Biology of Zygogramma bicolorata Pallister on Parthenium hysterophorus (Linnaeus).
The biology of Zygogramma bicolorata was studied on Parthenium hysterophorus in the laboratory from July 2005 to January 2006. The mean premating, mating and preoviposition periods were 3.37, 0.42 and 5.67 days, respectively. Oviposition, post-oviposition, incubation and larval periods were 27.73, 24.97, 3.54 and 10.58 days, respectively. The pupal period and total developmental period were recorded as 9.07 and 26.67 days, respectively. The longevity of male and female was 74.33 and 64.93 days, respectively, while the total male and female life cycle was recorded 100.84 and 91.35 days, respectively. The fecundity varied from 1346.4 to 1965.5. The hatchability of eggs varied between 70.00 and 82.50%. The emergence of adults from pupae varied from 78.33% in December to 91.67% in July and the sex-ratio was 1:3 during July-December.