Evaluation of foliar and seed treatments for control of the cabbage seedpod weevil (Coleoptera: Curculionidae) in canola

Abstract

Caged assays and field tests were used to evaluate the effectiveness of organophosphorus, pyrethroid, neonicotinoid, and biologically derived insecticides for reducing populations of the cabbage seedpod weevil, Ceutorhynchus obstrictus (Marsham), a new pest of canola in Canada. Complete mortality of caged weevils occurred 48 h after treatment with disulfoton, deltamethrin, carbofuran, oxydemeton-methyl, and chlorpyrifos. Under field conditions, using plots or large strips in commercial fields from 1998 to 2001, only deltamethrin and cyhalothrin-lambda (both pyrethroids) consistently reduced weevil densities, even at high population levels. Chlorpyrifos also significantly reduced weevil numbers and damage in some years, but results were variable and efficacy was too low to manage weevils under outbreak densities. Other insecticides such as spinosad provided moderate weevil control and may have a role in weevil management depending on their effect on beneficial insects relative to more efficacious insecticides. Treatment of canola seed with imidacloprid, lindane, or acetamiprid did not reduce weevil damage. Further research is needed to establish economic thresholds for C. obstrictus in canola, to assess the effect of insecticides on nontarget natural enemies of canola insect pests, and to assess the potential for integration of chemical agents with biological and cultural control strategies. Résumé-Des bioessais en cages et des tests sur le terrain nous ont permis d'évaluer l'efficacitéd'insecticides organophosphorés, pyréthrinoïdes et néonicotinoïdes, ainsi que des insecticides d'origine biologique, pour la réduction des populations du charançon des siliques de colza, Ceutorhynchus obstrictus (Marsham), un nouveau ravageur du canola au Canada. Un traitement au disulfoton, à la deltaméthrine, au carbofuran, à l'oxydéméthon-méthyle ou au chlorpyrifos entraîne une mortalité totale des charançons en cages en 48 h. Dans des parcelles ou des bandes dans des champs commerciaux en conditions naturelles de 1998 à 2001, seules la deltaméthrine et la cyalothrine-lambda (toutes deux des pyréthrinoïdes) réduisent les densités de charançons de façon soutenue, même lorsque les populations sont abondantes. Certaines années, le chlorpyrifos réduit aussi significativement les nombres de charançons et les dommages aux récoltes, mais ses effets sont variables et son efficacité trop faible pour le contrôle des charançons aux densités de niveau épidémique. D'autres insecticides, tels que le spinosad, procurent un niveau de contrôle moyen et peuvent avoir un rôle dans la lutte contre les charançons, tout dépendant de leur impact 476

Biochemical markers for cabbage seedpod weevil (Ceutorhynchus obstrictus (Marsham)) resistance in canola (Brassica napus L.)

“…Finally, larval exit holes in pods can serve as entry points to fungal infection further damaging remaining seed in the pod . Severe yield reductions from C. obstrictus infestations have led producers to increase pesticide applications (Cárcamo et al 2005), consequently harming the environment and costing additional millions of dollars (Colautti et al 2006). Adults of C. obstrictus respond to various endogenous plant chemical concentrations and combinations as well as visual stimuli during feeding and reproduction, although the exact stimuli for such behavior are yet unknown (Smart and Blight 1997).…”

Structural Study at the Gas‐Liquid Interface of 1‐Alkyl‐3‐Methylimidazolium Alkylsulfates Using Surface Potential Measurements

“…In southern Alberta, flea beetle populations can be high even when plants are caged, because beetles can overwinter in crop stubble from the previous year. However, it is unlikely that the lindane seed treatment negatively affected C. obstrictus preimaginal development, because, in three site‐years of study in the same ecoregion, Cárcamo et al 15 found that larval emergence from pods of canola grown from seed treated with lindane was not significantly different from emergence in plants grown from untreated seed.…”

Plant Nutrients and the Spatiotemporal Distribution Dynamics of <I>Ceutorhynchus obstrictus</I> (Coleoptera: Curculionidae) and Its Parasitoids

“…Control of C. obstrictus in canola currently involves application of broad spectrum chemical insecticide to entire Þelds when populations exceed threshold densities , Cárcamo et al 2005. Precision spraying involves application of pesticides to areas of high pest density rather than to entire Þelds, and this approach has been recognized for its potential effectiveness for control of the cabbage seedpod weevil (Ferguson et al 2000).…”