Effects of Encarsia formosa (Hymenoptera: Aphelinidae) parasitism on the feeding preference and performance of the whitefly predator Serangium japonicum (Coleoptera: Coccinellidae)

The relationship among the whitefly Bemisia tabaci (Hemiptera: Aleyrodidae), its predator Serangium japonicum (Coleoptera: Coccinellidae), and its parasitoid Encarsia formosa (Hymenoptera: Aphelinidae) can be defined as intraguild predation (IGP). IGP represents an interaction that combines elements of both predation and competition between two species. In our previous study, predators ( S. japonicum ) often indirectly reduce the number of parasitoids ( E. formosa ) by consuming shared food resources, such as B. tabaci. To suppress whitefly outbreaks, a combination of parasitoids and predators is often released together using a mixed-species approach. However, the impact of the parasitic behavior of parasitoids on the feeding behavior of specific predators, such as S. japonicum, has not yet been well-studied. We conducted a laboratory study to examine how the parasitoid E. formosa affects the predation rates and performance of S. japonicum. Results indicate that S. japonicum shows a preference for non-parasitized whiteflies over parasitized ones, regardless of the availability of choices. Furthermore, we found a correlation between the preference for non-parasitized whiteflies and the duration of parasitization. As the developmental days of the parasitoid mummies increased, the food intake of the predatory group decreased significantly. Additionally, as the parasitoid mummy develops, S. japonicum spends more time exploring and probing the mummy before deciding whether to consume it. In summary, our study suggests that S. japonicum exhibits a significant preference for consuming non-parasitized whiteflies. Therefore, it is important to coordinate the release timing of S. japonicum and E. formosa in the biological control of B. tabaci.