Acute toxicity of lethal and sublethal concentrations of neonicotinoid, insect growth regulator and diamide insecticides on natural enemies of the woolly apple aphid and the obscure mealybug

Catalina Radrigán-Navarro1*, Elizabeth H. Beers2, Andrés Alvear3, and Eduardo Fuentes-Contreras1
Based on the importance of using low-risk compounds to protect beneficial agents, the present study evaluated the acutetoxicity of lethal and sublethal concentrations of the insecticides thiacloprid, pyriproxyfen, and chlorantraniliprole onadults of Aphelinus mali (Haldeman), the main parasitoid of the woolly apple aphid, Eriosoma lanigerum (Hausmann). Similarly, acetamiprid, buprofezin, pyriproxyfen, chlorantraniliprole and cyantraniliprole were evaluated on adults of the parasitoid Acerophagus flavidulus (Brethés) and also on larvae and adults of the predator Cryptolaemus montrouzieri Mulsant, both species important natural enemies of the obscure mealybug, Pseudococcus viburni (Signoret). Natural enemies were exposed to insecticide residues of minimum recommended rate (1x) and between one to four concentrations (0.5x, 0.25x, 0.1x and 0.05x) of the minimum recommended rate on apple leaves. Our results indicate that thiacloprid was moderately harmful to A. mali at 1x, and acetamiprid was harmful to A. flavidulus causing 100% mortality from 0.1x to 1x concentrations. Buprofezin, pyriproxyfen and chlorantraniliprole were harmless or slightly harmful for both parasitoids. Cyantraniliprole was slightly harmful from 0.25x to 1x for A. flavidulus. For C. montrouzieri, acetamiprid was harmless or slightly harmful for larvae and adults on the concentrations evaluated. Buprofezin, pyriproxyfen and chlorantraniliprole were harmless for larvae and adults of C. montrouzieri. Cyantraniliprole was slightly harmful on larvae and moderatelyharmful on adults of C. montrouzieri at 1x. Our data suggest that buprofezin, pyriproxyfen and chlorantraniliprole could be compatible with the natural enemies evaluated, while thiacloprid and acetamiprid were less compatible with parasitoids than with the predator. Finally, cyantraniliprole seems to be less compatible than chlorantraniliprole at 1x with the natural enemies evaluated.
Keywords: Aphelinidae, Coccinellidae, ecotoxicology, Encyrtidae, integrated pest management, mortality.
1Universidad de Talca, Facultad de Ciencias Agrarias, Casilla 747, Talca, Chile. *Corresponding author (cradrigan@utalca.cl).
2Washington State University, Tree Fruit Extension Centre, 1100 N Western Ave., Wenatchee, Washington, USA.
3Xilema SpA Departamento de Investigación y Desarrollo, Ruta 64 km 2.5, Quillota, Chile.