Prolonged Sublethal Imidacloprid Exposure Reduces the Functional Response and Searching Efficiency of Orius similis Against Frankliniella occidentalis

Abstract

ABSTRACT Neonicotinoid residues can compromise biological control in integrated pest management, yet the role of exposure duration is rarely quantified for predatory bugs. Here, we compared short‐term (24 h) and long‐term sublethal exposure to imidacloprid (LC 10 and LC 20 ) on the predatory performance of Orius similis against the western flower thrips Frankliniella occidentalis . Across nymphal instars and adults, prolonged exposure consistently reduced daily predation and weakened functional response parameters, with lower attack rates ( a ), longer handling times ( T h ) and reduced control capacity ( a / T h and 1/ T h ). All treatments conformed to Holling type II, but long‐term exposure amplified the decline in searching efficiency across prey densities. These results indicate that chronic, low‐dose imidacloprid pressure can cumulatively erode predator efficacy even when acute toxicity is low, highlighting the need to account for exposure duration when coordinating imidacloprid applications with releases or conservation of Orius ‐based biocontrol programs.