Factors influencing dispersal in neonate gypsy moths (Lepidoptera: Lymantriidae)

We studied the effects of date of hatch, maternal population quality, larval density, air temperature, and host foliage on the dispersal of neonate gypsy maths, Lymantria dispar (L.), under field conditions. Larval dispersal significantly increased with date by nearly fourfold, but neither maternal population quality nor crowding had a significant effect on dispersal activity. Neither variation in air temperature or length of egg chill were related to the increase in dispersal with date; this trend was best explained by the combined effects of foliar changes during leaf expansion and declines in host quality because of induced plant defenses. Our results indicate that environmental factors in the current generation, such as leaf expansion after budburst, have a much larger influence than maternal population quality on the dispersal of neonate gypsy moths under natural conditions.