The effects of short exposures to subthreshold temperatures on subsequent hatching and development of eggs of Tribolium confusum Duval (Coleoptera, Tenebrionidae)

Abstract

Tribolium confusum eggs of different ages at 28°C were exposed at 5 or 10°C for 1, 5, 10 or 15 days and then kept at 22 or 28°C and observed for hatching and periods of development. Eggs, 1–2 hr and 3–4 hr old, were more susceptible to injury at 5 and 10°C than eggs 1, 3 and 4 days old. Although 3- and 4-day-old eggs hatched after low temperature exposures of 10 and 15 days, larval mortality was high. The egg stage was generally prolonged only by the time spent at 5 or 10°C. With a few exceptions there was no overall retardation or acceleration of the postembryonic period caused by egg exposures at 5 or 10°C for 1, 5 or 10 days. There was evidence that individuals obtained from eggs exposed at 10°C for 1 day laid more eggs at 28°C than the controls. The results suggest that storage of flour at 5 or 10°C for 15 days will kill T. confusum eggs that may be present near the periphery of sacks.