Parthenium, Parthenium hysterophorus L. poses a serious environmental and socioeconomic threat in Pakistan. It was identified as a priority for control in Pakistan
and an integrated control programme has been launched against this invasive weed.
In 2009 the biological control agent, Zygogramma bicolorata Pallister, was documented
in Pakistan and thought to have naturally dispersed into the region. Despite the presence
of this biological control agent for the past decade in Pakistan, the population level
impact on parthenium weed has been limited by several factors, including climate,
diapause and limited dispersal. A redistribution programme was initiated to promote
this biological control agent in Pakistan. In addition to this, the parthenium winter
rust, Puccinia abrupta Diet. & Holw. var. partheniicola (Jackson) Parmelee, was
reported in Pakistan for the first time in 2019. Despite this rust being widespread
there appears to be limited impact, most likely linked to environmental conditions
and the timing of infection. Monitoring programmes for this rust have been initiated
for the winter of 2020. CABI, through its Action on Invasives programme, has
established a quarantine facility for the screening of complementary biological control
agents not yet in Pakistan against parthenium and other invasive weeds in the
country. With this quarantine facility the importation of the stem boring weevil,
Listronotus setosipennis (Hustache) was possible and host range testing is underway.
The biological control of parthenium in Pakistan is still at an early stage, and
considerable effort is required to fill the management toolbox for this invasive weed.