Plant-Insect Ecosystems
Student Competition 10-Minute Paper
Lesley Lubenow
East District Director
North Dakota State University Extension Service
Langdon, North Dakota
Janet J. Knodel
Professor & Extension Entomologist
North Dakota State University
Fargo, North Dakota
Patrick Beauzay
Research Specialist, ND State IPM Coordinator
North Dakota State University
Fargo, North Dakota
Veronica Calles Torrez
Post-Doctoral Research Scientist
North Dakota State University
Fargo, North Dakota
Travis Prochaska
North Dakota State University
Minot, North Dakota
Ryan Buetow
North Dakota State University Extension
Dickinson, North Dakota
Don C. Weber
USDA-ARS
Beltsville, Maryland
Ashot Khrimian
USDA-ARS
Beltsville, Maryland
North Dakota is the leading canola producing state in the United States. Neonicotinoid insecticide seed treatment have been used management of Phyllotreta flea beetles over the past 17 years by the majority of growers (95%). The overwintering generation of Phyllotreta striolata Fabricius and P. cruciferae Goeze were collected from northeast (Langdon) and P. cruciferae from the north central (Minot) and southwest (Dickinson) areas of North Dakota. Wild P. striolata were live trapped using an aggregation lure and wild P. cruciferae using a kairomone. Canola seed was treated with three insecticide treatments: thiamethoxam (400 g/100 kg seed, neonicotinoid), clothianidin (200.8 g/100 kg seed, neonicotinoid), and cyantraniliprole (1000 g/100 kg seed, diamide). In the greenhouse, 10 flea beetles were placed in a bioassay cup containing five canola plants at either 7 and 14 days after planting. Mortality and feeding injury ratings were assessed at three and seven days after initial infestation. At Langdon, P. striolata, had significantly lower mortality and higher injury ratings than P. cruciferae for thiamethoxam, clothianidin and cyantraniliprole seed treatments. For P. cruciferae at all locations, all insecticide seed treatments had greater mortality and lower injury ratings than the untreated check. Cyantraniliprole mortality tended to equate to thiamethoxam and clothianidin by Day 7. Due to the reliance and continuous use of neonicotinoid insecticide seed treatments, Phyllotreta flea beetles are developing increased tolerance to the neonicotinoid insecticide seed treatments tested, especially for P. striolata.