Abstract

Ahmad Nadimi, Karim Kamali, Masoud Arbabi and Fateme Abdoli

Economically, the most important species are the polyphagous pest two-spotted spider mite called Tetranychus urticae Koch and the predaceous phytoseiid mite called Phytoseiulus persimilis Athias-Henriot which is successfully used as biological control agent in a number of agricultural ecosystems. To evaluate the toxicity of the two current miticides (abamectin and fenpyroximate) on predatory mite P. persimilis, two persistence tests were carried out under laboratory conditions and with four replicates per treatment using commercial formulations at highest recommended field concentration, half concentration and quarter concentration. The control block was treated with water. Assessments of the phsytoseiid were performed on mortality, escape of predators up to 5 days after the adult stage and reproduction of female during the first 5 days of the adult stage. Total effects (E) of the miticides were determined on the phytoseiid by combining lethal (mortality) and sub -lethal effects (fecundity). Persistence is classified by considering E suggesting that all fenpyroximate treatments and three days old residues of abamectin treatments would be the least compatible with P. persimilis but ten days old residues of abamectin treatments were favorable towards P. persimilis.