Efficacy of selected pesticides on Citrus Brown Mite, Eutetranychus orientalis (Acari: Tetranychidae) and the side effects on three predatory mites under citrus orchard conditions

Abstract

The present study has been conducted to evaluate the effect of two sprays of seven pesticides at recommended dose on citrus brown mite, Eutetranychus orientalis and the side effects on their predatory mites, Euseius scutalis, Amblyseius swirskii, Phytoseiulus persimilis (Acari: Phytoseiidae) under field conditions at 2022 & 2023 seasons. The obtained results show that, all tested pesticides achieved high reduction % of E. orientalis ranged between (82.1-90.0%) and (81.6-87.1%) after the 1st and 2nd sprays of 2022 season, where it ranged between (84.9- 88.7%) and ( 79.7- 88.7%) after 1st and 2nd sprays of 2023 season. Abamectin recorded the highest reduction % against the citrus brown mite, whereas Congest pesticide recorded the lowest reduction % after the two sprays along 2022 & 2023 seasons. As for the side effects of tested pesticides on associated predatory mites, all pesticides were safely for E. scutalis numbers recording decrease % between (18.4-28.6%) and (16.2 -26.1%) after the 1st and 2nd spray at 2022 season , where it ranged between (15.3- 29.1%) and (19.6-32.0%) after the 1st and 2nd sprays of 2023 season. On contrary, imidacloprid was unsafely for E. scutalis numbers recording the highest mean decrease % after 1st and 2nd sprays during the two seasons. Also, all tested pesticides were safely for A. swirskii numbers, after the 1st and 2nd sprays of the two seasons recording decrease (from 10.9 to 28.1%) & (24.4 to 31.4%) for the 2022 season, and (19-38.9%) & (18.7-39.4%) at 2023 season. On contrary, imidacloprid was unsafely for A. swirskii numbers recorded the highest decrease % after 1st and 2nd sprays during the two seasons. As for, Ph. Persimilis numbers, all tested pesticides were safely, where it recorded low decrease % ranged between (17-33.8%) & (20.4-34.8%) after the 1st and 2nd sprays of 2022 season, and (24.3-39%) & (20.2-28.9%) after the 1st and 2nd sprays of 2023 season. On the other side, imidacloprid was unsafely for Ph. persimilis numbers recording the highest decrease % after the 1st and 2nd sprays during the two seasons. The present study proved that all tested pesticides were high effective against E. orientalis and appeared to be safely and selective for associated predatory mites except imidacloprid which was very harmful for all tested predatory mites, and it could be concluded that the tested pesticides, Fenpyroximate, Hexythiazox , Congest , Spirodiclofen, Abamectin, and Chlorfenapyr could be used in the Integrated Pest Management (IPM) programs for E. orientalis at citrus orchards.