Insight into the success of whitefly biological control using parasitoids: evidence from the Eretmocerus warrae-Trialeurodes vaporariorum system.

BACKGROUND: Mechanisms behind the success and failure of whitefly biological control using parasitoids are largely unknown. Here we use the Eretmocerus warrae-greenhouse whitefly system to investigate how the fluctuating density of the parasitoid and its host affects three key parasitoid fitness parameters, host searching, host feeding and parasitization, providing critical knowledge for evaluation and development of whitefly biological control programmes. This is the first such study in a parasitoid-whitefly system. RESULTS: Models used and developed here show that (1) both host feeding and parasitism fit a type II functional response; (2) overall parasitoid-caused whitefly mortality significantly increases with growing density of both organisms and the parasitoid density has a significantly more positive effect; (3) with a pro-synovigenic nature, E. warrae allocate significantly more resources to parasitization than to host feeding activity in low whitefly density and high parasitoid density; and (4) low mutual interference among searching parasitoids encourages parasitoid aggregation on host patches of high density. CONCLUSION: Regardless of greenhouse whitefly density, the pest can be effectively controlled by release of E. warrae. Our study provides insight into the success of whitefly biological control programmes using the parasitoid augmentation approach. Models used and developed here can also be employed to evaluate biological control programmes for other parasitoid-whitefly systems. © 2017 Society of Chemical Industry.