The whitefly (Trialeurodes vaporariorum Westwood), a polyphagous insect, attacking many different crop and ornamental plant species can be a most serious problem in greenhouses. Fitness of the parasitoid (Encarsia formosa Gahan) was studied when the whitefly host reared on four different host plants under laboratory conditions. The plants tested were cucumber (Cucumis sativus L.), tomato (Lycopersicum esculentun Mill), bean (Phaseolus vulgaris L.) and sweet pepper (Capsicum annum L.). The results indicated that the head width as well as parasitoid immature mortality were not significantly affected. Host plants significantly influenced development time up to adult eclosion for E. formosa. Parasitoids reached the adult stage faster on bean than on others. Fecundity of E. formosa reared in whitefly on different host plants was significantly different. Parasitoids were observed to be more fecund on bean than on other plants. The results indicated that life history parameters of parasitoid, E. formosa, are influenced by host plants. The effects were complex but generally interpretable in terms of host whitefly quality variation among host plants used as food by the whiteflies during their development.
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