Semiochemical bait control and behavior of the western corn rootworm Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae)
Abstract
During 1990, Nemesis CRW, an insecticide semiochemical bait was tested in five fields in Indiana for efficacy in controlling corn rootworm adults. Fields were divided into untreated (approximately 15 ha) and treated (bait broadcast by plane over 15 ha) areas. The bait caused a quick knock-down of the population as confirmed by counts of dead beetles on the ground. Beetles caught on sticky traps showed that population density of western corn rootworm recovered to previous levels eight days after application. Use of the bait did not affect the beetle densities during next year. During 1991 and 1992, sticky traps were studied as monitoring devices for western corn rootworm adults. Traps were located in three sections of the plant: top, center, and bottom. The first year more beetles were caught on the center trap than top and bottom, and the following year more catches were at the bottom part of the crop canopy. More males were caught than females. Swarming behavior of corn rootworm male beetles was described. This is an excited movement of 20-50 males in a small area and was detected while observing behaviors of the beetles in the field. Other types of beetle behaviors observed in the field included feeding, grooming, resting, walking, flying, pairing, copula, searching for oviposition site, fleeing, and aggression. As a result of the close observation of the beetles mating behavior, a sexually dimorphic character was identified in males of western corn rootworms, D. v. virgifera, northern corn rootworms, D. barberi, and the spotted cucumber beetles, D. undecimpunctata howardi. The character, disco-setae, is found in the basitarsi of the foreleg, and the basitarsi of the midleg. Disco-setae help the males grasp the elytra of the female during pairing and mating.
Degree
Ph.D.
Advisors
Turpin, Purdue University.
Subject Area
Entomology|Ecology
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