Impact of cadmium mediated artificial diet on growth and nutritional indices of Spodoptera litura F (Lepidoptera: Noctuidae)

The studies were conducted in the Department of Environmental Science, Dr YS Parmar University of Horticulture and Forestry, Nauni, Solan, HP during 2012–2013 on tobacco caterpillar (Spodoptera litura F). The artificial diet mixed with various concentrations of cadmium was offered continuously to the larvae of the insect for three generations. Maximum growth rate was attained at lower doses (1 to 5 mg/kg) and minimum at higher doses (30 to 40 mg/kg). The consumption index of all the larval instars at higher doses (30 mg and 40 mg/kg) was less than control. Maximum approximate digestibility (71.62%) of second instar larva was recorded with 1 mg Cd/kg which decreased in successive instars and digested approximately to 27.74 per cent in sixth instar. Maximum efficiency of conversion of ingested food (36.32%) of second instar larva was in the same treatment which decreased in successive instars and efficiency of conversion of ingested food was 17.59 per cent in sixth instar. Maximum efficiency of conversion of digested food (51.66%) of second instar larva was also with 1 mg Cd/kg which increased in successive instars (68.29% in sixth instar). Hence it can be concluded that growth rate and various nutritional indices (consumption index, approximate digestibility, efficiency of conservation of ingested food and efficiency of conservation of digested food) were lower at higher doses in three successive generations as compared to control and lower doses under study.