Strategies for the Biological Control of Parthenium hysterophorus L. in Eastern Pakistan

The arrival of the invasive agricultural weed parthenium, Parthenium hysterophorus , in Pakistan was first noted in the Gujrat district of the Punjab Province in 1980. The plant has now spread further in the Punjab Province as well as into Khyber Pakhtunkhwa (KP), the Islamabad Capital Territory (ICT) and Azad Jammu and Kashmir. The heartlands of parthenium infestation are in the central and northern districts of Punjab, the ICT and KP, and the weed is moving into the southern parts of Punjab and north-eastern KP. Given parthenium’s highly invasive nature, it is likely that it has already spread into the southern parts of Punjab, especially as the area is home to extensive irrigated farming, and it is possible that the plant has even reached Sind and Baluchistan provinces in the south and south-west of Pakistan. To date, two biological control agents for parthenium have reached Pakistan without being introduced deliberately, most likely arriving from India or Nepal: Zygogramma bicolorata – the Mexican or parthenium leaf beetle – and Puccinia abrupta partheniicola , or winter rust. This case study assesses the effectiveness of these existing biological control agents in Pakistan, the potential of redistribution projects to increase their impact and whether artificially inducing Z. bicolorata to emerge from diapause early could further stem parthenium growth in spring. The second part of the case describes the importation of the stem-boring weevil Listronotus setosipennis into a quarantine facility for host range testing. The plan is to boost Pakistan’s biological control programme by releasing the weevil in areas where parthenium occurs. Finally, the case also recommends additional biological control agents and strategies for the future. The biological control of Parthenium hysterophorus L. in Pakistan: Status quo and future prospects'. Management of Biological Invasions (2021), Volume 12, Issue 3: pages 509-526. This is an open access article distributed under terms of the Creative Commons Attribution License (Attribution 4.0 International - CC BY 4.0). © CAB International 2023