Age-Specific Interaction Between the Greenhouse Whitefly and Encarsia formosa: Influence of the Parasite on Host Development

The life cycle of the greenhouse whitefly, Trialeurodes vaporariorum</it> Westwood, consists of an egg stage, 4 nymphal instars, and an adult. It is convenient to divide the 4th stage into 3 substages: the “early” 4th instar, the transitional substage, and the unemerged pharate adult. The developmental rate of 2nd, 3rd, and “early” 4th whitefly nymphal instars, parasitized by Encarsia formosa</it> Gahan, does not differ significantly from that of unparasitized hosts. However, developing parasites arrest whitefly development during the transitional and pharate adult substages of the 4th stage.