CORRELATION OF COUNTS OF GYPSY MOTHS (LEPIDOPTERA, LYMANTRIIDAE) IN PHEROMONE TRAPS WITH LANDSCAPE CHARACTERISTICS

The effect of landscape characteristics (elevation, slope, aspect, and vegetation) on counts of gypsy moths in pheromone traps was studied i n a >5 million ha area in Virginia and West Virginia from 1988 to 1994 . Habitat effects on population numbers depend on dominant ecological processes in the area: we define K-, r-, and c-effects as differences in carrying capacity, population growth rate, and colonization rate, r espectively, that are associated with different landscape characterist ics. To differentiate among these effects, we analyzed individually th e following three zones at the expanding front of the gypsy moth popul ation: infested (K-effects), transition (r-effects), and uninfested (c -effects), Among landscape characteristics, elevation was most highly correlated with moth counts, Moth counts increased with increasing ele vation in the infested and transition zones (K- and r-effects) which m ay be associated with good habitats at high elevation. However, the hi ghest average moth counts in the uninfested zone were found at low ele vation. Possibly this was a c-effect which resulted from a greater col onization rate in the low-elevation areas where human population densi ties are greater and the probability of inadvertent transfer of egg ma sses on human Vehicles is increased, The effect of vegetation on moth counts was much less pronounced than the effect of elevation, Moth cat ches were higher in deciduous and mixed forests than in coniferous for ests and nonforested areas. The effect of landscape characteristics on moth captures was stronger in the transition zone than in other zones .