Abstract:In order to evaluate the resistance risk of Helicoverpa armigera to methoxyfenozide, H.armigera was used to select for resistance to methoxyfenozide in the laboratory. After 29 times of selection one time one generation with methoxyfenozide during 33 generations, the population developed 32.99-fold resistance to the insecticide. Realized heritability (h2) of resistance in different selection stages was evaluated based on the Tabashnik’s methods. The results suggested that h2 for the entire selection experiment was 0.0830. h2 to methoxyfenozide in the early, middle and latter selection stages were 0.0715, 0.0768 and 0.0947 respectively. Assuming that slope was 2.0 (δp=0.5), and the h2 was half of indoor estimation value, it required 34.48 and 27.40 generations of H.armigera to obtain 10-fold increase of methoxyfenozide in LC50 under selection pressure at 80% and 90% mortality for each generation of selection. The number of generations required for 10-fold increase would be even more in field due to the changes in allele frequency and environmental variation or both.