Sublethal imidacloprid impairs predatory performance of
Orius similis
against
Frankliniella occid
Xuefeng Fu, Yiru Li, Jinlong Zhang, Nian Yang, Dengrong Shen, Min Chen, Xiaoming Zhang Abstract
BACKGROUND
Sublethal pesticide risk to biological control agents is often judged by survival alone, although predators that survive exposure may still lose predatory performance. Here, we quantified the functional response of F 1 and F 2 Orius similis (third‐ to fifth‐instar nymphs and male and female adults) to second‐instar Frankliniella occidentalis after exposure to imidacloprid at the lethal concentrations causing 10% or 20% mortality (LC 10 and LC 20 , respectively) through residual contact or prey‐mediated ingestion.
RESULTS
All stages retained a Holling type II response, but the magnitude and expression of impairment were strongly stage‐, route‐, concentration‐, and generation‐dependent. Fifth‐instar nymphs and adults contributed most to prey suppression, whereas younger nymphs were most sensitive to performance loss. Residual contact tended to increase handling time, especially in younger nymphs, whereas prey‐mediated ingestion more consistently reduced attack rate; both routes affected multiple functional‐response parameters. Some control‐standardized deficits were evident in the F 2 generation, particularly in younger nymphs.
CONCLUSION
Sublethal imidacloprid eroded the predatory performance of O. similis in a route‐specific and generation‐dependent manner during continuous multigenerational exposure, indicating that compatibility with this predator should be judged using functional endpoints in addition to survival in integrated pest management programs. © 2026 Society of Chemical Industry.