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A STANDARDIZED BIOASSAY FOR LARVICIDAL ACTIVITY OF BACILLUS THURINGIENSIS IN SUNFLOWER MOTH HOMOEOSOMA ELECTELLUM (LEPIDOPTERA: PHYCITIDAE)

Published online by Cambridge University Press:  31 May 2012

R. G. Lidstone
Affiliation:
Bioinsecticide Laboratory, Department of Applied Microbiology and Food Science, University of Saskatchewan, Saskatoon S7N 0W0
D. W. Goerzen
Affiliation:
Bioinsecticide Laboratory, Department of Applied Microbiology and Food Science, University of Saskatchewan, Saskatoon S7N 0W0
G. G. Khachatourians
Affiliation:
Bioinsecticide Laboratory, Department of Applied Microbiology and Food Science, University of Saskatchewan, Saskatoon S7N 0W0

Abstract

A standard test for the larvicidal activity of Bacillus thuringiensis (B.t.) against the larvae of the sunflower moth Homoeosoma electellum (Hulst) has been developed. Bioassay parameters investigated include diet preparation, concentration of B.t., effect of formaldehyde, and method of pathogen incorporation in diet. The LC50 for seconded third-instar larvae is 1.24 μg of Dipel® WP ml−1 or 19.8 IU B.t. ml−1 pathogen-incorporated diet. Layering of a pathogen-suspension upon the surface of the diet was not a reliable bioassay technique for H. electellum. The addition of formaldehyde in the diet reduced the slope of the dose–mortality curve but did not change the LC50.

Résumé

Un test standard d'activité larvicide de Bacillus thuringiensis (B.t.) contre les larves de pyrale de tournesol, Homoeosoma electellum (Hulst) a été développé. Les paramètres suivants de bioassay on été exploré : préparation de l'aliment; concentration de B.t.; effet de la formaldehyde; le procédé pour incorporer le pathogène dans l'aliment. Le LC50 pour les larves du deuxième et troisième instar est 1.24 μg/ml Dipel® ou 19.8 IU/ml B.t. pathogène incorporé dans l'aliment. Pour la technique de bioassay, une couche de nés pension pathogène sur la surface de l'aliment ne s'est pas avère satisfaisant. Dans l'aliment, l'addition de la formaldehyde a réduit la pente de la courbe de dose-mortalité, mais n'a pas changé le LC50.

Type
Articles
Copyright
Copyright © Entomological Society of Canada 1985

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