The influence of temperature and humidity on the biology of insecticide-resistant and susceptible strains of Tribolium castaneum (Herbst) was studied and compared.
At all temperatures (20, 25,30 and 40°C) and r.h. (30, 50,70, 90) tested, the insecticide-resistant strain matured earlier than the susceptible strain. For both strains, the lowest and highest temperature limits for embryonic development and egg hatching were 20 and 40°C, respectively. The incubation period for eggs of both strains averaged 14 days at 20°C and 4 days at 30°C.
Females of the insecticide-resistant strain matured for egg laying earlier (24 hr) than the susceptible strain (60 hr) but laid fewer eggs (36 eggs) than the latter strain (238 eggs). At 30°C and 70% r.h. the resistant strain had a shorter developmental period (15 days) than the susceptible strain (21 days).
Temperature influenced the development of larvae of both strains of T. castaneum. Larvae of the susceptible strain did not develop at 20°C and 30% r.h., 20°C and 90 % r.h. and 40°C and 30%. r.h., whereas larvae of the resistant strains did.
The pupae of both strains developed at all the temperature and relative humidity regimens tested. Temperature and humidity of stored food would therefore, act together to influence the abundance of strains of T. castaneum and the two factors could be manipulated to suppress the population growth of this beetle on stored food.