Laboratory experiments were conducted to compare effects of cotton on the mortality and development of Bemisia argentifolii Bellows & Perring and Trialeurodes vaporariorum (Westwood) (Homoptera: Aleyrodidae), and on the key biological parameters of exotic parasitoid Eretmocerus mundus Mercet and on indigenous parasitoid Encarsia pergandiella Howard (Hymenoptera: Aphelinidae). Life table data revealed that host plant had a significant effect on most biological measurements across each whitefly genotype. Total preimaginal mortality showed that cotton was a significantly better host for B. argentifolii than for T. vaporariorum (35.2% vs 77.3%). Development to adult for B. argentifolii was significantly shorter (17.5 d) than for T. vaporariorum (23.2 d). Host plant had no significantly different effect on percentage female progeny. Preovipositional period and daily egg production were significantly affected. The parasitization and emergence rates of both parasitoids were significantly higher on B. argentifolii. But the differences between parasitism and emergence from whitefly species for E. pergandiella were less pronounced than by E. mundus. Eretmocerus mundus produced a significantly higher percentage of female progeny when parasitizing B. argentifolii (55.0%) than when parasitizing T. vaporariorum (25.0%). Whitefly species had no significant effect on progeny longevity of either parasitoids.