Effect of fungicides on the functional response of Neoseiulus longispinosus (Phytoseiidae) to Tetranychus urticae (Tetranychidae) eggs

Abstract

ABSTRACT The present study was performed to investigate the effect of fungicides (mancozeb, copper oxychloride, thiophanate methyl, and metalaxyl + mancozeb) on the functional response of a phytoseiid predator, Neoseiulus longispinosus (Evans), to eggs of Tetranychus urticae Koch. The predatory mite females were treated with fungicides and after 48 h, progeny from live females were evaluated for the residual toxicity effect on the functional response of predatory mites. All the tested stages of N. longispinosus (protonymph, deutonymph, adult female and male) exhibited a type II functional response to eggs of T. urticae in fungicide treatments and untreated control. With an increase in prey density, the number of prey consumed increased, then levelled off and the proportion of prey consumed decreased. When compared with control, no significant differences across treatments were observed in the attack rate and handling time of the predator stages. The adult female showed maximum searching efficiency with attack rate and handling time ranging between 0.226–0.204 h−1 and 3.069–3.457 h, respectively, across fungicide treatments. This study suggests that even under the exposure of fungicides, N. longispinosus could possess a promising predatory potential against T. urticae on tomato.