Oviposition Behavior of the Female Coconut Rhinoceros Beetle, Oryctes rhinoceros (Coleoptera: Scarabaeidae)

Abstract

The coconut rhinoceros beetle (CRB), Oryctes rhinoceros (L.) (Coleoptera: Scarbaeidae), has become one of the most important coconut and oil palm pests to date. CRB recently emerged in December 2013 as a new invasive pest of coconut palms on O‘ahu, Hawai‘i. Since its detection, efforts have been expended performing delimiting and monitoring surveys, detecting and sanitizing breeding sites, and developing methods for eradication and control. To aid these efforts, information on the factors influencing female adult oviposition behavior and identifying these behaviors is needed. In this study, data and observations were collected from a series of substrate choice tests and depth observations to assess if both lab-­‐reared and wild-­‐caught CRB have a preference for oviposition site or egg-­‐laying pattern. Small or large particle sizes, as well as high (8dS/m) or low (2 dS/m) salinity substrates, were tested and oviposition depths were observed using an observational chamber. Female CRB were found to prefer small particle size substrate and lay their eggs in an aggregated dispersion pattern at various depths up to 119 cm. No preference for substrate salinity was found. Additionally, female CRB were found to differ significantly in their oviposition behavior between lab-­‐reared and wild-­‐ caught beetle types. These results can help to identify potential breeding sites and can also be implemented into management programs for future eradication and prevention efforts.