author(s)
Dr. Sanghmitra

abstract
Invasive alien weed Parthenium hysterophorus L. is considered as one of the major threat to environment. It has adverse effect on human beings, livestock, crop yield, and biodiversity. In the present study during the survey of biocontrol agent for the management of parthenium number of insects such as Aphis gossypii, Phenococcus sp., Elasmucha grisea, leaf miner and Zygogramma bicolorata were observed on parthenium. Infestation of Aphis gossypii and Phenococcus sp. on parthenium was heavy and leaf miner and Elasmucha grisea was mild and infrequent respectively. These biocontrol agents also have wide host range thus not considered as suitable biocontrol agent. Due to very heavy infestation of Zygogramma bicolorata on parthenium and monophagus feeding habit, it was selected for detailed study. Insects were introduced at rosette stage of plant. After thirty days of continuous feeding, it was evaluated that there is reduction in plant height, shoot length, stem diameter, root length and plant biomass i.e., 65.11%, 56.16%, 23.63%, 12.39%, 71.63% respectively. It was also recorded that such insect fed plant did not attain flowering stage at all.