The Study On Occurrence Regularity And Control Techniques Of Rice Water Weevil In Shaanxi Province

The rice water weevil(Lissorbqptrus oryzqphilus)is an important pest of rice worldwide,and also a quarantine pest in China.In recent years,it was prevalent in the south of Shaanxi province and caused a severe yield loss of ricecrop.The studies have shown that the generation,evolution and habits of the rice water weevil populations have differences in various areas,which were influenced by geographical environment and cultivation custom.Therefore it is significant to study the evolution of the populations,the optimal control period and the effective prevention and control measures in order to control the damage of the rice water weevil and secured rice yield without losses effectively in Shaanxi province.In this study the population dynamics and fluctuation,life history,overwintering sites and its host plant of rice water weevil are investigated by follow-up survey and sample analyzing.While the control effects against the larva and adult of rice water weevil were studied in field test.The results are as follows:1.Rice water weevil has one generation a year in rice producing regions of Shaanxi province,and overwinters by adult.The overwintering adults appear in the middle and late March(temperature varies from 10~15?).The activity of larva reaches their peak in late May and earlyJune,and it was the key period in chemical control.The developmental duration of each stage of rice water weevil is 15~20 days later in mountainous regions than that in flat plain.2.Overwintering adults lives in the soil 0~5cm underground.50.9% of the overwintering adults live in the ditches along the rice fields,46.89% in the ridge,2.21% in hills and 0% in wasteland.The rice water weevil adults begin to overwinter in the ditches moving from the ridge in early autumn.3.The rice water weevil infected host plant species of 9 families,31 species in Shaanxi,including Gramineous,Cyperaceae,Alismataceae,Juncaceae,Commelinaceae,Araceae,Potamogetonaceae,Compositae,Polygonaceae crops.It was found that the rice water weevil damage Gramineae and Cyperaceae crop pest base largely,other sporadic crops was discoveried.4.Field experiment showed that 20% adult control Ding Liuke Budweiser EC,10% abamectin flutolanil suspension and 20%-three of Xin EC on rice water weevil has good control effect,and the duration is longer,in the tested dose,control effect of 15 d after administration respectively as of 80.60%,79.40% and 73.40%;in the control larvae after transplanting 16~22 days,the relative control effect was 100%,with the best insecticidal effect of phoxim granules.This study identified the rice water weevil generation and the insect occurrence period of rice in Shaanxi province region,which screened for effective prevention and treatment of adult and larvae of new pesticides.Meanwhile,it puts forward the comprehensive management of water rice weevil measures,and provide scientific basis for the prevention and control of Shaanxi province rice water weevil.