Study On Rice Diseases And Pests Control Efficiency By Applying Microbiological Agents And Spiders

We conducted experiments on biocontrol of rice diseases and pests in the modern agriculture demonstration park,which belongs to Jiangsu kesheng group co.,LTD.(Jianhu,Jiangsu)in 2018 and the rice paddy base belongs to Jiangxi xinghuo agriculture and forestry science and technology development co.,LTD.(Yichun,Jiangxi)in 2019,respectively.We released euryphagic predator spiders to control the populations of main pests and applying beneficial microbial agents to prevent main diseases in the biocontrol fields(for short BCF),while routine chemical germicides and pesticides were applied to control the diseases and pests in the chemocontrol fields(for short CCF).Our results showed that conbination of"beneficial microbials preventing diseases"and"spiders controlling pests"is effective in managing diseases and pests of the rice.Without using any pesticides and germicides,grain outputs of the three rice varieties from the biocontrol paddies reached or above 98%of those reported by the China Rice Data Center,in which the rice yields are based on routine chemical control of the diseases and pests.1.The benificial microbial agent"Ningdun"is effective in controlling the occurrence and prevalence of rice diseases.The main rice diseases Pyricularia grisea,Thanatephorus cucumeris and Ustilaginoidea oryzae occurred in both of BCF and CCF in the Jianhu experimental field.Among them,the occurrence rate of U.oryzae in BCF was less than 4%,almost the same as that in CCF.However,P.grisea and T.cucumeris were more serious in CCF than those in BCF.In the peak period,the average occurrence rate of P.grisea and T.cucumeris in CCF reached or above 5.8%,while that in BCF was less than 5.8%,and the difference between BCF and CCf was significant.In Yichun experimental field,P.grisea and T.cucumeris also occurred in both of BCF and CCF,but have a lower occurrence rate of less than 2%,and there is no significant difference between BCF and CCF.Our study testified that applying the benificial microbial agent"Ningdun"can prevent the spread of main rice diseases.2.Population sizes of the spiders Lycosidae,Linyhiidae,Theridiidae in BCF were significantly bigger than those in CCF.Due to the applying of chemical pesticides in CCF,a large number of spiders,together with their prey insects were killed.Meanwhile,reproductive capacity of the spiders in CCF decreased because of the insufficiency of prey insects,resulting in less offspring than those in BCF.And the spider populations were affected even more serious after repeated application of the chemicals.However,without applying chemical pesticides and gemicides,spiders in BCF can prey and reproduced just like they do in the naturally fields,the spider population increased quickly and remarkbly,which ensured the effective control on the rice pests and thus prevent the damage caused by rice pests.3.There was significant difference in the number of rice planthoppers while no significant difference in the number of other pests between BCF and CCF.The rice planthopper was the major pest in both of BCF and CCF.In August and September,the number of paddy planthoppers was 130～300 Ind./m~2 in BCFwhile 30～50 Ind./m~2 in CCF.There was significant difference in quantity of the planthopper but not other pests between BCF and CCF.It can be seen that the applying chemical pesticides has a great effect on controlling the population size of the rice planthoppers in CCF.The population sice of the rice planthopper growed rapidly in BCF,where no chemical pesticides were applied.Thus the rice planthopper is the key species for biocontrol of rice pests.4.The natural enemy--euryphagic predatory spiders--effectively controlled the populations of main rice pests.The ratio of spider to pest showed that the average maximum density of the spider assemblage in BCF was 109.7 Ind./m~2,and that of the rice insects was 278.6 Ind./m~2.The ratio of spider to pest maintained below 1︰4.4 throughout the rice growing season in BCF of the Jianhu experimental field.In CCF,the average maximum density of the spider assemblege was 23.6 Ind./m~2,and that of the pests was36.1 Ind./m~2.The ratio of spider to pest were maintained below 1︰2.4.However,in the Yichun experimental field,the average maximum density of the spiders was 127.1 Ind./m~2,and that of the pests was 124 Ind./m~2 in BCF.The ratio of spider to pest of the whole rice growing season was generally maintained at about 1︰1.1.The average maximum density of the spiders was 56.7 Ind./m~2,and that of the rice pests was 53 Ind./m~2 in CCF and the ratio of spider to pest was also around 1︰1.1.Though the pest amount in BCF is higher than that in CCF,the pest populations were still under control of the predatory spiders throughout the rice growing period.The populations of both spiders and pests maintained at very low level.5.The conbination of beneficial microbials and spiders has good effect on controlling rice diseases and pests,and thus acheived better economic and ecological benifits for rice culture.The average yield of Nanjing 5055 and Nanjing 9108 in BCF were9,053.03Kg/hm~2 and 9,681.31Kg/hm~2,respectively,and 9,180.83Kg/hm~2 for Huaidao 5 in CCF in Jianhu experimental field.The average yield of Yexiangyoumingyuesimiao in BCF was 8,638.87Kg/hm~2 and that of Nongxiangyouhuazhan in CCF was 9852.63Kg/hm~2 in Yichun experimental field.The rice yields of the rice varieties,including in BCF and CCF,all reached or above 98%of those reported by the China Rice Data Center.The estimated economic profit in BCF and CCF were 86,581.2Yuan/hm~2 of and 29,258.6Yuan/hm~2,respectively.In addition,without using chemical pesticides and gemicides in the paddy field,the ecological benefit is ensured for the rice culture in BCF.