| Combining morphological and molecular methods, the dominant mite specie of mites on jujube, pear, and walnut tree was identified in Xinjiang Korla, Aksu, Kashgar, Hotan.Sensitivity and resistance of different populations against acaricides were measured. A preliminary study of the biochemical mechanism of resistance in truncation spider mite and strawberry spider mite has launched, also the control effects of acaricides against mites were evaluated in field. Key points as follows.1. Mites collected from Korla, Aksu, Kashgar, Hotan jujube, the dominant mite specie is truncation spider mite(Tetranychus truncatus). Mites collected from Korla pear, Aksu walnut the dominant mite specie is strawberry spider mite(Tetranychus turkestani).2. Using the slide-dipping method measured the sensitivity and resistance of truncation spider mite and strawberry spider mite against acaricides.The baseline sensitivity of acaricides against truncation spider mite and strawberry spider mite was established.The results showed that the relative toxicity of 7 acaricides to both truncation spider mite and strawberry spider mite was, emamectin benzoate >pyridaben>fenpyroximate>bifenazate>azacyclotin>chorpyriphos>propargite. The LC50 of truncation spider mite female adults were 0. 006 mg / L、0.148 mg / L、0.192 mg / L、0.841 mg / L、2.519 mg / L、3.586 and 37.479 mg / L, respectively. The LC50 of strawberry spider mite female adults were 0. 006 mg / L、0.174 mg / L、0.392 mg / L、0.744 mg / L、1.046 mg / L、5.376 mg / L and 11.325 mg / L, respectively. Resistance detection results showed that: Most truncation spider mite strains showed resistance to chlorpyrifos, of all the tested strains,KAZ3、AAA91、HNZ10 strains developed 7584.2、506.5、197.7 fold resistance to chlorpyrifos, respectively.All the field strains developed 5.2-47.0 fold、3.3-18.5 fold、3.0-25.8 fold、1.3-6.0 fold、1.2-9.9 fold 、1.8-75.6 fold resistance to fenpyroximate, propargite, pyridaben, emamectin benzoate, azocyclotin and bifenazate,respectively.Most strawberry spider mite strains showed significant resistance to chlorpyrifos.Strains developed 20.5-4341.1 fold resistance, respectively. The HNH10、KSY1 strains developed 246.5、113.7 fold resistance, respectively. The HNH10 strain showed the highest resistance to pyridaben, fenpyroximate, azocyclotin, propargite, developed 5529.8、58.0、207.0、779.8 fold resistance, respectively.To bifenazate, strains developed 5.2-19.9 fold resistance.3. Biochemical resistance mechanism of truncation spider mite and strawberry spider mite were studied.The major resistance mechanism of truncation spider mite HNZ10 strain to fenpyroximate, pyridaben, bifenazate was the increasing of the activity of carboxylesterases(CarE), alkaline phosphatase(ALP) and mixed function oxidase(MFO); to propargite, chlorpyrifos and azocyclotin were the decreasing of the activity of acetylcholinesterase(AchE). The major resistance mechanism of truncation spider mite AAD23 strain to fenpyroximate, bifenazate, pyridaben was the increasing of the activity of carboxylesterases(CarE), alkaline phosphatase(ALP). The decreasing of the susceptibility of AchE and increasing of the activities of ACP and GST played an important role in causing resistance of truncation spider mite AAA91 strain.The strawberry spider mite HNH10 strain got resistance to emamectin benzoate, pyridaben, azacyclotin, fenpyroximate, chorpyriphos and propargite. The activities of CarE、ACP 、ALP 、MFO、 GST in HNH10 strain were higher than KSY1 strain, which means the resistance was related with the increasing of the activities of these ezymes in HNH10 strain.4. The control effects of 8 acaricides against truncation spider mite and strawberry spider mite were evaluated in field using foliar spraying. The results showed that: Control effects of bifenazate, pyridaben, azocyclotin against jujube truncation spider mite and strawberry spider mite during 1d- 14 d after application were all over 90%. To jujube truncation spider mite, 1d after application, control effect of chlorpyrifos was 94.52%, 14 d after application, dropped to 51.89%, the control effect dropped significantly. Control effects of fenpyroximate, propargite and emamectin benzoate were over 80% after 1d application, but the high effect can not last long. To strawberry spider mite on pear tree, propargite and fenpyroximate got high control effect, 7d after application, the control effects were between 86.59%-93.26%.Control effects of chlorpyrifos, pyridaben and emamectin benzoate can not last long, 14 d after application, dropped to 61.08%-72.86%.The control effects of bifenazate and azocyclotin against strawberry spider mite on walnut tree were between 92.50%-99.75% after 1d-14 d application. 1d after application, control effects of chlorpyrifos, fenpyroximate and emamectin benzoate were between 76.94%-84.17%, 14 days after application, the control effects fell to-0.40%,- 1.91% and 38.92%, respectively. |
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