SEASONAL DISTRIBUTION OF ADULT ECLOSION, OVIPOSITION, AND PARASITISM AND PREDATION OF EGGS OF THE SPRUCE BUD MOTH, ZEIRAPHERA CANADENSIS (LEPIDOPTERA: TORTRICIDAE)

Abstract

AbstractSpruce bud moth adults eclosed in mid-July and completed oviposition within a period of 2 weeks at 8- and 11-year-old white spruce plantations and at an old-field site in northern New Brunswick. Parasitism of bud moth eggs by Trichogramma sp. started less than 14 days after the beginning of adult bud moth eclosion and increased until the middle of August. The temporal patterns of egg parasitism and predation of viable bud moth eggs were similar in 1988 when most mortality occurred during the 2 weeks following the end of oviposition. At two sites studied in 1989, most parasitism occurred during the 4–5 weeks, and predation during the 1–3 weeks following the end of oviposition. Examination of temporal patterns of parasitoid eclosion and of the incidence of parasitism suggests that second-generation parasitoids attacked bud moth eggs at two of three sites. Depending on site and collection date, predators either showed a strong preference for unparasitized eggs or ate similar proportions of unparasitized and parasitized eggs. The incidence of egg parasitism and predation was not influenced by egg density in 1988. In 1989, a weak negative relationship between the number of eggs per cluster and the incidence of egg parasitism was not significant. However, a significant proportion of the variation in percentage egg parasitism was attributable to the interaction between egg density per shoot and collection date.