Sublethal effects of organophosphorus insecticide phoxim on patch time allocation and oviposition behavior in a parasitoid wasp Meteorus pulchricornis

Abstract

Parasitoid wasps are key agents for controlling insect pests in integrated pest management programs. Although many studies have revealed that the behavior of parasitic wasps can be influenced by insecticides, the strategies of patch time allocation and oviposition have received less attention. In the present study, we forced the endoparasitoid Meteorus pulchricornis to phoxim exposure at the LC30 and tested the foraging behavior within patches with different densities of the host, the larvae of the tobacco cutworm Spodoptera litura. The results showed that phoxim treatment can significantly increase the patch-leaving tendency of female wasps, while host density had no impact. The number of oviposition and the number of previous patch visits also significantly influenced the patch time allocation decisions. The occurrence of oviposition behavior was negatively affected by phoxim exposure; however, progeny production was similar among patches with different host densities. Phoxim exposure shaped the offspring fitness correlates, including longer durations from cocoon to adult wasps, smaller body size, and shorter longevity. The findings of the present study highlight the sublethal effects that reduce the patch residence time and the fitness of parasitoid offspring, suggesting that the application of phoxim in association with M. pulchricornis should be carefully schemed in agroecosystems.

Odorant-Binding Protein 6 Contributes High Binding Affinity to Insecticides in a Parasitic Wasp Meteorus pulchricornis (Hymenoptera: Braconidae)

“…pulchricornis, implying a potential impact of insecticides on the olfactory recognition of M. pulchricornis . However, the interaction between insecticides and OBPs has not been explored in M.…”

“…21 In the previous study, we found that the occurrence of phoxim exposure harmed the foraging and oviposition behaviors and exhibited a decrease in the number of host visits in M. pulchricornis, implying a potential impact of insecticides on the olfactory recognition of M. pulchricornis. 26 However, the interaction between insecticides and OBPs has not been explored in M. pulchricornis so far; whether MpulOBPs can bind to the insecticides remains to be elucidated. In this study, we further investigated the binding affinities of MpulOBP6 and found that the binding mechanism of MpulOBP6 to three insecticides (phoxim, chlorpyrifos, and chlorfenapyr) and several important amino acid residues were determined that play a crucial role in their binding processes.…”