Study On The Occurrence And Control Technology Of Lissorhoptrus Oryzophilus Kuschel In Guangdong Province

Rice water weevil(Lissorhoptrus oryzqphilus Kuschel)(Coleoptera:Curculionidae)is a worldwide quarantine insect pest.The insect is listed as one of the most threatening100 alien invasive organisms by IUCN(International Union for Conservation of Nature),and it is also a quarantine pest on rice in China.At present,rice water weevil has been distributed in 24 provinces in China.The latest invasion of the pest was in Pingyuan County and Wuhua County of Meizhou City in 2017,which posed a great potential threat to rice production in Guangdong Province.In order to find out the occurrence and distribution,damage degree,life history,overwintering transition host and other occurrence rules and biological characteristics of rice weevil in the double cropping rice planting ecological area after the new invasion of rice weevil in Guangdong,and to explore the suitable new prevention and control technology of rice weevil in this area,his study studied the life history and overwintering law of rice weevil in Guangdong through field investigation,shroud observation experiment and ovarian anatomy.The overwintering transition hosts were identified by molecular detection of intestinal contents of rice water weevil;SCAR technology was used to detect the main natural enemies of rice water weevil;field experiments were conducted to screen out the suitable pesticide combinations for UAV spraying with good control effect.The results are as follows:1.The occurrence distribution and damage degree of rice water weevil in Guangdong epidemic area were basically clarified.At present,the epidemic situation of rice weevil in Guangdong Province only occurred in Wuhua County and Pingyuan County of Meizhou City.A survey of rice weevil was carried out in 28 towns of Wuhua and Pingyuan counties in Meizhou City,Guangdong Province.The survey results showed that the occurrence of rice weevil in Wuhua and Pingyuan counties in Meizhou City,Guangdong Province was low,and all the towns surveyed were mild.2.The life history of rice weevil in Guangdong double cropping rice area was revealed clearly.There are two generations of rice water weevil in double cropping rice area of Guangdong Province in one year,and its growth period is highly coincident with that of rice.After the seedlings were transplanted to the field in mid-late March,the overwintering generation of rice water weevil began to migrate from the overwintering field to the field,and reached the peak in early April.The overwintering adults began to lay eggs in early April.The larvae began to hatch in mid-April and reached the peak in late April.By the early May,the mature larvae began to pupate,and the first generation of adults began to emerge in the middle and late May,with the final stage of early June.The first generation adults will move into the field after transplanting late rice in late July.The second generation larvae began to hatch in early August.The mature larvae began to pupate in late August,and the second generation of adults began to emerge in early and middle September.The adults were finally found in late September.3.The species of transitional host plants and predatory natural enemy groups of rice water weevil in Guangdong were preliminarily clarified.The wintering sites of rice weevil in Guangdong are different from those in other regions,mainly in swamps where water and grass are dense.The pattern of wintering sites is rice field-transitional zone(grassland)-wintering sites(abundant water and grass,moist soil).And overwintering rice water weevil has reproductive diapause phenomenon,ovarian development grade is0.At the same time,through PCR diagnosis technology,it was detected that the intestinal tract of overwintering rice water weevil mainly contained rice DNA and some individuals contained Leersia hexandra Swartz DNA,but all did not detect Paspalum distichum L.DNA,indicating that some overwintering rice water weevil would feed on Leersia hexandra Swartz to supplement energy and would not feed on Paspalum distichum L..PCR diagnosis confirmed that Pardosa laura prey on rice water weevil.4.A new formulation of pesticide in UAV was screened and successfully applied to the aerial defense of rice water weevil.200 g/L chlorantraniliprole suspension 10 m L/666.7 m~2+25%thiamethoxam water dispersible granule 6 g/666.7 m~2 had the best control effect,the leaf retention rate reached 87.99%,and the larvae control effect was87.61%.The control effect was good and suitable for production and use.