| Bemisia tabaci,one of the most harmful agricultural pests in the world,has the strong invasiveness and wide distribution characteristics,which had a great harmful to many crops.Among all the biotypes,MEAM1 and MED are most widely distributed and causing huge damage to the crops.At the same time,B.tabaci,as a vector of plant geminiviruses,carries a large number of plant geminiviruses,which also binged devastating damage to crops.For the moment,using chemical pesticides was the main control method to control it,which has caused the highly insecticide resistance to a variety of chemical agents.This study systematically monitored the distribution of MEAM1 and MED in many regions in China,the carrying status of three plant geminiviruses such as TYLCV,To CV,and CCYV and the insecticide resistance of B.tabaci in different ages.The results were as follows:1.The distribution of B.tabaci MEAM1 biotype and MED biotype in ChinaIn 2019,a total of 86 B.tabaci populations were collected from multiple regions across China.Among them,78 B.tabaci populations were identified for MED biotypes and 7populations were mixed for both two biotypes.Among them,there were 4 populations dominated by the MED biotype and there were 2 populations that the rare of the MED biotype and the MEAM1 biotype were 50%.In addition,only one populations was dominated for the MEAM1.Among all identified populations,there was only one population with MEAM1 biotype accounting for 100%of the identified samples.The MED biotype accounts for 98%of all populations,which has become the main population in China.2.The situation of TYLCV,To CV and CCYV for the field population of B.tabaci in ChinaIn 2019,the results of identification of the TYLCV for 7 various regions of field B.tabaci in China,which was collected for the tomato host,showed that all of the B.tabaci were carried TYLCV and the virulence rate of TYLCV in 4 populations was 100%.The other 3 populations had different carrying rate of TYLCV.In addition,the results of identification of the To CV for 7 various regions field B.tabaci in China showed that the rate of carried To CV was varying for different regions.One of the populations has a carrying rate of 100%.The population with a carrying rate of more than 50%accounted for 43%.The population with a carrying rate of less than 50%accounted for 57%.In 2019,27 field B.tabaci populations in 14 regions,which were collected from melon host,were tested for CCYV carrying rate.The results showed that the 27 populations were carried virus,which was accounting for 85%and the 100%carrying rate accounted for 15%,the populations with a virulent rate higher than 50%and less than 100%was accounted for 33%The populations carrying CCYV but with a virulent rate of less than 50%accounted for 37%,and the test populations that did not carry CCYV accounted for 15%of all identified populations.The monitoring results showed that the three plant geminiviruses,including TYLCV,To CV,and CCYV,were spreading in China.3.The insecticide resistance of B.tabaci in China.The insecticide resistance monitoring results of the field whitefly in 2019 showed that the insecticides（abamectin,flupyradifurone,and cyantraniliprole）have relatively high virulence to whitefly adults in the field and the insecticide resistance fold were not more than3 times for all of the tested field whiteflies,which indicated that it were sensitive for the three insecticides.The virulence effect of cyantraniliprole on the nymphs of B.tabaci in the field is slightly higher than that of spirotetramat and pyriproxyfen.The highest LC50was4.96 mg·L-1.The monitoring results of the field whitefly eggs indicated that the virulence effect of cyantraniliprole was slightly higher than that of spirotetramat.Among them,the LC50value of the Yuncheng population in Shanxi was 58.23 mg·L-1and the insecticide resistance level was the highest,which was higher and a huge increase in 2018.In addition,the LC50values in other regions were all less than 20 mg·L-1. |
