Laboratory Studies to Elucidate the Residual Toxicity of Eight Insecticides to <I>Anystis baccarum</I> (Acari: Anystidae)

Abstract

Anystis baccarum (L.) [=Anystis agilis (Banks)] (Acari: Anystidae) is a common predatory mite recently identified in apple (Malus spp.) orchards and in vineyards (Vitus spp.) in Québec, Canada. Studies of its susceptibility to pesticides used in these crops need to be carried out to encourage integrated pest management programs. A laboratory evaluation of methoxyfenozide, acetamiprid, thiamethoxam, imidacloprid, spinosad, phosmet, carbaryl, and lambda-cyhalothrin showed that residues of lambda-cyhalothrin, phosmet, and carbaryl were highly toxic in 48-h petri dish bioassays. The field rate of lambda-cyhalothrin is 0.0184 g (AI) /liter, which is 26-fold the estimated LC50 of 0.0007 g (AI) /liter) for this predator. The field rate for phosmet is 0.6000 g (AI) /liter, which is 118-fold the LC50 for phosmet, which is 0.0051 g (AI) /liter), and the field rate for carbaryl is 1.960 g (AI) /liter, which is 784-fold the estimated LC50 of 0.0025 g (AI) /liter). Five other insecticides, methoxyfenozide, acetamiprid, thiamethoxam, imidacloprid, and spinosad, were evaluated and found to be nontoxic.