Sucessful Control of the Erythrina Gall Wasp in Hawaii

 

The invasion of the Erythrina Gall Wasp (EGW), Quadrastichus erythrinae (Kim) in 2004 threatened the existence of E. sandwicensis in Hawaii. A promising biological control agent was collected in Tanzania and underwent rigorous risk assessment at the Hawaii Department of Agriculture insect containment facility. In November 2008, Eurytoma erythrinae (Gates & Delvare) was approved to be released into the environment to control EGW.  Pre- and post-release evaluations were initiated to evaluate the impacts of the biological control agent on the gall wasp and the Erythrina trees.  Regular sampling and gall dissections showed that the wasp became established within 6 months of its release. Results from post-release monitoring indicate that E. erythrinae is successfully controlling gall wasp populations in foliage at most sites, whereas infestation levels in inflorescences remain still high at some sites. Surviving wiliwili trees are recovering from gall wasp damage. Post-release monitoring continues in order to determine the impact that E. erythrinae will have on the species’ long-term viability.