Dramatic Observations of Two Biological Control Agents of Clidemia hirta on Kauai

Koster’s curse, Clidemia hirta (L.) D. Don, is a non-native invasive shrub threatening Hawaiian wet forests and watersheds. Since 1953, it has been subjected to a suite of biological control agents yet remains an important understory weed. In 2009, The Nature Conservancy of Hawaii noticed major defoliation on C. hirta from Colletotrichum gloeosporioides f. sp. clidemiae Trujillo, a leaf fungus. Observations were also made of the recently released seed predator moth Mompha trithalama Meyrick, suggesting high infection rates and premature fruit drop. A survey conducted in 2010 found C. gloeosporioides and M. trithalama ubiquitous across windward Kauai. While the two biological control agents have little effect on plant mortality, there is evidence to suggest possible impacts to seed production and overall leaf cover.