Neoseiulus californicus (Acari: Phytoseiidae) chemical impaired functional response type assessment preying on Panonychus citri (Acari: Tetranychidae)

This study evaluated sublethal effects of the insecticides SYP-9625, abamectin, vegetable oil, and EnSpray 99 on the functional responses of the predatory mite Neoseiulus californicus, highlighting their potential disruption of biological control functions. When predators fed on all stages (eggs, immature, and adults) of Panonychus citri without insecticides, they exhibited a type II functional response. Sublethal exposure to SYP-9625 and vegetable oil altered the predator's functional response curves without changing their response type compared to controls. Exposure to abamectin resulted in distinct functional response shifts, causing type I, type II, and type III responses when N. californicus fed on egg, immature, and adult stages of the pest, respectively. Exposure to EnSpray 99 led to a type I functional response in predators consuming immature and adult prey stages, characterized by non-significant linear parameters. The prey consumption rate was significantly impaired by abamectin, followed by EnSpray 99 and SYP-9625, compared to the control, while vegetable oil treatments increased predation rates by attracting predators. The fertility rate of N. californicus showed significant differences between vegetable oil and SYP-9625 treatments across impaired pest life stages. Abamectin and EnSpray 99 demonstrated the lowest compatibility with biological control, while vegetable oil increased predator attack rates and improved predator efficiency against P. citri. This study suggests that sublethal pesticide exposure can significantly alter predator behavior and efficiency. Integrated chemical-biological control strategies utilizing selective pesticides like vegetable oil show promise for citrus pest management but require further field validation.