Parasitic Preference of Encarsia formosa on Bemisia tabaci and Trialeurodes vaprorariorum

Preference of the Encarsia formosa for two species of whitefly,Bemisia tabaci and Trialeurodes vaprorariorum,and its parasitic potentials to nymph of B.tabaci infesting different crops were assessed in the laboratory.Results showed that when tobacco whitefly coexisited with greenhouse whitefly,the parasitoid preferred to parasitize T.vaprorariorum over B.tabaci,and they produced significantly higher parasitism rate on greenhouse whitefly than on tobacco whitefly.Its parasitism rates were affected by host plants.Encarsia formosa parasitized more nymph of tobacco whitefly on tobacco than on other three crops.There were significant difference in parasitism rate between four tested crops,and its preference order for the four crops was as follow:tabacco cabbage cotton cucumber.