REALIZED HERITABILITY OF RESISTANCE TO DICROTOPHOS IN GREENHOUSE-WHITEFLY

Realized heritability (h2) of resistance to dicrotophos in greenhouse whitefly, Trialeurodes vaporariorum Westwood, was estimated from a laboratory selection experiment. Five generations of selection increased the LC50 approximately 13-fold. Estimated h2 of resistance to dicrotophos was 0.40 when calculated with the method of Tabashnik (1992) and 0.35 with the method of Tanaka & Noppun (1989). These results suggest that 35 to 40% of the total phenotypic variation in resistance was caused by additive genetic variation. For thirteen previously reported estimates of h2 of insecticide resistance in other insect pests, the mean was 0.29. The relatively high h2 of dicrotophos resistance for T. vaporariorum is consistent with rapid resistance development in field populations.