Effect of Temperature on Lifetime Reproduction of the Egg Parasitoid Ooencyrtus nezarae (Ishii) (Hymenoptera : Encyrtidae)

概要

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Parasitoid reproductive biology is one of the central issues in biological control with parasitoids because the successful production of parasitoids is essential to mass?rearing of effective biocontrol agents. Parasitoid's fecundity can be influenced by several physical factors, and temperature is an important factor among them. Ooencyrtus nezarae is a common egg parasitoid attacking several hemipterans including the bean bug Riptortus clavatus, a serious pest of soybean, and is a candidate agent for biological control of soybean pests. In the present study, the lifetime reproduction of O. nezarae was examined under different temperature conditions. O. nezarae was able to parasitize host eggs at a wide range of temperatures from 20 to 30 ?C, and the highest mean fertility, i.e., the maximum progeny production, was around 75.0 at 25 ?C. However, the lifetime production of progeny was largely reduced at 20 and 30 ?C conditions (33.5 and 36.0 parasitoid progeny, respectively). Parasitization was also affected by temperature; the lowest parasitism rates occurred at 20 and 30 ?C. The parasitism rate at 25 was 20.3%, and was significantly higher than those at other temperature conditions. However, temperatures within the range of 20?30 did not significantly alter the progeny sex ratio and clutch size of O. nezarae. The results suggested that 25 ?C was the optimal temperature for efficient mass rearing of O. nezarae