Biological Studies on Zygogramma bicolorata Palltstei (Coleoptera : Chrysomelidae), a Potential Biocontrol Agent of Parthenium hysterophorus L. (Asteraceae)

Biological studies were carried out in Bangalore on the leaf feeding chrysomelid beetle, Zygogramma bicolorata Pallister, introduced for biological control trials against the neotropical weed Parthenium hysterophorus L. (Asteraceae). The insect completed its development in 27-29 days at 25.5 ± 1°C. sex ratio was in favour of females, with the males constituting only about 30% of the population. However, males lived longer (l22-271 days) than females (109-198 days). Although females were capable of laying up to 3368 (mean 2590.8) eggs each, only 30-52 % hatched.