BARK BEETLE (COLEOPTERA, SCOLYTIDAE) OUTBREAK IN PINE FORESTS OF THE SIERRA DE LAS MINAS BIOSPHERE RESERVE, GUATEMALA

From 1992 to 1995 an outbreak of pine-infesting bark beetles occurred in eastern Guatemala, primarily along the southern slopes of the Sierr a de las Minas Mountains, between 500 and 2100 m elevation, in the Dep artments of El Progreso and Zacapa. Based on examination of bark beetl e-killed pine (Pinus) trees at several sites, Dendroctonus frontalis w as the principal mortality agent and Pinus oocarpa was the most affect ed tree species. Egg galleries similar to those of D, frontalis were a lso found on dead Pinus maximinoi and Pinus tecunumanii trees. Infeste d pine stands were typically unmanaged, overstocked, and located on st eep slopes. In addition, most outbreak areas had experienced frequent ground fires and overgrazing. The ultimate stressing agent that appare ntly triggered this outbreak was a severe regional drought in 1992. Be sides D. frontalis, other scolytids collected along the lower trunk of P. oocarpa trees were Dendroctonus parallelocollis, Ips calligraphus, Ips grandicollis, Pityophthorus confusus, and Xyleborus intrusus. At lower elevations, Ips calligraphus was the only scolytid collected fro m the lower trunk of infested Pinus caribaea. trees.