Hypoaspis miles is a soil-dwelling predatory mite commercially available for biological control of fungus gnats, Bradysia sp., in greenhouses. Life stages of H. miles, including egg, larva, protonymph, deutonymph and adult, were exposed to five different dosages of the miticide Kelthane® 50W and a water control to identify the most susceptible life stage, and a Kelthane dosage giving intermediate mortality appropriate for a positive control in subsequent evaluations. Experimental units consisted of two 22 x 22 sq mm glass fiber filter paper supported by two 22 x 22 sq mm cover glasses, and separated by a polycarbonate ring (3-mm high, 15-mm diameter). The protonymph stage was considered appropriate for exposure to pesticides in the evaluation of lethal and sub-lethal effects due to the degree of susceptibility and duration in the life-stage. Pesticides evaluated included the insecticides Adept®, Distance® and Duraguard® ME, and the fungicides Aliette® WDG, Banrot® 40W and Subdue® Maxx. Protonymphs were exposed for 24, 48 and 72 h to the maximum recommended label rate of the three insecticides and three fungicides, Kelthane and water as controls for evaluation of lethal effects. Duraguard ME caused 100% mortality of protonymphs, while the mortality range for the other pesticides was 5.8 to 30.4% after 72 h. Evaluation of sub-lethal effects of the selected pesticides, with the exception of Duraguard ME, resulted in a prolonged duration of the protonymphal stage, but no significant effect was detected on the duration of the deutonymphal stage. Experiments to determine sub-lethal effects are in progress.
Species 1: Acari Hypoaspididae Hypoaspis miles
Keywords: Biological control, Pesticide
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