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CONE AND SEED INSECTS OF TAMARACK, LARIX LARICINA (DU ROI) K. KOCH, AND ATTEMPTS TO CONTROL DAMAGE USING CHEMICAL INSECTICIDES1

Published online by Cambridge University Press:  31 May 2012

P.A. Amirault  and
N. Rae Brown
P.A. Amirault
Affiliation:
Department of Forest Resources, Univerity of New Brunswick, Fredericton, New Brunswick, Canada E3B 6C2
N. Rae Brown
Affiliation:
Department of Forest Resources, Univerity of New Brunswick, Fredericton, New Brunswick, Canada E3B 6C2
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Abstract

An investigation of the insects that damage cones (megasporangiate strobili) and seeds of tamarack [Larix laricina (Du Roi) K. Koch] in New Brunswick was undertaken. During two growing seasons (1982 and 1983) cones were removed from natural and planted stands of tamarack on a weekly basis. These cones were dissected, the nature and amount of insect damage recorded, and insect habits documented. Efforts were made to rear to adults any destructive insects encountered in order to identify them and to isolate parasites. Insects destroyed from 24.6 to 88.0% of the seed produced in the stands under study. Larvae of the spruce budworm [Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae)] and the cone maggot [Lasiomma viarium (Huckett) (Diptera: Anthomyiidae)] were responsible for most of the damage. Among insects that caused lesser amounts of damage were a cone midge [Resseliella sp. (Diptera: Cecidomyiidae)], a seed chalcid [Megastigmus sp. (Hymenoptera: Torymidae)], and various lepidopterous larvae. Applications of the insecticides carbofuran and dimethoate reduced the amount of insect damage. Carbofuran applied at the rate of 13.5 g active ingredient per centimetre of diameter at breast height provided the best protection. Trees treated in this manner had 37.0% of their seeds destroyed by insects as opposed to 74.2% on control trees.

Résumé

On a étudie les insectes qui attaquent les cônes (strobiles mégasporangiés) et les graines du mélèze [Larix laricinia (Du Roi) K. Koch] au Nouveau-Brunswick. Au cours de deux saisons (1982 et 1983) on a recueilli hebdomadairement des cônes dans des boisés naturels ou plantés de mélèze. On a disséqué ces cônes et on a recueilli des informations sur la nature et l’ampleur des dommages dûs aux insectes, et sur la biologie de ces insectes. On a tenté d’élever jusqu’au stade adulte tous les insectes trouvés afin de les identifier et d’en inventorier les parasites. Les insectes on détruit entre 24,6 et 88,0% des graines produites dans les boisés étudiés. Les larves de la tordeuse des bourgeons de l’épinette [Choristoneura fumiferana (Clemans) (Lepidoptera : Tortricidae)] et les asticots de Lasiomma viarum (Huckett) (Diptera : Anthomyiidae) étaient responsables de la plupart des dommages. Parmi les insectes qui causaient des dommages plus mineurs, se trouvaient un moucheron [Resseliella sp. (Diptera : Cecidomyiidae)], un chalcide [Megastigmus sp. (Hymenoptera : Torymidae)], et les larves de divers lépidoptères. Des applications des insecticides carbofuran et diméthoate ont réduit les dommages. Le carbofuran à la dose de 13,5 g d’ingrédient actif par centimètre de diamètre à hauteur de poitrine a fourni la meilleure protection. La destruction des graines pour les arbres ainsi traités était de 37,0% comparativement à 74,2% pour des arbres témoins.

Type
Articles
Information
The Canadian Entomologist , Volume 118 , Issue 6 , June 1986 , pp. 589 - 596
Copyright
Copyright © Entomological Society of Canada 1986

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