Effect of afidopyropen on the functional response and associated parameters of Trichogramma evanescens

Afidopyropen, with a unique mode of action that modulates the chordotonal organ transient receptor potential vanilloid (TRPV) channel, serves as a promising insecticide against sap-sucking pests, particularly aphids. However, when targeting aphids, afidopyropen can affect non-target organisms such as Trichogramma species inhabiting the same habitats. The information regarding the effects of afidopyropen on Trichogramma species is limited, and there is an urgent need to expand our knowledge in this area. This study investigated the effects of afidopyropen treatment on the type of functional response and associated parameters, such as attack coefficient and handling time, of Trichogramma evanescens Westwood (Hymenoptera: Trichogrammatidae) females treated at the pupal stage. The findings clearly revealed that afidopyropen treatment did not change the type of functional response since both afidopyropen and control-treated parasitoids exhibited a type III functional response. Afidopyropen treatments did not affect the host handling time of the parasitoid either. However, the parasitoids treated with afidopyropen had a lower attack coefficient compared to the control group. The findings of this study suggest that afidopyropen does not alter the host handling strategy of T. evanescens, although it impaired the attack coefficient and may pose a threat to the natural effectiveness of the parasitoid. This current study highlights the requirement of further investigations aimed at determining the effects of afidopyropen on non-target insects.