SEASONAL OCCURRENCE OF THE POWDERPOST BEETLE, DINODERUS MINUTUS, IN THE PHILIPPINES

The incidence of Dinoderus minutusvia.s evaluated over 24 months at the Makiling Forest Reserve Experimental Site (MFRES) in Laguna and 18 months at Kawayan Farm Experimental Site (KFES) in Rizal province using shelter traps. Beetle abundance was studied in relation to starch and moisture contents of bamboo, temperature, relative humidity, site elevation, rainfall and wind speed. The data were used to develop prediction models for beetle occurrence on freshly cut bamboo. Populations peaked from February to early June and declined or disappeared in the rainy season (July-October). Bamboo starch and moisture contents, temperature and relative humidity influenced D. minutus occurrence at MFRES, whereas only starch content and temperature significantly affected populations at KFES. Starch content best explained the variation in D. minutus occurrence at both sites. However, the direct relationship between temperature and starch production could also allow temperature to be used to predict beetle populations. The other factors were poorly correlated with beetle occurrence at both sites. Monitoring with shelter traps has considerable potential for managing bamboo harvesting to limit powderpost beetle attack.