|Cabrera Walsh, Guilermo|
Submitted to: International Journal of Pest Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/2/2014
Publication Date: 5/28/2014
Publication URL: http://handle.nal.usda.gov/10113/60171
Citation: Cabrera Walsh, G., Mattioli, F., Weber, D.C. 2014. A wind-oriented sticky trap for evaluating the behavioural response of diabrotica speciosa (germar) to bitter cucurbit extracts. International Journal of Pest Management. 60:46-51. Interpretive Summary: Cucumber beetles and corn rootworms are serious pests of maize and vegetables in North and South America. Juices of cucurbits (squash, melons and gourds) rich in bitter natural chemicals called cucurbitacins attract large numbers of these leaf beetles. Because they are attracted to and consume cucurbitacins, pest populations can potentially be suppressed with selective traps and/or baits which reduce pesticide applications and effects on beneficial insects. However, field trials reveal that males are far more attracted than females, which could mean that traps or baits will not effectively monitor and suppress females, which will then still be capable of laying enough eggs for the larvae to cause heavy damage in the roots of maize and other crops. In this work, we assessed the captures of South American corn rootworms on cucurbitacin-baited sticky traps which showed the direction from which beetles flew to the trap. Beetles always approached the trap from downwind, indicating their attraction to the volatile odors of the cucurbitacin-containing plant extracts used. Of over 2000 beetles trapped, only 2 were females, in spite of the presence of numerous females in the crops nearby. The attraction range of a point source of cucurbitacin is quite short (~20 meters), and exclusively limited to males. This means that traps will be of no use in monitoring or suppressing females, but rather, that finely-dispersed baits will be preferable in pest management, since females need not be attracted to them to encounter and consume the baits. This information will be useful to researchers and pest managers addressing environmentally-friendly management of corn rootworms and cucumber beetles.
Technical Abstract: Cucurbitacins attract many species of Luperini leaf beetles, for which they have been studied and applied in traps and toxic baits. Males and females feed avidly on these compounds, but field trials reveal that males are far more attracted to them 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 range of attraction was under 20 m, and captures were almost exclusively males (99.91%). Distance attraction for D. speciosa to a point source of bitter cucurbit juices is probably exclusive to males. These conclusions could probably be extended to most Diabrotica species.