Mortality of different developmental stages of Callosobruchus maculatus F.and Callosobruchus subinnotatus Pic. (Coleoptera : Bruchidae) in bambaragroundnut Vigna subterranea (L.) Verdc. seeds exposed to simulated solarheat

摘要

The susceptibility of Callosobruchus maculatus F. and Callosobruchus subinnotatus Pie. eggs, first and late instar larvae as well as adults to the lethal effect of solar heat of a temperature of 50 degreesC simulated in an incubator was evaluated. Development of adult progeny was completely suppressed in both species in bambara groundnut seeds bearing I-day-old eggs or harboring first instar lan ae exposed for 4 or 6 h to this temperature. Suppression of adult progeny development was due to the fact that this level of heat caused 100 % mortality of these developmental stages of the bruchids. In C. maculatus, 100 % mortality occurred in first instar larvae exposed for 2 h while in C. subinnotatus, 100% mortality occurred in eggs and first instar Larvae exposed for a similar duration. In addition, adults of both species that were exposed for 25 min, and in the case of C, maculatus adults exposed for 20 min as well, sustained 100 % mortality. On average, C. maculatus adults with a mortality figure of 50.7 % were more susceptible to the lethal effect of this level of heat than C. subinnotatus adults with a mortality figure of 37.0 %. Solar heat could be used as :Ln inexpensive method for control of these pest species in developing countries.