The last few years have seen the introduction of an unprecedented number of new classes of acaricides with novel or under-exploited modes of action, discovered by traditional screening. Acaricide research has uncovered several unrelated compounds that possess improved properties. Pyridaben, acequinocyl, diafenthiuron, etoxazole, spirodiclofen and bifenazate, in particular, are acaricides that are safe to beneficials, have low mammalian toxicity and short environmental persistence. Many of the new acaricides appear to affect mitochondrial respiration, and previously unknown targets affecting mite growth and development have been identified, offering new opportunities for mite control.

CONTENTS 7097 3.2. Discovery of Advanced Candidates SYP-1545, SYP-4288, and SYP-4380 7098 4. Conclusion 7098 Author Information 7099 Corresponding Author 7099 Present Address 7099 Notes 7099 Biographies 7099 Acknowledgments 7100 References 7100

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.

The biorational design of new miticides requires an understanding of the biochemistry and physiology of mites. This review considers the interaction and impact of existing miticides with the cuticle, nervous system, growth and development, metabolism, feeding and behaviour and assesses the potential of these as possible targets for miticide development. Considering the sites of action of some of the major miticides, GABAergic and octopaminergic transmission, and oxidative phosphorylation are attractive targets for further miticide development.

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