GYPSY-MOTH (LEPIDOPTERA, LYMANTRIIDAE) CONSUMPTION AND UTILIZATION OFNORTHERN RED OAK AND WHITE OAK FOLIAGE EXPOSED TO SIMULATED ACID-RAINAND OZONE

Two-year-old seedlings of white oak, Quercus alba L., and red oak, Q. rubra L., were exposed to ozone (O3) fumigations in four continuously stirred tank reactor chambers in the greenhouse for 8 h/d, 3 d/wk for 6 wk. Fumigation treatments were charcoal-filtered air (CFA) and CFA 0.15 ppm O3. Two simulated rain treatments, pH 4.2 and pH 3.0, of alm ost-equal-to 1.25 cm were applied once each week in rain-simulation ch ambers. Gypsy moth, Lymantria dispar (L.), third instars were allowed to feed on leaf disks from treated seedlings for 24 h. Leaf area consu med, food assimilated, weight gain, and relative growth rate (RGR) wer e examined. Overall, larvae fed white oak foliage consumed more foliag e and gained more weight than those fed red oak foliage. Response to t he fumigation and rain treatments was different for each oak species. On white oak foliage, larvae consumed significantly less foliage treat ed with CFA + pH 3.0 rain, but the lowest RGR occurred with the 0.15 p pm O3 + pH 4.2 rain treatment. The most food assimilated, greatest wei ght gain, and highest RGR occurred with the CFA + pH 4.2 rain control. Red oak foliage consumed was equivalent for all treatments, but folia ge exposed to CFA + pH 3.0 rain resulted in more food assimilated, gre ater weight gain, and higher RGR for that species.