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

Abstract

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.

Keywords:

• attraction range
• cucurbitacins
• pest Chrysomelidae
• vane trap

Acknowledgements

We wish to thank the Cabrera Walsh family for allowing us to perform the experiments in their fields; and the late Javier Jara for assistance in the field. Also, we thank Corey Gerber (Purdue University, Indiana) and Jonathan Lundgren (USDA/ARS/NCARL, South Dakota) for helpful critical reviews of a previous version of the manuscript.