EFFECT OF OVERSTORY DENSITY OF IPS PINI (COLEOPTERA, SCOLYTIDAE) PERFORMANCE IN PONDEROSA PINE SLASH

We evaluated the interactive effects of light intensity and aspect of small ponderosa pine, Pinus ponderosa Douglas ex Lawson, logs on the p erformance of pine engraver, Ips pini (Say). Low, moderate, and high l ight intensity (21,000, 47,000, and 67,000 lux, respectively), and top and bottom aspects of logs were crossed in a factorial experiment rep licated in 4 blocks of previously thinned pole-size ponderosa Dine. Lo g exposed at high natural light intensity were attacked less than logs exposed at low to moderate sunlight. Insects attacking logs exposed t o high light intensity exploited the subcortical environment scantily, which led to a low net brood production. Moisture content of phloem w as positively correlated with brood production. However, the highest m oisture content promoted interspecific competition from other wood bor ers, which resulted in low net brood production when moisture content of the phloem was high.