Efficacy of low temperatures for the control of all life stages of Plodia interpunctella and Liposcelis bostrychophila

The insecticidal effect of low temperatures for the control of all life stages of two stored-product insects, Plodia interpunctella and Liposcelis bostrychophila, was evaluated under laboratory conditions. The temperatures tested were 0, -5, -10 and -15 degrees C, and, at these temperatures, the insects were exposed for 2, 4 and 8 h and also for 1, 2, 3 and 7 days. Regarding P. interpunctella, the most cold-tolerant life stage was larvae, given that 2 days of exposure were needed for complete (100%) mortality at -10 degrees C. Moreover, all larvae were dead at -15 degrees C even after 2 h of exposure. Eggs of P. interpunctella were susceptible to cold, as mortality was complete after 7, 1 day, 2 and 2 h at 0, -5, -10 and -15 degrees C, respectively. L. bostrychophila was by far less susceptible than P. interpunctella. For this species, adults were still alive even after 7 days at -10 degrees C, while complete mortality was achieved only after 1 day at -15 degrees C. Eggs of L. bostrychophila were the most cold-tolerant life stage, as survival was observed even after 3 days at -15 degrees C. The results of the present study provide the first data set on which all life stages of P. interpunctella and L. bostrychophila are evaluated for their susceptibility to cold treatments in a standardized series of exposures and temperatures. These results are expected to further encourage the real world application of cold treatments for the disinfestation of durable stored-products.