Dispersion and sequential sampling plan for Xylosandrus compactus (Coleoptera: Curculionidae) infesting Hawaii coffee...

The black twig borer, Xylosandrus compactus (Eichhoff) (Coleoptera: Curculionidae: Scolytinae), is a serious pest of coffee (Coffea arabica L.) in the Kona region of the island of Hawaii, the center of the largest area of coffee production within the state of Hawaii. This study indirectly characterizes the spatial distribution of X. compactus in coffee plantations through assessment of twig borer damage, and presents a sequential sampling plan for monitoring X. compactus population densities. Taylor's Power Law (TPL) and Iwao's mean crowding index showed that X. compactus infestations were highly aggregated within plantations, with b and ß values significantly larger than 1. The TPL linear regression of log variance against log mean (R2 = 0.92) provided a better fit to the data than the linear regression of mean crowding on the mean (R2 = 0.68). Subsequently, Taylor's power law parameters were used to develop the Green's sequential plan to estimate densities of X. compactus at the 90 and 75% precision levels.