First release and establishment of the biological control agent Cecidochares connexa for the management of Chromolaena odorata (L.) R.M. King & H. Rob (chromolaena) in Australia

Abstract

Chromolaena odorata (L.) R.M. King & H. Rob (chromolaena or Siam weed) is a scrambling invasive shrub native to tropical America that significantly impacts terrestrial systems in Africa, SE Asia and, more recently, northern Australia. After its northern Queensland detection in 1994, C. odorata was part of a national cost-share eradication program until 2012 when eradication was deemed unfeasible. Anticipating the risk of C. odorata to the Australian environment, host testing commenced on the stemgalling fly Cecidochares connexa (Macquart), which was approved for release in 2018. This is Australia’s first biological control agent for Chromolaena odorata.