Composition And Occurrence Dynamics Of Agromyzid Leafminers And Its Parasitic Wasps In Beijing Area

Agromyzid leafminers are important pests of tiny pest which feeding on vegetables and commercial flowers.The invasion of alien leafminers has increased the damage in China and parasitoid wasp would be the first choice as the method of biocontrols.In recent years,as the increasing of invasion times,changing of the crop layout,cropping system and climate,the occurrence and damage of the leafminers significantly changes.In this study,the composition and dynamics of the leafminers and their parasitoid were investigated in Beijing area,which results could explain the reason of diversification of temporal distribution of leafminers and their natural enemies,providing the suggestion for control of agromyzid leafminers in the future.1.Species composition,dynamics of leafminers and their host plants in Beijing.Five leafminer species were found in the field survey in Beijing,including local species Chromatomyia horticola(Goureau),Liriomyza chinensis Kato and alien species Liriomyza sativae Blanchard Liriomyza huidobrensis(Blanchard)and Liriomyza bryoniae(Kaltenbach).C.horticola and L.sativae are two dominant species.C.horticola occurred at spring and autumn,L.sativae occurred at sumer and autumn,and both species caused serious damage between summer and autumn.L.chinensis,a moderate damaged pest,mainly occurred in summer.L.bryoniae occasionally occurred and L.huidobrensis only two individuals were found.Field survey of host plants indicated that C.horticola has most widespread host range,including 8 families and 23 species.L.sativae prefers 8 familes and 16 species of host.L.bryoniae has less host plants.2.Species composition,dynamics of parasitoid waspsTwenty-seven species of parasitoid wasps were found in Beijing which belong to Eulophidae,Pteromalidae,Braconidae and Cynipidae.Most species were found in Eulophidae: 9 genera and 18 species,less species were found in Pteromalidae,Braconidae and Cynipidae: 2 genera and 3 species,2genera and 5 species,1 genus and 1 species.22 species belong to 4 families were feeding on C.horticola,16 species belong to 4 families were feeding on Liriomyza sativae,8 species belong to 3families were feeding on L.chinensis.Most of the species occurred in cool seasons and D.isaea served as the dominant species in this period.In the summer,the species of parasitoid decreased and Neochrysocharis formosa and Closterocerus lyonetiae would be the dominant species.Parasitoids prefer different leafminer host plants.3.Genetic differentiation and dynamics of N.formosa complex groupThe result of genetic differentiation and dynamics of N.formosa indicated that at least 3 cryptic species existed in China.Based on the COI gene and ITS2 gene,there were 2 cryptic species in Beijing and one belongs to the arrhenotokous strain,and the other was thelytokous strain,belonging to different species.Arrhenotokous strain and thelytokous strain coexisted in Beijing and thelytokous strain were dominant.Thelytokous strain adapted the hot season compare to the arrhenotokous strain,and theirpreference of the host was slightly different.N.formosa could be good resources to control the leafminers.Our results systematically elucidated the species composition and dynamics of leafminers and their parasitoids and explain why the change occur.Based on the results,we provide suggestions on the future control of leafminers,eg.Dominant wasps rearing and releasing,cropping system modification and ecological management.