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EFFICACY OF OIL-BASED FORMULATIONS OF BACILLUS THURINGIENSIS BERLINER VAR. KURSTAKI AGAINST THE HEMLOCK LOOPER, LAMBDINA FISCELLARIA FISCELLARIA (GUEN.) (LEPIDOPTERA: GEOMETRIDAE)

Published online by Cambridge University Press:  31 May 2012

R.J. West
Affiliation:
Newfoundland Forestry Centre, Forestry Canada, PO Box 6028, St. John's, Newfoundland, Canada A1C 5X8
A.G. Raske
Affiliation:
Newfoundland Forestry Centre, Forestry Canada, PO Box 6028, St. John's, Newfoundland, Canada A1C 5X8
A. Sundaram
Affiliation:
Newfoundland Forestry Centre, Forestry Canada, PO Box 6028, St. John's, Newfoundland, Canada A1C 5X8

Abstract

Oil-based formulations of Bacillus thuringiensis Berliner var. kurstaki, Dipel 132, Dipel 176, and Dipel 264, were aerially applied at rates of 1.18–2.36 L/ha over five 30-ha plots in a balsam fir, Abies balsamea (L.) Mill., forest in efficacy tests against the eastern hemlock looper, Lambdina fiscellaria fiscellaria (Guen.), in Newfoundland. Double applications of 30 Billion International Units (BIU) per hectare of each formulation and single applications of 40 BIU per hectare of Dipel 176 and Dipel 264 were tested. Larval population reductions of more than 95% and no defoliation of old or new foliage were observed in the plots receiving double applications and in the plot treated with a single application of Dipel 264. Larval numbers were reduced by 85% and defoliation was 4% in the plot treated once with Dipel 176.

These treatments were applied against low to moderate larval populations, and their success was attributed to excellent spray coverage and early application when 50% or more of the larvae were still in their first instar.

Résumé

Des essais d’arrosages aériens de formulations à l’huile de Bacillus thuringiensis Berliner var. kurstaki, les Dipel 132, 176 et 264, à des débits variant de 1,18–2,36 L/ha ont été effectués sur cinq placettes de 30 ha dans une forêt de sapins baumiers, Abies balsamea (L.) Mill., à Terre-Neuve, pour contrôler l’efficacité de ces formulations contre l’arpenteuse de la pruche, Lambdina fiscellaria fiscellaria (Guen.). On a étudié des applications doubles à la dose de 30 milliards d’unités internationales (MUI) par hectare pour toutes les préparations et des applications simples à la dose de 40 MUI par hectare pour le Dipel 176 et le Dipel 264. Dans les parcelles ayant reçu des applications doubles et la parcelle traitée par une seule application de Dipel 264, on a obtenu des réductions des populations larvaires dépassant 95% et aucune destruction du feuillage, vieux ou nouveau. Dans la parcelle traitée en une seule fois au Dipel 176, la réduction des larves a été de 85%, et la defoliation, de 4%.

Les populations larvaires variaient de faibles à modérées dans les parcelles traitées. Le succès obtenu est attribué à un excellent recouvrement des arrosages et à une application hâtive au moment où 50% des larves ou plus étaient encore au premier stade.

Type
Articles
Copyright
Copyright © Entomological Society of Canada 1989

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