Residual efficacy of synthetic acaricides and natural products for <i>Tetranychus urticae</i> Koch on cotton

Abstract

This study evaluated the residual efficiency of synthetic acaricides and natural products upon Tetranychus urticae females mortality and fecundity. The synthetic acaricides fenpropathrin, chlorfenapyr, diafentiuron, abamectin, spiromesifen, the oil emulsions of neem (Azadirachtin 1% and Azadirachtin A/B), Jatropha curcas and Ricinus communis were used. Plants were sprayed with the synthetic acaricides at commercial concentration, and the naturals at 1% concentration. Leaves of treated and untreated plants were collected at the intervals of 3h, 1, 2, 4, 8 and 16 days after spraying. Leaf discs of 3.5 cm diameter were infested with 15 T. urticae females. Mortality and fecundity were evaluated 48h after infestation. Percentages of mortality and oviposition reduction of treatments, compared to control, were calculated. Fenpropathrin, chlorfenapyr, diafenthiuron, and abamectin promoted females mortality over 98% up to the fourth evaluation. The greatest fecundity reduction was obtained for fenpropathrin, diafenthiuron, abamectin, and spiromesifen. Natural products were effective on mortality only at the first evaluation, however, oviposition reduction varied among treatments. All treatments are promising for the two spotted mite management, except for R. communis.