Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/20/2000
Publication Date: 12/1/2000
Citation: Mcauslane, H.J., Simmons, A.M., Jackson, D.M. 2000. Parasitism of silverleaf whitefly, bemisia argentifolii, on collard with reduced or normal leaf wax. Florida Entomologist. 83:428-437. Interpretive Summary: The silverleaf whitefly is an important insect pest of collard that must be controlled with conventional insecticides. We are studying alternative methods of control that do not use insecticides. Two alternative methods which we are studying are using collards that are resistant to whitefly, and biological control using parasitic wasps that attack the whiteflies. The leaves of the resistant collards that we are studying have reduced leaf-wax rather than the waxy leaves that most collards have. Plant characteristics such as leaf type and texture can effect the efficiency with which the parasitic wasps search for and attack whiteflies. These experiments showed that the reduced leaf-wax type of collard had no adverse effect on the parasites, indicating that the two control methods could be effectively combined for whitefly control.
Technical Abstract: Collard, Brassica oleracea var. acephala L., cultivars with reduced leaf wax (i.e., glossy phenotypes) possess ovipositional antixenosic resistance to Bemisia argentifolii. We investigated parasitism by two parasitoids of B. argentifolii reared on two phenotypes of the collard cultivar 'Green Glaze', differing in amount of leaf wax. When Eretmocerus sp. parasitoids were either given a choice or not given a choice between parasitizing whitefly nymphs on glossy and normal-wax collard, there were no significant differences in the number of parasitized nymphs, nor in the proportion of whiteflies parasitized, on the two plant phenotypes. However, 4.5 times more Encarsia pergandiella emerged on glossy than on normal-wax plants, and the proportion of whiteflies parasitized on glossy collard was more than double that on normal-wax collard in a choice test. In a no-choice test, more than twice as many E. pergandiella emerged from whiteflies on glossy collard than on normal-wax collard. In addition, the proportion of whiteflies parasitized was significantly higher on glossy collard than on normal-wax collard in one of the two experimental trials. Time to 50% emergence for whiteflies and both species of parasitoids did not differ on the two collard types. We concluded that management of B. argentifolii populations can be improved on collard, and probably other B. oleracea vegetables, through the use of reduced leaf wax cultivars with antixenosic resistance to B. argentifolii and have no detrimental effects, on important whitefly natural enemies.