Development of Birch Leaves and the Growth Energetics of Epirrita Autumnata (Geometridae)

摘要: Larvae of Epirrita autumnata hatch at the time budburst, and feed on immature foliage mountain birch, Betula pubescens ssp. tortuosa. The effects leaf maturation, temperature, larval instar growth performance were measured in two seasons. Leaf water, nitrogen, phosphorus content declined with while toughness specific mass increased. There was a sharp decline rate attributable to maturation; for example relative third—instar larvae dropped from 0.52 0.11 mg°mg—1°d—1 3 d. Consumption rate, digestive efficiency, nitrogen utilization efficiency mature leaves; assimilation as consequence. frass production remained very constant. consumption appeared be limited by postingestive handling indigestible tissue. Effects maturation greatest warm temperatures. Third—instar grew faster than later instars early season leaves, fifth (last) least sensitive seasonal effects; differences between make them well suited leaves that they normally encounter. phenological constraint imposed exacerbated adaptations maximize young foliage, seems an important selective force influencing duration timing growth.