| In order to investigate the differences in the sensitivity of the small brown planthopper,Laodelphax striatellus in different areas of Shandong Province,the toxicity of cyantraniliprole to the 3rd instar nymphs and adults of six populations collected from Tai'an,Laiwu,Yutai?from wheat and rice,respectively?,Jinan and Jiyang was determined by rice seedlings dipping method and topical application method in the laboratory,respectively.The effects of the sublethal dose(LD10,LD20 and LD30)on the activity of esterase?ESTs?,glutathione-S-transferase?GSTs?and mixed-function oxidase?MFO?in adults of L.striatellus were also measured.We also observed the changes of developmental duration,spawning amount and female longevity of the tested insects after being subjected to sublethal doses(LD10,LD20 and LD30)of cyantraniliprole,and established the life table of its F1 population.At the same time,in order to better select suitable pesticides for pest control in the field,we also compared the sensitivity changes of L.striatellus to imidacloprid,thiamethoxam,buprofezin and pymetrozine after the sublethal concentrations(LD10,LD20 and LD30)of cyantraniliprole were stressed.The main results are as follows:1.The results of rice seedlings dipping method showed that the LC50 values of cyantraniliprole to 3rd instar nymphs of 6 populations ranged from 8.5193 mg/L to 11.0524mg/L and to adults from 10.4245 mg/L to 12.4904 mg/L.The results of topical application method showed that the LD50 values of cyantraniliprole to the 3rd instar nymph of 6populations were between 0.9239×10-3?g/insect to 1.1318×10-3?g/insect and to adults from1.0933×10-3?g/insect to 1.2619×10-3?g/insect.The results showed that there were no differences in the sensitivity of L.striatellus to cyantraniliprole in different areas of Shandong Province,also no difference in the sensitivity to cyantraniliprole between the 3rd instar nymphs and adults in the same area.2.Under the treatment of the sublethal dose of cyantraniliprole(LD10,LD20 and LD30),the activities of three detoxification enzymes were enhenced in the adults of L.striatellus,and the GSTs activities were promoted the most significant.The GSTs may be involved in the formation of cyantraniliprole resistance in L.striatellus in the later period.3.After LD10,LD20 and LD30 concentrations of cyantraniliprole,the number of eggs laid by single female of F0 generation planthopper was decreased by 27.08%,31.67%and35.83%,respectively,which was significantly different from that of the control;the nymph duration,adult duration and total duration of F1 L.striatellus were significantly prolonged;compared with the control group,the female ratio?Fr?and hatchability?Ha?of F1 generation were not significantly different from the control group,but the fecundity?Fd?of F1 generation decreased by 28.31%,32.02%and 35.03%,respectively.The predicted number of offspring?N?and population growth trend index?I?are also lower than those of the control group.After treatment the sublethal dose of cyantraniliprole(LD10,LD20 and LD30),the relative fitness of L.striatellus was 0.69,0.67 and 0.62,respectively.The results showed that the application of cyantraniliprole to control rice pests not only had a lethal effect on the contemporary L.striatellus,but also had a certain inhibitory effect on the growth of its offspring population.4.The sensitivity to imidacloprid and thiamethoxam of the population stressed by the sublethal concentration of bromocyanamide increases,and increases with the increase of the treatment concentration of cyantraniliprole.The sensitivity to buprofezin also increased and the sensitivity to different agents showed as follows:Untreated population<LD10 treated population<LD30 treated population<LD20 treated population.The sensitivity to pymetrozine increased slightly but the difference is not significant. |
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