Study On The Overwintering Adult Host, Occurrence And Distribution Of The Rice Water Weevil (Lissorhoptrus Oryzophilus) In Dongning City

The rice water weevil Lissorhoptrus oryzophilus Kusche is a quarantinable pest in China,which is extremely harmful to rice and can reduce rice yield by about 30% under normal conditions.In this study,after the identification of rice water weevil adults in Dongning City,the host plant species of rice water weevil adults,as well as the field distribution pattern and occurrence trend of rice water weevil adults were investigated,so as to provide theoretical basis for controlling the population quantity of rice water weevil and reducing the harm of rice water weevil.The results are as follows:1.The overwintering adults collected from Dongning city were identified as rice water weevil adults through morphological and molecular identification.2.By investigating the host plant species of overwintering adults of rice water weevil,the feeding plants of rice water weevil were 15 species of 4 families.11 species of gramineae;2species in sedge family;Anaraceae and Araceae 1 species each.Four rice varieties longdao 5,Longdao 18,Kengjing 8,Songjing 9,and three wild hosts Echinochloa crusgalli(L.)Beauv.,Setaria viridis(L.)Beauv,and Northeast Jianmainiang were tested Alopecurus mandshuricus Litw.The results showed that the overwintering adults of rice water weevil had significant difference in feeding selectivity to different host plants,among which the feeding selectivity to Kengjing 8 and Barnyard grass was the highest.The "Y" olfactory instrument was used to determine the olfactory selectivity of the overwintering adults of rice water weevil to four rice varieties and three wild hosts.The results showed that the overwintering adults of rice water weevil had the highest olfactory selectivity to rice variety Kenjing 8 and wild host Barngrass.These results indicate that the overwintering adults of rice water weevil have a preference for different host plants.3.The trend of the spread of rice water weevil from the ridges of the wintering site to the field was investigated.The results showed that the farther away the occurrence of rice water weevil from the field to the wintering site,the smaller the distribution base was,and the long-distance spreading ability of rice water weevil was poor.The overwintering adults of rice water weevil occurred in paddy fields on both sides of the road,and the population density and occurrence area of the sunny side(south side)were larger than those of the shady side(north side).4.The adults of rice water weevil can spread along irrigation water,but the distance is not too far.Flight diffusion was not the main cause of local diffusion of rice water weeperia.5.Taylor's power rule and Iwao regression analysis were used to integrate and analyze the field distribution data of overwintering adults of rice water weevil in six paddy fields of Yijie Village,Dachengzi Village,Dongsui Village and Sanchakou Village.The results showed that the overwintering adults of rice water weevil showed negative binomial aggregation distribution with common K value in the field.The aggregation intensity increased with the increase of population density.