Toxicity of bifenazate and its principal active metabolite, diazene, to Tetranychus urticae and Panonychus citri and their relative toxicity to the predaceous mites, Phytoseiulus persimilis and Neoseiulus californicus.

Bifenazate is a novel carbazate acaricide discovered by Uniroyal Chemical (now Chemtura Corporation) for the control of phytophagous mites infesting agricultural and ornamental crops. Its acaricidal activity and that of its principal active metabolite, diazene, were characterized. Bifenazate and diazene had high toxicity and specificity both orally and topically to all life stages of Tetranychus urticae and Panonychus citri. Acute poisoning was observed with no temperature dependency. No cross-resistance was found to mites resistant to several other classes of acaricides, such as tebufenpyrad, etoxazole, fenbutatin oxide and dicofol. Bifenazate remained effective for a long time with only about a 10% loss of efficacy on T. urticae after 1 month of application in the field. All stages of development of the predatory mites, Phytoseiulus persimilis and Neoseiulus californicus, survived treatment by both bifenazate and diazene. When adult females of the two predatory mite species were treated with either bifenazate or diazene, they showed a normal level of fecundity and predatory activity in the laboratory, effectively suppressing spider mite population growth. Even when the predators were fed spider mite eggs that had been treated previously with bifenazate, they survived. These findings indicate that bifenazate is a very useful acaricide giving high efficacy, long-lasting activity and excellent selectivity for spider mites. It is, therefore, concluded that bifenazate is an ideal compound for controlling these pest mites.