PARASITISM OF OVERWINTERING PUPARIA OF THE CABBAGE MAGGOT, DELIA RADICUM (L.) (DIPTERA: ANTHOMYIIDAE), IN RELATION TO HOST DENSITY AND WEATHER FACTORS

Abstract Puparia of Delia radicum collected in late autumn at Winnipeg and Portage la Prairie (Manitoba), St-Jean-sur-Richelieu (Quebec), London (Ontario), and St. John’s (Newfoundland) were parasitized mainly by Aleochara bilineata (Gyllenhal) (Coleoptera: Staphylinidae) and Trybliographa rapae (We...

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Bibliographic Details
Published in:The Canadian Entomologist
Main Authors: Turnock, W.J., Boivin, G., Whistlecraft, J.W.
Format: Article in Journal/Newspaper
Language:English
Published: Cambridge University Press (CUP) 1995
Subjects:
Insect Science
Molecular Biology
Physiology
Ecology, Evolution, Behavior and Systematics
Structural Biology
Canada
Newfoundland
Online Access:http://dx.doi.org/10.4039/ent127535-4
https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0008347X0001717X
Description
Summary:Abstract Puparia of Delia radicum collected in late autumn at Winnipeg and Portage la Prairie (Manitoba), St-Jean-sur-Richelieu (Quebec), London (Ontario), and St. John’s (Newfoundland) were parasitized mainly by Aleochara bilineata (Gyllenhal) (Coleoptera: Staphylinidae) and Trybliographa rapae (Westwood) (Hymenoptera: Cynipidae). At Winnipeg, St-Jean, and St. John’s parasitism by A . bilineata was high (<94%) and by T . rapae was low (<3%). At London, both parasitoids attacked less than 14% of the host puparia. At Winnipeg, host population density was related to parasitism by A . bilineata and to the temperature and rainfall during June and July. Parasitism by A . bilineata may be related to cumulative degree-days over 5°C during June and July at Winnipeg and during June and September at London. In Canada, the parasitoid complex is not effectively stabilizing host population density. The introduction of additional parasitoid species should be considered.

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