The Canadian Entomologist (2005) 137, 584-597

V.G. Nealis (2005)
Diapause and voltinism in western and 2-year-cycle spruce budworms (Lepidoptera: Tortricidae) and their hybrid progeny
The Canadian Entomologist 137 (5), 584-597
Abstract: Breeding experiments and rearing under variable controlled conditions have revealed that western and 2-year-cycle spruce budworms (Choristoneura occidentalis Freeman and C. biennis Freeman, respectively) from British Columbia, Canada, and their hybrid progeny have the inherent capacity for a variable number of diapause events and hence voltinism. While all crosses have at least one diapause, variability in the relative frequency of a second diapause is determined by genetic traits modified by the photoperiod and, to a lesser extent, temperature experienced during the larval stages. Second diapause appears fixed in C. biennis but is facultative and most frequent at short photophases (12L:12D) in C. occidentalis. Hybrids and backcrosses had responses intermediate to the parental responses under all environmental conditions. The occurrence of a facultative third diapause in all crosses underlines the inherent capacity for flexibility in voltinism in these species. These results are discussed in the context of past, present, and future distributions of alternative life cycles in closely related species.
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Link to article at publishers website
Database assignments for author(s): Vincent G. Nealis

Research topic(s) for pests/diseases/weeds:
population dynamics/ epidemiology
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Choristoneura freemani		Canada (west)
	Choristoneura freemani		Canada (west)