Developing a monitoring tool to understand the seasonal dynamics and management techniques to estimate a sampling plan for Xylosandrus compactus (Eichhoff) in Hawaiʻi

Ph.D. University of Hawaii at Manoa 2010.Includes bibliographical references.The potential damage caused by the invasion of exotic ambrosia beetles to Hawaiʻi is one of the biggest concerns for the coffee, forestry and ornamental plant industries. Most of these invasive beetles are from temperate areas and find a suitable environment for reproduction and survival in Hawaii, which is favored by climatic conditions, presence of alternate hosts and the lack of natural enemies. The black twig borer, Xylosandrus compactus (Eichhoff), is an important coffee pest and native forests in Hawaiʻi. This ambrosia beetle is highly polyphagous, reported from >200 hosts, including native plants such as the valuable timber species Acacia koa. This dissertation addressed the response of X. compactus to semiochemicals which were used to determine the beetle flight seasonality, phenology of the black twig borer in coffee plantations, and development of a sequential sampling plan for management decision making. It was demonstrated that Japanese beetle traps baited with ethanol can serve as monitoring tool for the black twig borer, and ethyl alcohol baits yielded higher capture rates than eugenol and α-pinene. It was also demonstrated that the repellents verbenone and limonene, significantly reduced trap catches of black twig borer. Ethanol baited Japanese beetle tras were used to assess the seasonal fluctuation of black twig borer throughout the year. Data obtained from trapping demonstrated the peak beetle flight periods, which were used as an predictor of damage levels for accurate timing of control measures. Elevation and season were significantly related with the number of beetles captured and level of infestation. Taylor's Power Law analysis showed an aggregated infestation of X. compactus in coffee fields. The density of infested branches per sampled unit can be estimated using the sampling plan and compared with the action threshold level to make a management decision. Enumerative sampling allows estimation of the black twig borer abundance with specified precision, providing researchers with a valid tool for the study of this pest in coffee. Three species of scolytines were detected attacking coffee berries in Hawaiʻi, Xylosandrus compactus, Hypothenemus obscurus and H. hampei. The biology, behavior and management of these three species are discussed