Spread of parthenium weed and its biological control agent in the Punjab, Pakistan

Abstract

Parthenium weed is invasive in many regions worldwide. In Pakistan, parthenium weed was first reported from Gujarat district of Punjab Province in 1980s. After 20 years of slow spread, it has spread rapidly in the past 10 years into many districts of Punjab and Khyber Pukhtunkhwa and possibly to Sind Provinces. Parthenium weed is now a dominant weed in wastelands and is becoming a problematic weed in irrigated and rainfed cropping systems, pasture lands, forests and national parks. Studies conducted prior to 2000 indicated that parthenium weed was only infesting the northern districts of Punjab. However, a recent survey carried out in 2009 on distribution of parthenium weed and its biological control agent Zygogramma bicolorata, a leaf defoliating beetle, had revealed that this weed has rapidly spread while biological control agent is spreading in a zone behind that of weed. The weed has now moved from northern to southern districts of Punjab and is threatening many other districts such as Okara, Pakpattan, Sahiwal, Khanewal, Multan and Bahawalpur. The presence of parthenium weed in southern Punjab is a potential threat to cotton and dairy industries of Punjab.