Biology of Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae) and their feeding potential on parthenium and sunflower.
Studies on biology of Zygogramma bicolorata Pallister on Parthenium hysterophorus (Linnaeus) showed that the Mexican beetle laid small, oblong, elongated, light yellow eggs on leaf surface and lid of the container under the laboratory condition. The average incubation period and hatching percentage were, 4.40±0.49 days and 66.82±2.17 per cent, respectively. The larvae passed through four instars. The average larval period was 11.78±1.02 days while pre-pupal and pupal period were, 1.32±0.47 and 6.56±0.50 days, respectively. The average pre-oviposition, oviposition and post-oviposition periods were, 8.68±0.653, 53.30±1.53 and 18.58±0.81 days, respectively. The average fecundity of the female was 1019.08±18.37 eggs during entire life span. The average longevity of male and female were, 85.48±2.16 and 80.56±1.47 days, respectively. Total life cycle lasted for 109.54±2.47 days (male) and 104.62±1.65 days (female). Z. bicolorata consumed 117.56±0.32 mg per individual when reared on P. hysterophorus whereas first and second instar larvae failed to feed on H. annus and could not survive. During entire life period, third, fourth instar larvae and adults consumed 14.18±0.28 mg per individual when reared on sunflower.