This study was carried out to evaluate the residual toxicity of some pesticides used in citrus orchards, on Neoseiulus californicus (McGregor) under laboratory conditions. The residual contact bioassay method was adopted. Citrus leaves of the variety "Pêra" were sprayed in a Potter tower. The products' residual toxicity was evaluated at two hours and 1, 3, 5, 7, 10, 14 and 21 days after treatment. Ten adult females of N. californicus were transferred to each arena together with an enough amount of Tetranychus urticae to feed the predator. Mortality evaluations were performed at 72 hours after transferring the predaceous mites to the arenas. The pesticides acrinathrin, deltamethrin, dinocap, sulphur, fenpropathrin, fenbutatin oxide and propargite did not cause significant mortalities to the adults of N. californicus. Abamectim, azocyclotin and cyhexatin caused mortalities of 29.8, 24.0 and 34.1%, respectively, for N. californicus adults exposed to two-hour pesticide residues. Dicofol, pyridaben and chlorfenapyr caused 100% of mortality to the predators exposed to the two-hour acaricide residues. Abamectin provoked significant mortalities for a period shorter than one day. Residues of azocyclotin, cyhexatin, dicofol, pyridaben and chlorfenapyr caused significant mortalities for periods of 1, 1, 10, 10 and 21 days, respectively. The results of this study provided basic information for choosing the adequate pesticides to be used in citrus orchards in which N. californicus is present, or in those the predator will be released. The results are also useful for the decision of the best releasing time for N. californicus in the field, after pesticide applications. Studies carried out in the field are still necessary to understand better the effect of these pesticides under the predaceous mite.
Predatory mite; citrus; biological control; sensibility to agrochemicals
