Effects of Temperature and Relative Humidity on Egg Development of Cryptolestes ferrugineus Compared with C. pusillus : Coleoptera

Development and mortality of eggs of a stored-grain pest in Canada, the rusty grain beetle, Cryptolestes ferrugineus (STEPHENS) (Coleoptera : Cucujidae), were observed at 15 to 35°C and 50 to 90% relative humidity (RH). At 15°C no eggs hatched. Mortality was higher at 15 and 19°C than at 25, 30 and 32°C. The developmental rate (1/day), D, was expressed by a linear regression function of temperature, T; D=0.0169T-0.258. Mortality and developmental rate was unaffeted by the relative humidity. Eggs of C.ferrugineus were more tolerant to high temperatures and low relative humidities than eggs of the flat grain beetle, Crytolestes pusillus (SCHONHERR), a closely related pest.