Compatibility of reduced-risk pesticides with the non-target predatory mite Euseius scutalis (Athias-Henriot) (Parasitiformes: Phytoseiidae)

Euseius scutalis (Athias-Henriot) (Parasitiformes: Phytoseiidae) is one of the most abundant predatory mites in citrus orchards across the eastern Mediterranean region. Despite its ecological importance, information on the compatibility of reduced-risk pesticides with this species is limited. This study evaluated the toxic effects of six widely used reduced-risk pesticides: fosetyl-Al, prothioconazole + spiroxamine, proquinazid, tebuconazole, spinetoram, and spinosad on adult females of E. scutalis under laboratory conditions. Pesticides were applied at maximum recommended concentrations to simulate a worst-case exposure scenario. At 120 hours post-treatment, spinetoram and spinosad caused 100% mortality, while prothioconazole + spiroxamine caused 74% mortality. In contrast, fosetyl-Al, proquinazid, and tebuconazole caused lower mortality rates of 47, 52, and 59%, respectively, with no significant differences among them. Egg production was completely inhibited by spinetoram and spinosad and significantly reduced by prothioconazole + spiroxamine. Fosetyl-Al, proquinazid, and tebuconazole showed minimal impact on reproduction. These results indicate that spinetoram, spinosad, and prothioconazole + spiroxamine are highly toxic and may be incompatible with E. scutalis in integrated pest management programs, whereas fosetyl-Al, proquinazid, and tebuconazole could be safer for use in combination with this predator. Further semi-field and field studies are needed to confirm these laboratory findings.