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EGG WEIGHT AS A FACTOR IN THE OVERWINTERING SURVIVAL OF SPRUCE BUDWORM (LEPIDOPTERA: TORTRICIDAE) LARVAE

Published online by Cambridge University Press:  31 May 2012

G.T. Harvey
Affiliation:
Great Lakes Forest Research Centre, Canadian Forestry Service, Sault Ste. Marie, Ontario, Canada P6A 5M7

Abstract

Relationships between mean egg weight and overwintering survival in the laboratory were explored in selected large- and small-egg lines and also in first laboratory generations from 5 widely separated locations. Overwintering stress was provided by prolonged storage or above average storage temperature. Under stress large eggs were shown to have greater survival than small eggs in both stocks of insects. The results explain why spruce budworm from higher latitudes (longer winters) have heavier (larger) eggs. Other effects of prolonged storage and storage selection on subsequent size and development rates in both the treatment and the F1 generations are reported.

Résumé

Les corrélations entre la masse moyenne des oeufs et la survie à l'hibernation en laboratoire ont été examinées chez des souches à gros et à petits oeufs et aussi chez les premières générations élevées en laboratoire, mais originaires de 5 localités très éloignées les unes des autres. Les contraintes de l'hibernation ont consisté en un entreposage prolongé ou à une température supérieure à la moyenne. Dans ces conditions, la survie des gros oeufs des deux stocks d'insectes s'est révélée supérieure à celle des petits. Ces résultats expliquent pourquoi la tordeuse des bourgeons de l'épinette des latitudes élevées (aux hivers longs) pond de gros oeufs. D'autres effets de l'entreposage prolongé et de la sélection qu'elle opère sur la grosseur et le rythme de croissance des générations cobayes et F1 sont signalés.

Type
Articles
Copyright
Copyright © Entomological Society of Canada 1985

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