Prioritising biocontrol agents for management of Miconia crenata (Vahl) Michelang in Australia

Abstract

Miconia crenata, a perennial shrub native to the neotropics, is an aggressive invader of natural and cropping environments in Asia, the Pacific and tropical Queensland, Australia. The leaf- and shoot-feeding thrips, Liothrips urichi, has been utilised as a classical biological control agent for management of this weed in the Pacific for nearly a century. More recently, L. urichi was subjected to host-specificity testing for the first time since its original prioritisation in the 1920’s, as part of a risk assessment for its release into Australia. While M. crenata was confirmed to be L. urichi’s preferred host, adults were found to be capable of oviposition and full development on multiple non-target test species under both no-choice and multi-choice scenarios. A submission to release the agent into the Australian environment is still under consideration on the basis that there have been no reported incidences of off-target impacts in the field where the agent has been released. Additional laboratory testing has been proposed to ascertain the behavioural and physiological mechanisms underlying its host usage. Concurrently, host-specificity testing of the leaf-spot fungal pathogen, Colletotrichum clidemiae, has commenced. The pathogen has previously been released in Hawai’i, where it damages M. crenata plants growing in shaded, moist conditions. Testing is being conducted on behalf of Australia by the Centre for Agriculture and Biosciences International (CABI).