Beetle on the battle: Defoliation of Parthenium hysterophorus by Zygogramma bicolorata in Kathmandu valley, Nepal

Abstract

Zygogramma bicolorata, a Mexican beetle, is the most widely distributed biocontrol agent of the invasive weed Parthenium hysterophorus. The occurrence and distribution of this beetle in Nepal has been poorly documented. We monitored and mapped the occurrence of this beetle in Kathmandu valley for two years from August 2009 to September 2011. A small population of the beetle was first encountered in a wasteland at Sundarighat of Kirtipur Municipality in August 2010. By September 2011, the beetle has spread over half of the valley areas where P. hysterophorus was present, but damage to the weed was appreciable only at Sundarighat. The effectiveness of biocontrolling process is likely to be limited by shorter period of defoliating activity of the beetle, prolific seed production by Parthenium round the year, and environmental pollution.

doi: http://dx.doi.org/10.3126/botor.v8i0.5559

Botanica Orientalis – Journal of Plant Science (2011) 8: 100-104