Survival of Plodia interpunctella (Hübner) larvae treated with 98% N 2 and the life history of their next generation.

Understanding the development and reproduction of insects surviving controlled atmosphere treatment may help in developing sound pest management strategies. The developmental duration, survival percentage, and oviposition of and its generation were determined after the fifth instar larvae (the last-stage larvae) were exposed to 98% for different exposure times. The survival percentage of the last-stage larvae treated with 98% for 6, 4, 1.5, and 0 day was 70, 80, 91, and 100%, respectively when measured 24 h after treatment. The survival percentage of the last-stage larvae that developed to pupae was 37, 55, 73, and 96%, corresponding to the different exposure times. The developmental time needed to pass from pupa to adult emergence of specimens treated as the last-stage larvae were 8, 7, 6, and 6 days corresponding respectively to high treatment after 6, 4, 1.5, and 0 day of exposure. The mean number of eggs laid by the subsequent females developed from the treated last-stage larvae was 35, 66, 81, and 123, respectively. The oviposition inhibition ratio of the generation decreased by more than 33% compared with that of the parental generation. When the last-stage larvae were exposed to 98% for longer than 4 days, the immature developmental time of surviving individuals in the generation was delayed more than 6 days due to slower egg hatching and longer development of the first and second instar larvae stages. The population trend index of the generation was lower when raised from the treated last-stage larvae than those from untreated controls.