Management of coconut rhinoceros beetle (Oryctes rhinoceros) in Hawai'i

Coconut rhinoceros beetle (CRB, Oryctes rhinoceros) is a large scarab beetle native to Southeast Asia and a serious pest of palm species, most notably coconut and oil palms. CRB adults damage palms, particularly younger ones, by boring into the center of the crown, where they injure the young, growing tissues and feed on the sap. In Hawaii, CRB was first confirmed on Oahu in December 2013. Since then, USDA, Hawaii Department of Agriculture, University of Hawaii at Manoa, and other entities, launched the CRB eradication program. For biological control, we collected over 60 entomopathogenic fungal strains and over 20 entomopathogenic nematode strains from various sites on Oahu. Based on our lab assays, although entomopathogenic nematodes were ineffective, several locally collected Metarhizium strains and one commercial Beauveria strain caused >60% mortality of CRB larvae. Based on our consequent field experiments, the commercial Beauveria strain caused almost 70% mortality of CRB larvae in field conditions. For chemical control, we focused on low-risk systemic insecticides. Based on our lab assays, acephate and imidacloprid were very effective, causing 40% paralysis of CRB adults within 4 hours, 50% mortality of CRB adults within one day, and 100% mortality of CRB adults within three days. Based on these lab assay results, we conducted two field experiments using 70 coconut palms for 2 years. Our field experiment results indicated that imidacloprid was the most effective treatment in field conditions. The CRB eradication program has treated 3000+ coconut palms on Oahu to date based on our research results.