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PATHOGENICITY OF ASCOSPHAERA LARVIS TO LARVAE OF THE ALFALFA LEAFCUTTING BEE, MEGACHILE ROTUNDATA

Published online by Cambridge University Press:  31 May 2012

Mark S. Goettel ,
Grant M. Duke  and
D. Wayne Goerzen
Mark S. Goettel
Affiliation:
Lethbridge Research Centre, Agriculture and Agri-Food Canada, P.O. Box 3000, Lethbridge, Alberta, Canada T1J 4B1
Grant M. Duke
Affiliation:
Lethbridge Research Centre, Agriculture and Agri-Food Canada, P.O. Box 3000, Lethbridge, Alberta, Canada T1J 4B1
D. Wayne Goerzen
Affiliation:
Saskatchewan Alfalfa Seed Producers Association, 107 Science Place, Saskatoon, Saskatchewan, Canada S7N 0X2
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Abstract

Laboratory assays and field surveys showed that Ascosphaera larvis (Bissett) is a pathogen of alfalfa leafcutting bee larvae, capable of causing high mortality in commercial populations. In one population, over 21% of bees were found to be infected by A. larvis. However, overall levels of the disease are low and it is unlikely that this pathogen poses an immediate threat to commercial leafcutting bee populations in Canada. The LD50 was determined to be 1.9 × 105 spores/bee. Elevated levels of CO2 are required for in vitro spore germination. The disease can easily be diagnosed within bee cells by X-ray radiography, thereby enabling disease levels to be monitored using conventional methods utilized by the industry to monitor leafcutting bee quality.

Résumé

Des études en laboratoire ont démontré qu’Ascosphaera larvis (Bissett) est un pathogène des larves de la découpeuse de la luzerne, capable d’occasionner une mortalité importante au sein des populations commerciales. Chez une population examinée, plus de 21% des abeilles étaient infectées par A. larvis. Cependant, la maladie s’est avérée généralement bénigne et le pathogène ne constitue donc pas une menace immédiate pour les populations commerciales de découpeuses au Canada. Le LD50 a été évalué à 1,9 × 105 spores/abeille. Des concentrations élevées de CO2 sont essentielles à la germination des spores in vitro. La maladie est facilement diagnostiquée dans les cellules des abeilles par radiographie aux rayons X, ce qui permet d’en évaluer la gravité au moyen des méthodes conventionnelles utilisées industriellement pour apprécier la qualité des abeilles.

[Traduit par la Rédaction]

Type
Articles
Information
The Canadian Entomologist , Volume 129 , Issue 6 , December 1997 , pp. 1059 - 1065
Copyright
Copyright © Entomological Society of Canada 1997

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