction was less than 20 m, and captures were almost exclusively of males (99.91%). Distance attraction for D. speciosa to a point-source of bitter cucurbit juices is probably exclusive to males. These conclusions probably apply to most Diabrotica species, of which many are crop pests.