Submitted to: Program Review of Interagency Bemisia Classical Biocontrol Program in the U.S.
Publication Type: Book / Chapter
Publication Acceptance Date: 1/20/2006
Publication Date: 3/26/2008
Citation: Roltsch, W.J., Pickett, C.H., Simmons, G., Hoelmer, K.A. 2008. Habitat management for the establishment of Bemisia natural enemies. In: Gould, J., Hoelmer, K., Goolsby, J., editors. Classical Biological Control of Bemisia tabaci in the United States: a Review of Interagency Research and Implementation. Vol. 4, Progress in Biological Control, H.M.T. Hokkanen (series ed.). The Netherlands: Springer, Dordrecht. p. 243-257. Interpretive Summary: This book chapter, appearing within a book reviewing all aspects of a national multi-agency classical biological control program for sweetpotato whitefly in the U.S. during 1992-2002, summarizes field studies conducted in California desert agricultural regions aimed at improving whitefly management using conservation biological control methods. Conservation biological control works by manipulating the environment to favor natural enemies. Three strategies were employed: 1) multiple releases of large numbers of introduced natural enemies throughout the growing season, 2) planting a mixture of annual whitefly host plants to create short-term and permanent plantings as crop borders to provide year-long refuges to the natural enemies, and 3) promoting home gardens and enhancing backyard vegetation in urban settings as mini-refuges. This information will be useful to growers, farm advisors and other pest management specialists, and researchers who want to incorporate environmentally-friendly biological control options for management of whitefly. Wider adoption of conservation into whitefly management programs will reduce pesticide use by growers and thus reduce environmental contamination by pesticides. The technology developed in these demonstration projects should also foster development of similar programs for conservation biological control of other field crop pests.
Technical Abstract: During outbreaks of sweetpotato whitefly, Bemisia tabaci biotype B, in the 1990s in the southwestern United States, it was recognized that conservation biological control could play a key role in the establishment of newly introduced whitefly parasitoids. However, many Bemisia host plants in desert areas are short-lived annual species, therefore, parasitoids must locate hosts and reproduce on many different ephemeral plants. To promote successful establishment of new species of exotic parasitoids capable of surviving in the desert southwest, three strategies were employed and are reviewed in this book chapter: 1) multiple releases of large numbers of parasitoids throughout the growing season, 2) planting a mixture of annual host plants to create short-term and permanent refuge plantings in and near whitefly host crops, and 3) using home gardens and enhancing backyard vegetation in urban settings as refugia. Alfalfa cultivated as a food source for migrating birds in a national wildlife refuge was also used for parasitoid releases. Permanent insectaries provided the opportunity to observe parasitoid activity throughout the year over a wide range of weather. In contrast, summer-fall insectaries provided the opportunity to reliably mass produce parasitoids in large numbers at multiple locations. Although this conservation approach only functioned for a portion of the year (i.e., July-November), these gardens produced high numbers of parasitoids relative to whitefly.