Acaricides – Biological Profiles, Effects and Uses in Modern Crop Protection

Acaricide is a pesticide designed to control harmful species of mites (Acari)1. In crop protection practices, acaricides are used against phytophagous mites, pests causing economic injuries to agricultural crops and ornamental plants. Until mid-twentieth century, in agroecosystems of low-level productivity, phytophagous mite populations usually stayed below economic injury levels, due to natural regulation by predatory mites and insects, their natural enemies. The concept of secondary pest outbreak was introduced on spider mites (Tetranychidae), the most important plant-feeding mites, as a paradigm. Advances in agricultural production after World War II, based on the extensive use of pesticides and fertilizers, irrigation and other cultural practices, induced increase in spider mite populations far above economic threshold (Huffaker et al., 1970; McMurtry et al., 1970; Jeppson et al., 1975; Metcalf, 1980). Grown under favourable conditions, host plants became high quality food sources for the mite pests, which gave rise to outbreaks of their populations and made it possible to compensate for the losses caused by predators’ activity. Moreover, widespread use of neuroactive insecticides (synthetic organic compounds used against insects as target pests, but toxic to other non-target insect and mite species as well) destroyed spider mite predators, generally more susceptible than their prey; on the other hand, heavy selection pressure by neuroactive insecticides caused emergence of tetranychid mite populations resistant to these compounds. Besides the resistance of spider mites and the elimination of their predators, as the primary causes, outbreaks are influenced by sublethal effects of pesticides on behaviour and physiology of pests and/or predators (Metcalf, 1980; Hardin et al., 1995; Dutcher, 2007). Spider mites, mostly polyphagous species, are common pests in modern agroecosystems worldwide, and some of them are among the most important crop pests. After Tetranychidae,