Efficacy of Entomopathogenic Nematodes and Sprayable Polymer Gel Against Crucifer Flea Beetle (Coleoptera: Chrysomelidae) on Canola

Abstract

The crucifer flea beetle, Phyllotreta cruciferae (Goeze), is a key pest of canola ( Brassica napus L.) in the northern Great Plains of North America. The efficacies of entomopathogenic nematodes ( Steinernema spp. and Heterorhabditis spp.), a sprayable polymer gel, and a combination of both were assessed on canola for flea beetle management. Plots were treated soon after colonization by adult flea beetles, when canola was in the cotyledon to one-leaf stage. Ten plants along a 3.6-m section of row were selected and rated at pre-treatment and 7 and 14 d post treatment using the damage-rating scheme advanced by the European Plant Protection Organization, where 1 = 0%, 2 = 2%, 3 = 5%, 4 = 10%, and 5 = 25% leaf area injury. Under moderate flea beetle feeding pressure (1–3.3% leaf area damaged), seeds treated with Gaucho 600 (Bayer CropScience LP Raleigh, NC) (imidacloprid) produced the highest yield (843.2 kg/ha). Meanwhile, Barricade (Barricade International, Inc. Hobe Sound, FL) (polymer gel; 1%) + Scanmask (BioLogic Company Inc, Willow Hill, PA) ( Steinernema feltiae ) resulted in the highest yields: 1020.8 kg/ha under high (2.0–5.3% leaf area damaged), and 670.2 kg/ha at extremely high (4.3–8.6 % leaf area damaged) feeding pressure. Our results suggest that Barricade (1%) + Scanmask ( S. feltiae ) can serve as an alternative to the conventional chemical seed treatment. Moreover, Scanmask ( S. feltiae ) can be used to complement the effects of seed treatment after its protection has run out.