Release, recovery and establishment of Mexican beetle, Zygogramma bicolorata Pallister (Chrysomelidae: Coleoptera) on Parthenium hysterophorus Linnaeus proliferating in and around Delhi

A total of 68 inoculative releases of Zygogramma bieoforata through niche release and satellite release were made in and around Delhi during 2001–03 and were found effective against P. hysterophorus. The beetles were seen in mating position besides scanty eggs mainly on lower sIdes of the leaves and terminal shoots. The adult and its larval stages prevailed in the field during extreme winter period (December 2004–January 2005) indicating their establishment with in three years of release. This constitutes the first report on recovery and establishment of Z. bicolorata from Delhi and around (Rohtak and Ghaziabad). Lush green Parthenium growth was observed on 21 sites during winter, which were identified as ideal release sites. As many as 100 eggs, 6–17 adults and 12–19 grubs were noted during April–May 2005 on a single shoot, which qualified to be termed as “Beetle Bowl”.