Biology and morphometric studies of mexican beetle, Zygogramma bicolorata Pallister on Parthenium

Studies on biology of Zygogramma bicolorata on Parthenium hysterophorus revealed that average egg, larval, pupal and adult period was 3.93 ± 0.80, 13.87 ± 1.36, 7.40 ± 1.18 and 32.40 ± 8.05 (males) to 44.53 ± 7.33 (females) days, respectively. Entire life-span of female and male completed in 59.13 ± 7.75 and 71.33 ± 8.78 days, respectively. In general, females found relatively larger in size than males. Fecundity, hatching percentage, adult emergence percentage and male to female sex ratio was 669.73 ± 141.34 eggs, 55.75 ± 12.2%, 76.67 ± 14.8% and 1: 1.26, respectively. Morphometric observations on different life stages of Z. bicolorata showed that the average length and breadth of eggs were 1.02 ± 0.16 and 0.49 ± 0.08 mm, respectively. Length of first, second, third and fourth instar larvae was 1.75 ± 0.11, 2.84 ± 0.12, 4.94 ± 0.13 and 6.25 ± 0.12 mm, respectively. Length and breadth of male beetles were 6.27 ± 0.10 and 3.41 ± 0.16 mm, respectively while it was 6.64 ± 0.08 and 3.71 ± 0.09 mm in case of female.