Demographic study of imidacloprid-resistant Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae) fed on transgenic and commercial potato cultivars

Impacts of transgenic and non-transgenic potato (Solanum tuberosum L.) plants containing more than one insecticidal gene on life table parameters of an imidacloprid-resistant Colorado potato beetle (CPB) colony, Leptinotarsa decemlineata, were studied under laboratory conditions. The life table parameters of the CPB colony on both commercial potato cultivars Agria and Lady Olympia and their transgenic counterparts were studied utilizing two methods: individually reared and group-reared to understand full potential of this destructive pest. All tested CPB larvae and adults on transgenic potato plants died before obtaining any results for the two-sex life table studies. The life table parameters were calculated using non-transgenic plants. The intrinsic rate of increase (r), the finite rate of increase (lambda), the net reproductive rate (R-0) and the mean generation time (T) were calculated 0.15 day(-1), 1.16 day(-1), 233.81 eggs/female and 37.43 days on Lady Olympia respectively. The CPBs, reared on cultivar Agria, had significantly lower values of r, lambda and R-0 except T (0.12 day(-1), 1.13 day(-1), 120.81 eggs/female and 39.75 days) respectively. The net reproductive rate (R-0) (204.31 eggs/female) and the mean generation time (T) 43.86 days of CPB were longer on Lady Olympia than on Agria when reared in groups. All these results indicate that the non-transgenic potato cultivar, Lady Olympia is a more susceptible host for CPB than the potato cultivar Agria and the transgenic potato cultivars exhibit significant toxicity and could be useful in control of imidacloprid-resistant CPB population.