New pest alert: Ramie moth,Arcte coerula (Lepidoptera: Noctuidae), in Hawaiʻi

In November 2018, the state of Hawaiʻi discovered the ramie moth, Arcte coerula (Lepidoptera: Noctuidae), on Maui defoliating māmaki trees, Pipturus albidus (Urticaceae). It was the first record of the ramie moth in Hawaiʻi and the United States. As of November 2020, this new pest has spread to Hawaiʻi island. Native Hawaiian māmaki has cultural, ecological, and agricultural importance to Hawaiʻi as a medicinal plant in traditional lāʻau lapaʻau practices, an essential food source for endemic insects, and a newly emerging tea crop, respectively. Leaf feeding on māmaki by the invasive ramie moth caterpillar can devastate these trees. This project assessed the ramie moth’s threat to Hawaiʻi through studies looking at its biological impact on the state’s natural and agricultural systems. We determined the current geographic distribution of the ramie moth in Hawaiʻi, identified its impacts on māmaki and other potential host plants, and analyzed potential control efforts to manage the ramie moth’s population in Hawaiʻi. Outcomes from this project will provide the state with crucial information to contain the spread of this new pest in Hawaiʻi, thus potentially saving an important part of our native forests, preserving the state’s emerging māmaki tea industry, and reducing millions in long-term management costs.