Biocontrol host specificity testing of a chrysomelid flea beetle for the management of several noxious melastome weeds in Hawaii

Syphraea uberabensis (Coleoptera: Chrysomelidae) is a South American flea beetle whose adults and larvae feed externally on Tibouchina foliage and soft stems, causing enough damage to kill small plants. Under quarantine evaluation as a potential biocontrol agent for Tibouchina herbacea (Melastomataceae), S. uberabensis has been tested on a variety of native and non-native species within the order Myrtales to identify its expected host range in Hawaii. Multi-choice behavioral tests with adult beetles and no-choice tests with adults and larvae indicated a host range restricted to several species within the tribe Melastomeae, all of which are invasive weeds in Hawaii. Preferences were found for feeding and egg laying on two Tibouchina spp., Pterolepis glomerata, and Melastoma septemnervium, but S. uberabensis appeared unlikely to impact the other serious weeds including Tibouchina urvilleana, Miconia calvescens and Clidemia hirta. We consider the potential for using this biocontrol agent in management of a variety of weedy melastomes.