Release and Recovery of Exotic Natural Enemies of Bemisia tabaci (Biotype “B”) ((Hemiptera: Aleyrodidae) in Imperial Valley, California

Numerous methods of release were used to establish parasitoids of Bemisia tabaci in the deserts of southern California. Despite the release of a large number of species, only a few species became well established. Because of the intensive effort put forth toward establishing new species it is probable that the failure of some species to establish was due to their being poorly adapted to this desert agricultural region. The results presented here are convincing evidence that establishment by Eretmocerus emiratus and Eret. sp. nr. emiratus (M95104 and M96076) has occurred at numerous sites within the Imperial Valley and that population growth and dispersal are continuing. The climate in the countries of origin of these populations in the United Arab Emirates and Ethiopia closely matches the climate in southwestern US desert valleys. It is likely, however, that their populations have yet to reach equilibrium in Imperial Valley. Data suggest that the establishment process of those exotic Eretmocerus that successfully established has been dynamic, involving a consistent increase in exotic parasitoid populations through 2000 on numerous host plants of Bemisia, and a steep decline in 2001 followed by a population rebound in 2002. Data collected as recently as 2004 indicate that exotic Eretmocerus populations and Encarsia sophia from Multan, Pakistan, continue to represent a significant proportion of the Bemisia parasitoid community.