Fourth International Bemisia Workshop International Whitefly Genomics Workshop
Establishment and Impact of Exotic Aphelinid Parasitoids in Arizona: A Life Table Approach
USDA-ARS, Arid-Land Agricultural Research Center, Maricopa, AZ, USA
A large multi-institutional, interagency classical biological control program was initiated in the early 1990s to combat the invasion of the B biotype of Bemisia tabaci into the USA. This large program was successful in the discovery, importation, rearing and release of more than 30 species/strains of aphelinid parasitoids (primarily Eretmocerus and Encarsia) from around the world into multiple states. Establishment of several species in each targeted state has been documented. However, the impact of these establishments and the overall biological control program has been poorly documented. From 1996 through the present in situ life tables have been constructed for B. tabaci in cotton and several other important host crops and plants in central Arizona. In the late 1990’s, and prior to the documented establishment of two exotic aphelinids in Arizona in the early 2000’s (Er. nr. emiratus and En. sophia), parasitism contributed a consistently small amount of mortality to B. tabaci in cotton fields. Subsequent life tables in cotton and a number of other host crops and plants showed that levels of parasitism were generally enhanced within a multi-crop system and that these increased levels of mortality coincided with the documented establishment of two exotic species. However, life table studies in cotton over the past few years have been inconclusive relative to impact, with levels of mortality from parasitism fluctuating widely between low and moderate. Further life table analyses (key factors, density dependence) are planned and should help to interpret and quantify the potential impact of these introductions on whitefly population dynamics.
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