Effects of short-term thermal stress on functional response and interspecific interaction of whitefly parasitoids

The functional response of a biocontrol agent, as well as its interactions with co-occurring species under thermal stress, are 2 crucial factors in evaluating its ability to control arthropod pests in the context of climate warming. Encarsia formosa (Gahan) (Hymenoptera: Aphelinidae) is one of the most extensively utilized biological control agents for the whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). In the present study, we evaluated the effects of short-term heat stress on the functional response and host control efficacy of En. formosa, as well as the interspecific interactions between this parasitoid and the co-occurring parasitoid Eretmocerus hayati (Zolnerowich and Rose) (Hymenoptera: Aphelinidae). At all experimental temperatures, type II functional responses of En. formosa were observed in both parasitism and host feeding. The type of functional response remained unaffected by experimental temperature. Roger's model was utilized to fit the data. Based on the 95% confidence interval, pairwise comparisons of searching rate (a) and handling time (Th) across temperature regimes yielded no significant differences. In most instances, the increased temperatures did not affect the host control efficacy of En. formosa. The coexistence of En. formosa and Er. hayati exhibited a negative impact on En. formosa's parasitism but a positive effect on that of Er. hayati across all temperature regimes. These findings provide valuable knowledge regarding the functional dynamics of En. formosa under climate warming and underscore the importance of understanding interspecific relationships among biocontrol agents to effectively optimize pest management strategies.