Factors Affecting Progeny Production and Sex Ratio of Gryon aetherium (Hymenoptera: Scelionidae), a Candidate Biological Control Agent for Bagrada hilaris (Hemiptera: Pentatomidae)

Abstract

Manipulating the factors that influence progeny production and sex ratio in parasitoids can help maximize the production of quarantine bioassays and/or mass releases. In a series of experiments, we studied the effects of several factors on offspring production and sex ratio in the parasitoid Gryon aetherium (Hymenoptera: Scelionidae), a candidate biological control agent for Bagrada hilaris (Hemiptera: Pentatomidae). Progeny production was influenced by maternal age and dropped when females were 24 or 28 days old and decreased on the second day of exposure. Overall, the offspring sex ratio was highly variable in G. aetherium and was affected by the duration of exposure, with higher proportions of females emerging after one day of exposure than after two days, but was not affected by female density, female age/host deprivation, or temperature during oviposition. Progeny production was affected by the temperature during oviposition and was highest at 26.6 °C. The results indicate that production of G. aetherium can be maximized at one day of exposure, using females that are less than 24 d old, and at temperatures of around 26 °C.