Keywords: 
• Panonychus cotri /
• resistance /
• toxicity test

Abstract: In order to timely understand the resistance of Panonychus cotri , guide chemical control and guarantee the economic benefit of the citrus gardens , the toxicity of 9 pesticides for this insect in Zhejiang was measured by means of slide maceration recommended by FAO of the United Nations . Results obtained show thatPanonychus cotri on citrus has created resistance to a number of pesticides to various extents .Isocarbothos was most highly resisted by the pest inHangbu of Quxian County ;Dicofol , amitraz , fenpropathrin and fentyroximate applied in Hangbu of Quxian , pyridaben applied in Huangyan City , isocarbothos applied in Xifangwu , Shangyutou and Xikou of Longyou County , and fenpropathrin applied in Xifangwu and Shangyutou of Longyou were highly resisted ;Isocarbothos used in Huangyan , dicofol used in Xifangwu , Shangyutou and Xikou of Longyou , amitraz used in Xifangwu and Xikou of Longyou , omethoate used in Hangbu of Quxian , and fenpropathrin used in Xikou of Longyou were also resisted ;Amitraz adopted in Huangyan , omethoate adopted in Xifangwu and Xikou of Longyou , cyhalothrin adopted in Hangbu of Quxian , pyridaben adopted in Xifangwu of Longyou , and hexythiazox adopted in Hangbu of Quxian were lowly resisted ;Dicofol applied in Huangyan , and cyhalothrin and fentyroximate applied in Xifangwu of Longyou were highly tolerated by the pest , but the pest was sensitive to cyhalothrin applied in Xikou of Longyou , hexythiazox applied in Xifangwu of Longyou and pyridaben applied in Hangbu of Quxian .Studies also show that its easy forPanonychus cotri to develop resistance to such pesticides as pyrethroid and the pest and pesticides have inter-resistance .The resistance to dicofol develops slowly and sensitivity resumes quickly .The resistance to such pesticides of heterocycle as fentyroximate and pyridaben either easily forms but disappears slowly .The strategies in resistance management of Panonychus cotri is suggested finally .