Submitted to: Program Review of Interagency Bemisia Classical Biocontrol Program in the U.S.
Publication Type: Book / Chapter
Publication Acceptance Date: 12/15/2005
Publication Date: 3/26/2008
Citation: Simmons, G., Hoelmer, K.A., Natwick, E. 2008. Integrating parasitoid releases with traditional control methodologies: experience in the spring melon production system in the southwestern USA. In: Gould, J., Hoelmer, K., Goolsby, J., editors. Program Review of Interagency Bemisia Classical Biocontrol Program in the U.S.A. Vol. 4 Progress in Biological Control, Hokkanen, H.M.T., series editor. The Netherlands: Springer, Dordrecht. p.259-285. Interpretive Summary: A multi-agency demonstration project on augmentative biological control of the sweetpotato whitefly was conducted from 1994 through 2000 using releases of introduced species of Eretmocerus parasites [there is no common name for these] in spring melons in the Imperial Valley of California. 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 seven years of field studies and commercial-scale demonstrations of augmentative releases of whitefly parasitoids. Reduction of whitefly populations by augmentative releases was comparable to reductions from using pyrethroid insecticides. We discuss possibilities for technology transfer, limitations of augmentative releases as a management technique, and prospects for future use of augmentative control strategies for control of sweetpotato whitefly in desert agroecosystems. 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. Adoption of augmentative biocontrol releases into whitefly management programs will reduce pesticide use by growers and thus reduce environmental contamination by pesticides. The technology developed in these demonstration projects will also foster development of similar programs for augmentative biological control of other field crop pests.
Technical Abstract: Early during the outbreaks of sweetpotato whitefly, Bemisia tabaci biotype B, in the 1990s in the southwestern United States, it was recognized that efforts needed to be made to integrate parasitoid releases with existing chemical control strategies as part of a program to import and establish new exotic species of whitefly parasitoids. Areas with winter and early spring vegetable and melon production experienced the most severe infestations with whitefly persisting through most of the year. Because high rates of parasitism of Bemisia by native parasitoids were observed on certain crops near the end of the production cycle, we postulated that inoculating susceptible crops with parasitoids early in the season would lead to earlier higher rates of parasitism and provide greater natural control, reducing need for extensive pesticide applications. This strategy was also expected to increase the likelihood of permanent establishment of the newly imported species of parasitoids by making use of spring melon fields as large field insectaries. The project used the mass-production systems developed for the importation and establishment of new species of whitefly parasitoids for the classical biological control program to provide the large numbers of parasitoids needed for replicated field scale releases. Our initial studies showed that the exotic species produced greater numbers of progeny and achieved higher levels of parasitism than the native Eretmocerus eremicus, so continued work on demonstration projects was performed only with exotic species of Eretmocerus. In this book chapter, we review conventional and IPM methods of pest control in whitefly susceptible crops, obstacles and opportunities for integrating parasitoids; we describe our research in implementing and integrating parasitoid releases in spring melons with existing technology, and we discuss the remaining knowledge gaps needed for full implementation of an augmentative release strategy in these crops.