Effects Of Different Foods On Development Of Serangium Japanicum And The Control Effect Of Its Joint Release With Encarsia Formosa On Bemisia Tabaci

Bemisia tabaci has a wide host range and is one of the important pests in agriculture.In recent years,due to its strong insecticide resistance and "3R" problem,more and more attention has been paid to controlling the occurrence of Bemisia tabaci by biological control methods.As one of the important natural enemies of Bemisia tabaci,Encarsia formosa has been commercialized.Serangium japonicum is one of the dominant predators of Bemisia tabaci.In this paper,the effects of different foods on the growth and development of Serangium japonicum were studied firstly,and then the control effect of the combined release of two natural enemies against Bemisia tabaci was studied under greenhouse conditions.The main results are as follows:1.Effects of different foods on the growth and development of Serangium japonicum.S.japonicum can not complete its growth and development when feeding on parasitized nymphs by E.formosa.The survival rate was only 2.2% when third instar larvae fed the parasitized nymphs and 35.5% when S.japonicum first instar larvae fed Corcyra cephalonica eggs.The survival rate was 59.1% when third instar larvae preyed on Corcyra cephalonica eggs.S.japonicum did not lay eggs when feeding Corcyra cephalonica eggs or parasitized nymphs.The fresh weight of the ladybird adult was significantly lower than that of feeding whitefly nymphs.2.Effects of feeding experience on larval selectivity of S.japonica.The first and second larvae fed on nymphs of B.tabaci,and third instar larvae fed on parasitized nymphs.The fourth instar larvae obviously preferred to feed on B.tabaci nymphs.3.Control efficiency of Bemisia tabaci by the joint release of S.japonicum and E.formosa.The control efficiencies of five pairs S.japonicum treatment against B.tabaci adults and nymphs were 5%-69% and 5%-35%,respectively;the control efficiencies of ten pairs S.japonicum against B.tabaci adults and nymphs were 28%-74% and 15%-81%,respectively;the control efficiencies of ten E.formosa against B.tabaci adults and nymphs were 38%-85% and 12%-71%,respectively;the control efficiencies of twenty E.formosa against B.tabaci adults and nymphs were 10%-68% and 30%-56%,respectively.The control efficiencies of the combination of five pairs S.japonicum and ten E.formosa against the whitefly adults and nymphs were 5%-66% and 3%-61%,respectively;the control efficiencies of the combination of ten pairs S.japonicum and twenty E.formosa were 20%-70% and 11%-60%,respectively.