Compatibility of chlorantraniliprole with the generalist predator Coccinella septempunctata L. (Coleoptera: Coccinellidae) based toxicity, life-cycle development and population parameters in laboratory microcosms

Abstract

Coccinella septempunctata is a common insect predator that provides biological control of many destructive arthropod pests. An assessment of the toxicity of pesticides to predators is a necessary component of Integrated Pest Management (IPM) strategies. In order to evaluate the risks of field insecticide application, we studied the influence of chlorantraniliprole on C. septempunctata larvae using different exposure doses. Chlorantraniliprole exhibited low contact toxicity against 2nd instar larvae of C. septempunctata with the LR50 was 482.7063 g a.i. ha−1 by after a 72-h exposure. In a long-term test, the LR50 of chlorantraniliprole for C. septempunctata decreased from 88.97 to 58.22 g a.i. ha−1, while the hazard quotient (HQ) values were below the threshold value of 2 during the entire observation period. This indicated a low toxicity risk from insecticide exposure. The total effect (E) suggested that chlorantraniliprole could be classified as harmless/slightly harmful to C. septempunctata below/at 200% of the MRFR (the manufacturer maximum recommended field rate) of 120 g a.i. ha−1. We also determined no observed effect application rates (NOERs) of chlorantraniliprole on survival (7.5 g a.i. ha−1), developmental time (15 g a.i. ha−1) and fecundity (30 g a.i. ha−1). Chlorantraniliprole significantly reduced the pupation rate, adult emergence, egg hatchability, and predation success. Population parameters, including R0, r, λ, and T were significantly affected when C. septempunctata were treated with chlorantraniliprole at higher label rates. These results demonstrated that the use of chlorantraniliprole may reduce C. septempunctata population levels and the level of biological control provided by this species.