Carbohydrate diet and reproductive performance of a fruit fly parasitoid, Diachasmimorpha tryoni

Augmentative releases of parasitoid wasps are often used successfully for biological control of fruit flies in programs worldwide. The development of cheaper and more effective augmentative releases of the parasitoid wasp Diachasmimorpha tryoni (Cameron) (Hymenoptera: Braconidae) may allow its use to be expanded to cover Queensland fruit fly, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae), a serious pest of many vegetables and most fruit production in Australia. This demands a fuller understanding of the parasitoid's reproductive biology. In this study, mating status, fecundity, and size of female D. tryoni were determined under laboratory conditions. A range of pre-release diets, 10% concentrations of honey, white sugar, and golden syrup, were also assessed in the laboratory. Mature egg loads and progeny yields of mated and unmated parasitoid females were statistically similar, demonstrating that mating status was not a determinant of parasitoid performance. Female lifespan was not negatively impacted by the act of oviposition, though larger females carried more eggs than smaller individuals, indicating a need to produce large females in mass-rearing facilities to maintain this trait. White sugar gave the highest adult female lifespan, while honey and golden syrup shared similar survivorship curves, all significantly greater compared with water control females. Pre-release feeding of D. tryoni, particularly with white sugar, may enhance the impact of released parasitoids on B. tryoni. These findings are important because honey is currently the standard diet for mass-reared braconids, but white sugar is less than one-third the cost of other foods; however further work is required to assess post-release performance of the parasitoid.