| Since the synthetic pesticides were applied into the rice pest control,its abuse has caused many negative problems such as ecological deterioration,increased resistance of target pests and decreased population of natural enemy insects.It will be important way by applying the new environmental friendly pest management for reducing the amount of chemical pesticides applied in rice field and improving the rice field ecological environment.In order to developing this new rice pest management,four representative rice planting areas of Hubei Province,including Wuxue(29°59'N,115°36'E),Suizhou(29°59'N,115°36'E),Jingzhou(30°15'N,112°31'E)and Wuhan(30°27'N,114°20'E)were selected for tests during two growing seasons(2016 and 2017).The particular effect of different control methods for the environmental friendly pest management was investigated by the independent field experiment.At the same time,we evaluated the combination of these methods on the main pests and eco-system in the rice field during the two growing seasons.The main results are as follows:1 The effect of each environment-friendly pest control method on the population of the rice pestRotary ploughing test: After using a rotary cultivator to break rice stubble from the ast growing season,the field was soaked for 5 days before rice transplant in 2016.The numbers of borers in the field were sampled and checked before and after the soaking.The results showed that the number of borers in rotated fields is 58% less than that in the unrotated fields.It suggested that the rotation and ploughing can effectively reduce the base number of overwintering borers.Insect trapping test with the solar frequency trembler grid lamp: One lamp per 1.33 ha was set up in the test area of Wuxue for capture of the rice pest.The results showed that more than 96% of the trapped insects were non-target insects,and there were mainly Coleoptera and Cymbidium(68%),followed by ladybugs(4.7%).However,the target insects(Pyralidae)pests was only 3.8% of the total trapped insects.Insect trapping test by sex pheromone lures: There were two treatments,one was using the water-basin trap and the other one using the sleeve-shaped trap in the two fields(25m ? 48m),with the same density in the field(One trap per 50 m distance).During the emergence period of Chilo suppressalis adult,the number of adult captured by traps was counted.The results showed that the average number of each trap per day in the water-basin trap was 47,which was significantly higher than that in the sleeve-shaped trap(2-3).The effect of two different formulations of attractant(common formulation and nanoparticle sustained-release formulation)on Cyrtorrhinus livdipennis: At the beginning of September 2017,Experimental field was sprayed attractant.The number of C.livdipennis adults and nymphs and the number of rice planthoppers in the test plots were counted every 2 days.The results showed that after 12 days of spraying with the common formulation of A atractant,the C.livdipennis adults and nymphs reached the peak(200 and 382 individuals per one hundred hills,respectively)and it was significantly higher than those in the field sprayed nanoparticles sustained-release agents and water control(P<0.05).Overall three treatments have no difference on the number of planthopper at almost all sampling times.2 Integration of different environment-friendly methods in the rice fieldThree treatments were designed for assessment: 1.Using integration of different environment-friendly methods of pest management,including rotarying old tillage and stubble before transplanting,planting attractive plant(Vetiveria zizanioides)and nectar plant(sesame and soybean),hanging sexual trap;2.Applying pesticides: according to the local farmers' regular application methods;3.Control: without any pest control methods applied.The damage and population of major lepidopteran pests(C.suppressalis and Cnaphalocrocis medinalis)in the different treated fields were investigated with manual inspection.Community structures of arthropods and damage of planthopper among the three treatments fields were studied with the suction sampler.The damage and population of major pests in paddy fields: In 2016,damage caused by C.suppressalis was more serious great in Hubei.The white panicles(1 tillers/one hundred hills)in the fields treated by combination of methods were significantly lower than the control(10 tillers/one hundred hills).The occurrence of C.suppressalis in the three treatments had no difference,however,all of them were lower than the economies threshold(2%-3%,Shu et al 2011).During the two growing seasons(2016 and 2017),likewise,the leaf-folded rate caused by C.medinalis in three treatments(from 0.2 to 2.3%)were significantly lower than the economies threshold(12.14%,Sun et al 2013),and there was no significant difference in leaf-folded rate between environmentally-friendly pests management field and chemical control fields.During the two-year observation period,the population density of the rice planthoppers in all the treated rice fields(Nilaparvata lugens:1.2-46.7 individuals/100 hills;Sogatella furcifera: 1.0-9.2 individuals/100 hills;Laodelphax striatellus: 1.1-16.7 individuals/100 hills)was significantly lower than the economies threshold(1000 individuals/100 hills in tiller stage;500 individuals/100 hills in booting stage,Hubei Plant Protection Station),there were no any difference in the most case among the three treatments.The environmentally-friendly pest management did not show the great advantage because the occurrence of main pests in the rice field were very low in 2016 and 2017.Impacts on arthropod diversity in the rice field: The diversity of arthropod community and the functional groups of natural enemies,especially parasitic natural enemies in the field treated by integration of different environment-friendly methods,were higher than those in the other two treatments,and the community similarity of field with integration of different environment-friendly methods was closer to the control.These results showed that the integration of different environment-friendly methods of pest management for rice pests control had positive effect on the eco-system of rice fields.In summary,the results of rotary ploughing,sexual pheromone traps,and attractants are as good as the expected.However,the use of solar frequency trembler grid lamp was need to be further verified on controlling lepidopterous pest in rice field.The environment-friendly pest management for rice pests had achieved the good control effect and been beneficial to the optimization of the ecological environment in paddy fields.Our results provides a good foundation for improving the level of environment friendly pest management in rice field of Hubei Province. |
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