Study on biology and morphometric aspects of Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae) on parthenium in Varanasi region, India

The work on biology of Zygogramma bicolorata reared on Parthenium hysterophorus was done in laboratory at department of entomology and agricultural zoology. The study show that the Mexican beetle oviposit small, oblong, elongated, light yellow or orange eggs on leaf surface and lid of Petri plate under laboratory condition. The average egg, larval, pre-pupal, pupal and adult period was found out to be 4.53±1.04 days, 13.80±1.36 days, 1.65±0.58 days, 9.95±0.85 days, 34.20±8.05 days (male) and 42.68±7.33 days (female). Hatching percentage and adult emergence percentage was 78.72±0.50 %, 71.08±2.81 % respectively. The larvae molted four times and the larval periods are 4.49±0.93 days (1st instar), 2.82±0.78 days (2nd instar), 3.40±0.63 days (3rd instar), 4.60±0.74 days (4th instar) respectively. Entire life cycle escalates to 61.42±7.31 days for male and 69.33±8.26 days for female. The average fecundity, pre-oviposition, oviposition, post oviposition periods and sex ratio were 663.5 eggs, 8.59±0.72 days, 44.26±1.53 days, 18.35±0.81 days and 1:1.35 respectively. Total average developmental period lasted for 26.82 days.