Wiliwili & Erythrina Gall Wasp Monitoring Project

Innoculative releases of a biological control agent (Eurytoma erythrinae) were initiated by the Hawai‘i Department of Agriculture (HDOA) in November 2008, to suppress populations of the Erythrina gall wasp, a destructive pest on native wiliwili trees (Erythrina sandwicensis). Releases were completed on all of the main Hawaiian Islands, with the exception of Ni‘ihau and Kaho‘olawe. Pre-release biological monitoring data were collected from a total of 16 monitoring sites on Kaua‘i, O‘ahu, Maui and Hawai‘i Island. DLNR-DOFAW is currently working with HDOA, UH Manoa and US Forest Service researchers to continue monitoring the long-term effects this predator is having on the pest populations and ultimately on wiliwili recovery. Results to date are exceedingly positive, indicating a significant reduction in pest populations, and the recovery of wiliwili trees statewide.

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Healthy wiliwili tree at Ulupalakua Ranch

Healthy wiliwili tree at Ulupalakua Ranch

Dead wiliwili trees at Makua Keaau Forest Reserve

Dead wiliwili trees at Makua Keaau Forest Reserve

Wiliwili branch with healthy leaves

Wiliwili branch with healthy leaves

Dead wiliwili branch with visible gall wasp damage

Dead wiliwili branch with visible gall wasp damage

Healthy but dormant wiliwili at Lahaina Luna

Healthy but dormant wiliwili at Lahaina Luna