THE DIAPAUSE AND RELATED PHENOMENA IN <i>GILPINIA POLYTOMA</i> (HARTIG): I. FACTORS INFLUENCING THE INCEPTION OF DIAPAUSE

Abstract

This first in a series of five papers includes a review of the literature on diapause and an outline of the life cycle of the European spruce sawfly in Canada, especially the developmental stages within the cocoon. In studies of factors influencing the inception of diapause, evidence has been secured from offspring of stock from one-generation and two-generation areas that there are genetic differences within the species with respect to the capacity for development without diapause. Environmental factors are capable of bringing on diapause, and such factors are obviously operative during the development of the last seasonal generation of "emergent" field populations. However, analysis of weather conditions and incidence of diapause in such field populations failed to indicate correlation between the degree of diapause and any one environmental factor.