Short-term contact toxicity of seven fungicides onAnystis baccarum

Abstract

Anystis baccarum (L.) (Acari: Anystidae) is a predacious mite prevalent in organic apple orchards and IPM vineyards in Quebec, Canada. Each season, 11 to 15 fungicide sprays may be applied to control apple scab in orchards. Laboratory tests of fungicides showed that dry residues of sulfur (Microscopic Sulphur® 92 WP), captan (Maestro®80 DF), kresoxim-methyl (Sovran®50 WG), metiram (Polyram®80 WP), boscalid (Lance®70 WDG) and myclobutanil (Nova®40 WP) were harmless toA. baccarum adult mites. In contrast, a dried residue of mancozeb (Dithane®M-45) was moderately toxic at the field rate and the LC50 was estimated at 1.88 g a.i.l−1 (1.2-fold the field rate). These findings are only part of the toxicity attributes of these fungicides, since only effects on adults were studied. Once a reliable rearing technique forA. baccarum is developed, effects on immatures, fecundity and egg hatch should be evaluated to complete our understanding of the effects of these fungicides on this predator.