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EFFECTS OF PRE-STORAGE TREATMENT ON SURVIVAL OF DIAPAUSING LARVAE OF THE SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA (LEPIDOPTERA: TORTRICIDAE)1

Published online by Cambridge University Press:  31 May 2012

Arlene McMorran
Affiliation:
Insect Pathology Research Institute, Canadian Forestry Service, Sault Ste. Marie, Ontario

Abstract

At a constant temperature of 1 °C, survival of diapausing second-instar larvae of C. fumiferana (Clem.) for any given period is, to a large extent, determined by pre-storage treatment. At a pre-storage temperature of 20 °C larval survival was 80% or higher following storage periods ranging from 169 to 290 days. Survival of larvae pre-stored at 24 °C was never as high as at 20 °C, and the survival began to decrease after 225 days storage. At 28 °C this decrease had occurred before 169 days of storage. Larvae held at high pre-storage temperatures had almost normal survival when the pre-storage period was shorter. Mean time for larvae to emerge from diapause was increased by longer diapause periods and by high pre-storage temperatures. There was a corresponding decrease in larval vigour.

Résumé

A la température constante de 1 °C, la survie des larves de C. fumiferana (Clem.) en diapause au deuxième stade de leur développement est, pour toute période donnée, déterminée dans une large mesure par leur traitement de pré-emmagasinement A la température de 20 °C avant l’emmagasinement, la survie des larves fut de 80% ou plus après des périodes d’emmagasinement de 169 à 290 jours. La survie des larves pré-emmagasinées à 24 °C ne fut jamais aussi élevée qu’à 20 °C : leur survie commença à diminuer après un emmagasinement de 225 jours. A 28 °C, cet évènement se produisit avant 169 jours d’emmagasinement. Les larves tenues à de hautes températures de pré-emmagasinement avaient une survie presque normale lorsque la période de pré-emmagasinement était plus courte. Le temps moyen d’émergence de leur diapause fut augmenté par des périodes de diapause plus longues et par des températures élevées de pré-emmagasinement. Il y eut une diminution correspondante de la vigueur des larves.

Type
Articles
Copyright
Copyright © Entomological Society of Canada 1973

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References

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