SURVEY OF ENTOMOPATHOGENIC NEMATODES IN VARIOUS LANDSCAPE SYSTEMS ON OAHU, HAWAII, AND THEIR PATHOGENICITY AGAINST COCONUT RHINOCEROS BEETLE (COLEOPTERA: SCARABAEIDAE)

Abstract

The use of locally available biological control agents (e.g., entomopathogenic nematodes, EPNs) can be an important tool in integrated pest management (IPM) programs of newly established invasive pests, such as coconut rhinoceros beetle (CRB), Oryctes rhinoceros (L.). With this aim, we surveyed EPNs from 12 landscape sites that included four public/recreational areas, six botanical gardens, and two forest reserves on the island of Oahu, HI. Overall, 35 (83.3%) of the total samples were found positive for EPNs and out of those samples, 20 (57.1%) samples yielded virulent strains. EPNs recovered from the surveyed sites were primarily composed of Heterorhabditis spp. Some Heterorhabditis spp. virulent strains were tested for pathogenicity against first instar CRB larvae. Although our study did not show significant effects of Heterorhabditis spp. strains against CRB larvae, some strains inflicted mortality of first instar larvae after 2 days as well as a week after exposure. Our findings indicated that the locally available strains of Heterorhabditis spp. could potentially be a useful biological control agent, in an IPM program, to control first instar CRB larvae. However, further research is needed to test virulent commercial strains of Heterorhabditid and Steinernematid against CRB larvae. The results of such studies will uncover if certain EPN strains could be incorporated as a part of CRB IPM program.