Greenhouse studies were conducted in 2003 and 2004 to quantify and compare plant growth and yield of canola in response to simulated and crucifer flea beetle, Phyllotreta cruciferae (Goeze), feeding injury. Seedlings of 2 canola varieties, 357 RR a hybrid and Raider RR an open pollinated, were subjected to simulated and actual crucifer flea beetle feeding injury. Canola growth responses were determined for growth rate, seed yield and percent oil of seed at 10, 30, 50 and 70% injury levels. In both years, differences in canola growth rate responses were significant between the injury types and ranged from 2.6–14.9% across injury levels. Differences in growth responses for yield (i.e., seed yield and percent oil content) were significant between simulated and insect injury and ranged from 3.1–33.5% in 2003, and 1.3–67.9% in 2004 across injury levels. Both canola varieties generally showed a greater response in growth rate and yield parameters in response to simulated than crucifer flea beetle feeding injury. Simulated feeding injury tested in this study did not adequately mimic actual P. cruciferae feeding injury. Therefore, until an appropriate technique is found, mechanical injury cannot be relied on to substitute for P. cruciferae feeding injury.
3Entomology Department, North Dakota State University, Fargo, ND 58105.
4Agribusiness and Applied Economics Department, North Dakota State University, Fargo, ND 58105.