Sensitivity of pupae of lightbrown apple moth, Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae), to combinations of abiotic stresses
Abstract
Abstract Combinations of non‐chemical postharvest treatments were investigated as alternatives to methyl bromide fumigation for postharvest control of lightbrown apple moth, Epiphyas postvittana (Walker). A combination of a warm controlled atmosphere pulse (1.2 kPa oxygen at 29°C) followed by cold storage (0°C) resulted in high level mortality of pupae (the most resistant stage of the life cycle). Effects of rearing temperature were tested by measuring the stress resistance of pupae originating from two field populations using three levels of stress (low, medium and high), each involving 48 h under controlled atmosphere at 29°C followed by 3, 9 or 27 days at 0°C. No differences in resistance to stress were observed between the two populations at low‐ and medium‐stress levels (60 and 80% mortality, respectively) or high levels (100% mortality), and larval rearing temperature (14, 19 and 25°C) did not influence the subsequent stress resistance of pupae. Finally, the effects of age and weight on resistance to stress were investigated. Younger pupae (2–3 days old) had relatively higher resistance to disinfestation stress, while pupal weight (controlled for age) had no effect. These results suggest that disinfestation by the combined stresses may be effective over a range of environmental conditions and for different populations of E. postvittana .