Influence of temperature and humidity on survival, development period and adult sex ratio in Prostephanus truncatus (Horn) (Coleoptera, Bostrichidae)

Abstract

Prostephanus truncatus (Horn) is an established pest of maize in Central America. but has been only rarely recorded from elsewhere. Development from hatching to adult was possible at every one of the 24 combinations of 6 temperatures and 4 relative humidities used. and the period required was shortest at 32°C 80% r.h. Rate of development was obviously slower at 35°C than 32°C, being similar to that observed for 25–27°C. At 22°C the rate of development was appreciably slower. Below 70% r.h. at all temperatures the developmental period increased markedly, but at 80% r.h. it was sometimes shorter and sometimes longer than at 70%. In general, mortality was low in the 27–32°C, 70–80% r.h. zone, but tended to increase at lower humidities and more extreme temperatures, especially 35°C. A developmental index combining both rate of development and mortality confirmed 32°C 80% r.h. as optimal. There was no evidence that the physical environment affected the sex ratio of emerging adults.