title: Does climate affect host-plant quality? Annual variation in the quality of balsam fir as food for spruce budworm.
abstract: The hypothesis that annual climatic variation can affect the nutritive value of host-plant tissue for a herbivore was tested. Larvae of a single generation of western spruce budworm, Choristoneura occidentalis Free., were fed foliages that had been collected on five consecutive springs from a stand of balsam fir Abies balsamea (L.) Mill. Budworm of both sexes were about 20 percent heavier at pupation when fed folages that had been produced in early rather than later spring seasons. This could result in an estimated 25 percent difference in the reproductive rate of females. It is concluded that annual variations in spring climate can affect the nutritive value of forage.
authors.affiliation: Department of Zoology, Division of Life Sciences, Scarborough Campus, University of Toronto, 1265 Military Trail, M1C 1A4, West Hill, Ontario, Canada.
authors.forename: Ian M
authors.initials: IM
authors.lastname: Campbell
keywords: Annual variation; Balsam fir foliage; Nutritive quality; Spruce budworm