|Cabrera Walsh, Guillermo - Fuedei|
|Mattioli, Federico - Fuedei|
Submitted to: Journal of Pest Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/20/2014
Publication Date: 7/31/2014
Publication URL: http://handle.nal.usda.gov/10113/60170
Citation: Cabrera Walsh, G., Mattioli, F., Weber, D.C. 2014. Differential response of male and female Diabrotica speciosa (coleoptera: chrysomelidae) to bitter cucurbit-based toxic baits in relation to the treated area size. Journal of Pest Science. 60(2):128-135.
Interpretive Summary: Cucumber beetles and corn rootworms, key pests of maize and vegetables in North and South America, are attracted in large numbers to juices of cucurbits (squash, melons and gourds) rich in bitter natural chemicals called cucurbitacins. Because they are attracted to and consume cucurbitacins, the leaf beetle pest populations can potentially be suppressed with these selective baits which contain greatly reduced amounts of pesticide, and thus exert little or no effect on beneficial insects. However, field trials reveal that males are far more attracted than females, which could mean that baits, depending on application method and pest response, will not effectively 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 suppression (mortality) of South American corn rootworm adult beetles by cucurbitacin-based baits applied in sprays to different-sized plots of crops in Argentina. The small area bait applications attracted mostly males (over 95%), but the 1-ha (2.2-acre) treated plot showed a near-equal mortality of males and females (57% male). The research results suggest that treatment of whole fields, rather than limited areas or point sources such as traps or trap plants, will be optimal in suppressing pest populations of rootworm adult beetles, including females which are not attracted from a distance. No significant non-target effects were observed. This information will be useful to researchers and pest managers addressing environmentally-friendly management of corn rootworms and cucumber beetles in South and North America.
Technical Abstract: Cucurbitacins are fed on by male and female Luperini but field trials reveal that males are far more attracted to them than females. The sex ratio and number of beetles killed by an application of cucurbitacin based toxic baits was assessed at two different scales: small areas of 100 m2, and a larger area of 10,000 m2. The small area bait applications attracted mostly males (95.2%), but the 1-ha treated plot showed a lower sexual bias (57% male). An earlier study indicated point sources (traps) attracted only males. The distance attraction to cucurbitacins is almost exclusive to males, but the fine dispersal of a bait should promote encounter and control of both sexes within the treated area. No significant non-target effects were observed.