EGG STORAGE OF Podisus nigrispinus (HEMIPTERA: PENTATOMIDAE) PREDATORS AT LOW TEMPERATURES

摘要

Podisus nigrispinus are bedbug predators that are used as biological control agents of defoliating larvae in eucalypt plantations. The mass rearing of natural enemies produces large numbers of insects, but the number of predators produced may not coincide with the timing of the outbreaks of pest populations in the field. The aim of this study was to evaluate the effects of different storage periods on the eggs of P. nigrispinus at low temperatures of 5, 13 and 15oC. The treatments consisted of periods of 5, 10, 15 and 20 days of storage of predator eggs at each temperature indicated. After the different periods of storage, the eggs were removed, and the egg viability, the survival and duration of nymphal instars and the sex ratio of emerged adults were evaluated. Egg storage at 5oC reduced the percentage of hatched eggs, while viability values close to 50% were observed for storage periods of up to 10 days at 13oC and up to 15 days at 15oC. For these treatments, the survival rates of nymphs were similar to those of the control. The different storage periods had no effect on the duration of the nymphal stage or the sex ratio of P. nigrispinus at any of the temperatures. Therefore, the storage temperature of 5oC caused the death of the majority of the embryos, while it is possible to store P. nigrispinus eggs up to 10 and 15 days at 13 and 15oC, respectively.