Effect of constant temperature and humidity on oviposition and development of Callosobruchus maculatus (F.) and Callosobruchus subinnotatus (Pic) on bambara groundnut, Vigna subterranea (L.) Verdcourt

Abstract

The effect of different conditions of temperature and humidity on oviposition and development of Callosobruchus maculatus and Callosobruchus s ubinnotatus was investigated in the present study. Four temperatures (25°C, 30°C, 35°C and 40°C) and three humidities (30%, 60% and 90% r.h.) were evaluated on both species in pure and mixed populations on bambara groundnut ( Vigna subterranea) seeds. In both pure and mixed populations, temperature influenced oviposition and progeny development of both species significantly more than humidity. Egg-laying and progeny development in C. maculatus were optimal at 35°C. In contrast, oviposition and progeny development in C. subinnotatus were optimal at 30°C. In mixed populations, where eggs were laid by females of C. maculatus and C. subinnotatus held together, more C. maculatus adults than C. subinnotatus adults were produced at the various temperatures and humidities. No adult progeny of either species developed in pure or mixed populations at 40°C. C. maculatus was more fecund than C. subinnotatus and development from egg to adult took much longer in C. subinnotatus than in C. maculatus in both pure and mixed populations. The implications of these findings for the development and survival of both species in the different agroecologies and seasons in Nigeria are discussed.