Toxicidade diferencial de agroquímicos a Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) e Tetranychus urticae Koch (Acari: Tetranychidae) em morangueiro

Abstract

This work aimed to evaluate the differential toxicity of pesticides to populations of the mite species Neoseiulus californicus (McGregor) and Tetranychus urticae Koch collected from commercial crops of strawberry (Fragaria sp.) in Atibaia county, State of São Paulo, Brazil. In the test of acute toxicity of pesticides, adult females of N. californicus received the pesticide treatment under Potter spray tower. The predaceous mite N. californicus showed the same or higher tolerance than T. urticae to various pesticides in laboratory. The highest difference was observed to the acaricide propargite, for which the predaceous mite was 25.1 times more tolerant than the two-spotted spider mite. This phytoseiid was also 4.7, 2.9 and 2.5 times more tolerant than T. urticae to chlorfenapyr, fenpyroximate, and cyhexatin, respectively. In the test of residual toxicity of pesticides, the chemicals were sprayed on plants of strawberry in the field. Leaves were collected after different periods from the treatment and artificially infested with adult females of N. californicus. The mortality was assessed 48h or 72h after treatment. Fenpyroximate, fenpropathrin, dimethoate, propargite, sulphur, and benomyl were innocuous to N. californicus. Chlorfenapyr, cyhexatin, and abamectin were significantly harmful to the predaceous mite causing initial mortality rates between 37.5% and 57.5%. The use of predaceous mites like of this population of N. californicus, which presents low susceptibility to various pesticides can be very useful for programs of management of T. urticae on strawberry in Brazil.