Attraction of adultDiabrotica (Coleoptera: Chrysomelidae) to corn silks and analysis of the host-finding response.

Volatile chemicals from corn silks attractedDiabrotica virgifera virgifera LeConte andD. barberi (Smith and Lawrence). The behavioral response of both species of beetles to the host plant was typified by four distinct phases: perception, random movement, orientation to the source, and search with reorientation. The perception phase was composed of stationary behaviors, while the random, orientation, and search phases were composed of directed and nondirected movements. Each of the movement phases had a characteristic response pattern composed of the ratio of upwind, lateral, and downwind walking and flight movements, which affected net displacement of the beetle in the flight tunnel. The perception phase occurred within and between the other phases and was responsible for initiating changes from one movement phase to another (based on the presence or absence of volatiles from corn silks). Host finding was flexible, and the response pattern fit a flow-chart type of response, rather than a single stereotyped sequence of behaviors.