Influence of the presence of flour on the efficacy of low temperatures against stored product insects

Abstract

The efficacy of low temperatures ranging from 0 to −15 °C was evaluated against all life stages of Tribolium confusum, adults of Oryzaephilus surinamensis and adults of Liposcelis bostrychophila. All species/life stages were exposed in empty vials or vials containing 5 g of flour, for time intervals of 2–7 d. Eggs and pupae were the least susceptible life stages of T. confusum, as these life stages had the highest survival at – 15 °C. Nevertheless, at this temperature, an exposure of 4 and 8 h for eggs and pupae, respectively, resulted in no survival. In most combinations, the presence of flour did not affect survival of T. confusum exposed to any temperature. There was no survival of O. surinamensis adults after exposure to −5 °C for 7 d or to −10 °C for 8 h, and the presence of flour had no effect on survival. Adults of L. bostrychophila were the most-cold tolerant among the species and life stages tested; at −10 °C, mortality was 100% only after 7 d of exposure. For this species, the presence of flour had some effect on adult survival, but results were not consistent with temperature. The results of this study can be utilized to develop control programs for using low temperatures as a disinfestation strategy for infested commodities.