Abstract :
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.
Keyword :
Choice test, Feeding behaviour, Non-choice test, Parthenium hysterophous.