Acaricide resistance in predatory mites of the genus Euseius (Acari: Phytoseiidae) and predation capacity on Brevipalpus yothersi (Acari: Tenuipalpidae)

Abstract

One of the main citrus diseases in Brazil is citrus leprosis, transmitted by the mite Brevipalpus yothersi Baker (Acari: Tenuipalpidae). The predatory mites Euseius citrifolius Denmark & Muma and Euseius concordis (Chant) (Acari: Phytoseiidae) are important natural enemies for the pest mite. The objective of this work was to evaluate the susceptibility of different populations of E. concordis and E. citrifolius, from citrus groves in the state of S˜ ao Paulo (SP), to the acaricides abamectin, fenpropathrin and chlorfenapyr; characterize the abamectin resistance in E. citrifolius, including studies on cross-resistance and biochemical mechanisms of resistance; and evaluate the predation capacity of an abamectin resistant population of E. citrifolius on B. yothersi. Significant differences in susceptibility to acaricides were observed among populations of E. citrifolius. Resistance ratios of 15.5 and 3.1 (times) were observed for abamectin and chlorfenapyr, respectively, comparing populations of E. citrifolius collected in the municipalities of Taquaral-SP and Bofete-SP. Studies with the synergist piperonyl butoxide indicated the involvement of cytochrome P450-dependent monooxygenases in the resistance of E. citrifolius to abamectin. Populations of E. concordis and E. citrifolius collected in Taquaral-SP showed low susceptibility to fenpropathrin, with LC 50 values at least 95 times higher than the recommended concentration for the control of Brevipalpus mites in citrus in Brazil. The population of E. citrifolius from Taquaral showed a high capacity for predation of B. yothersi larvae, with consumption of up to 49.4 larvae per adult female per day.