Releases of Exotic Parasitoids of Bemisia tabaci in San Joaquin Valley, California

In 1991 Bemisia tabaci was reported in the southern San Joaquin Valley infesting crops outside of greenhouses for the first time. From 1994 to 1996, 24 species/ strains of imported aphelinids, primarily species of Eretmocerus, were released in urban and agricultural settings for control of this whitefly. Based on results of colonization and from other field and laboratory studies, several million individuals of the five highest ranked candidates were released from 1997 to 2000 into four citrus orchards in the southern San Joaquin Valley: Eretmocerus mundus, Eret. hayati, Eret. emiratus, Eret. sp. nr. emiratus, and Encarsia sophia. Citrus, in combination with surrounding weeds, aided in the initial establishment of several imported parasitoids. Although low numbers of parasitoids were found in citrus during this study, the high proportion of parasitism and the large number of trees showing parasitism would suggest that several hundred thousand parasitoids could be produced in each of our release sites during the fall. During surveys on weeds and cotton in 2002, all exotic parasitoids emerging from B. tabaci were Eret. mundus.