Toxicity of Three Acaricides to the Predatory Mite, Neoseiulus bicaudus (Acari: Phytoseiidae) and Their Impact on the Functional Response to Tetranychus turkestani (Acari: Tetranychidae)

Abstract

The use of chemical pesticides particularly acaricides can reduce the control efficacy of natural enemies. The objectives of this study were 1) to evaluate the toxicity of three acaricides to the phytoseiid mite Neoseiulus bicaudus (Acari: Phytoseiidae) by spraying acaricides on N. bicaudus adult females and 2) to determine the effect of these acaricides on the functional response of different stages of N. bicaudus to the prey Tetranychus turkestani Ugarov & Nikolski (Acari: Tetranychidae). The results indicated that the survivability of N. bicaudus differed among the three acaricides tested. Pyridaben exhibited the highest toxicity to N. bicaudus not only because it caused higher mortality but also because it reduced the peak consumption for adults and increased the peak consumption for deutonymphs of N. bicaudus. The two other acaricides, azocyclotin and bifenazate, also slightly reduced the peak consumption, but not significantly, and the overall functional response was not different from control, untreated predatory mites. Bifenazate (143-4,300 mg a.i./liter) was relatively nontoxic to N. bicaudus (less than 10% mortality) but highly toxic to T. turkestani (more than 95% mortality). Accordingly, bifenazate is the most suitable for maintaining N. bicaudus in the field. Combining bifenazate and azocyclotin with N. bicaudus is a possible strategy for T. turkestani management.

Keywords: azocyclotin; bifenazate; compatibility; predator mite; pyridaben.