Behavioral and acaricidal effects of the chlorfenapyr and acequinocyl on the predatory mites, Neoseiulus californicus and Phytoseiulus persimilis (Acari: Phytoseiidae)

Abstract

The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is a major pest of various plants with a worldwide distribution. Extensive use of chemical pesticides has led to the development of resistance in this pest, making biological control agents a viable alternative for its management. The predatory mites, Neoseiulus californicus (McGregor) and Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) are the most important predators of the two-spotted spider mites. In this study, the toxicity of two acaricides chlorfenapyr and acequinocyl, on these predators was evaluated, and the walking behavior of predatory mites after exposure to residues of the pesticides was assessed using a video tracking system. Based on the results, the LC₅₀ values of both acaricides was estimated to be higher than their field concentration, and chlorfenapyr was found to be five-fold more toxic than acequinocyl. In the behavioral assay, both acaricides significantly affected the distance and speed of walking, resting time, and frequency of stops of both predatory mites. In the escape assay, both compounds had an irritable effect on both predatory mites, as the mites avoided areas contaminated with pesticide residues and their presence in the untreated area was significantly longer than in the treated area (P < 0.05). However, the study found no correlation between toxicity and irritability. According to the results of this study, N. californicus and P. persimilis possess the ability to detect the presence of pesticide residues in their environment and try to avoid them. Moreover, both compounds are at low risk to these mites, but acequinocyl is much safer and is a suitable option for use in integrated pest management.

Keywords: Behavior; Bioassay; Biological control; Predatory mites; Repellency.