Host specificity attributes of Zygogramma bicolorata Pallister in Chitrakoot Region, India

The Mexican beetle, Zygogramma bicolorata is an effective bio-control insect of Parthenium hysterophorus, which was introduced in 1983 from Mexico to Bangalore. The adult and grub stages of Zygogramma act as bio-control agents for invasive and a very dangerous weed, P. hysterophorus (Gajar ghas). Various indigenous and economically important plants of different seasons were selected for choice and non-choice tests; food and oviposition preferences of the beetles were analysed. Host specificity tests in non-choice cases revealed that Z. bicolorata showed host specificity according to feeding and oviposition only towards P. hysterophorus. Feeding behaviour was seen only on Parthenium plants in choice tests. So it was found beneficial to release Z. bicolorata in field conditions for defoliation of carrot grass.