Effect of different food resources on longevity, ovarian dynamics and body nutrient levels of fruit fly parasitoids

Fruit fly parasitoids enjoy ample access to fallen or damaged fruits, which constitute sugar sources and could benefit wasp fitness in specific and biological control in general. In this study, we assessed a set of fitness parameters of the braconid wasp Diachasmimorpha longicaudata, fed on different diets. More specifically, we subjected both sexes of D. longicaudata to either simple or combined diets of guava juice, honey and pollen, and quantified the effect of these diets on parasitoid longevity, ovarian dynamics and (body) carbohydrate levels. Wasp longevity significantly differed between diets, being lowest on water (6.0 ± 2.3 days) and highest on honey (13.0 ± 6.8 days). At emergence, female D. longicaudata possessed 25.0 ± 14.6 mature eggs and increased to 108.0 ± 13.0 at six days of age, under honey and guava juice treatments. No differences were found in D. longicaudata egg maturation rates, between the different diets. Endpoint glycogen and total sugar levels of wasps greatly differed between the distinct diets. Glycogen levels were highest in honey and combined diets and lowest under guava juice and water treatments, while highest sugar levels were reported with honey and combined diets. In conclusion, the synovigenic parasitoid D. longicaudata benefits comparatively little from access to guava juice and attains superior fitness levels with access to high-sucrose sugar sources. Our work highlights the need of supplying natural (extra-) floral nectar sources or artificial sugar sprays to augment efficacy of D. longicaudata for fruit fly biological control.