Larger is better in the parasitoid eretmocerus warrae (Hymenoptera: Aphelinidae)

Abstract

Eretmocerus warrae (Hymenoptera: Aphelinidae) is a specialist parasitoid that is used for the control of the greenhouse whitefly, Trialeurodes vaporariorum (Hemiptera: Aleyrodidae). We investigated how temperature affects the body‐size, life‐time oviposition, and longevity of E. warrae at different stages of life. The body‐sizes of both this parasitoid and its host are influenced by temperature. Body‐volume indices that reflect body‐sizes fell by 47.7 % in T. vaporariorum compared with 57.6% in E. warrae when temperature increased from 20 to 32 °C. The life‐time oviposition of female adults of E. warrae that grew at the immature developmental temperature of 20 °C was 86 ± 22 eggs, more than 66 ± 11 eggs at 26 °C, and 65 ± 23 eggs at 32 °C. Besides the influence on fecundity, temperature also influences the oviposition behaviour at the adult stage. More eggs were oviposited at 20 and 26 °C than at 32 °C. Higher temperatures reduced survival in the immature developmental stages and longevity in adults. Adult females lived for a maximum of 8.9 ± 1.8 days at 20 °C and laid a maximum of 97.4 ± 23.2 eggs when reared at 20 °C and maintained at 26 °C as adults. Adult body‐size is positively correlated with life‐time oviposition but not adult longevity. The results imply that temperature influences the nature of interactions between a parasitoid and its host. Larger wasps can live longer and parasitise more hosts, which should improve their performance as biological control agents.