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The primary insect pests in Canadian carrot production are carrot rust fly (Psila rosae (Fabricius); Diptera: Psilidae) and carrot weevil (Listronotus oregonensis (LeConte); Coleoptera: Curculionidae). An integrated pest management programme for these pests exists in Québec and Ontario, where most Canadian carrot (Daucus carota subsp. sativus (Hoffmann) Schübler and Martens; Apiaceae) production occurs. As current carrot insect integrated pest management recommendations are decades old, laboratory and field trials were performed to evaluate the carrot insect integrated pest management recommendations. Carrot weevil populations were evaluated in the laboratory for resistance to the primary product used for control, phosmet. Ontario carrot weevils exhibited negligible mortality when exposed to phosmet compared with > 80% mortality in a susceptible strain. Using data from a carrot integrated pest management programme, weather data was correlated with monitoring and damage data of both pests from historical records. Increased carrot weevil captures were weakly related to increased damage. Carrot weevil damage was reduced by following integrated pest management recommendations in one of three trials. No strong relationship between weather and carrot rust fly captures was identified, suggesting the degree day model for carrot rust fly activity needs revision. In field trials, carrot rust fly damage was negligible despite integrated pest management recommendations for insecticide applications. Future research should include improving carrot weevil monitoring and control and increasing the carrot rust fly action threshold to optimise insecticide applications.

Carrot rust fly (CRF), Psila rosae (Fabricius, 1794) (Psilidae: Diptera) and carrot weevil (CW), Listronotus oregonensis (Le Conte, 1857) (Curculionidae: Coleoptera) are economic pests of carrot; larval tunneling on roots results in direct damage rendering the carrot unmarketable. The Holland Marsh in Ontario, Canada, is a major carrot production area. The ground-dwelling beetle (Coleoptera) fauna in commercial carrot fields in this region has not been described. In 2015 and 2016, eight commercial carrot fields were surveyed using pitfall traps to determine abundance and diversity of the ground-dwelling beetle complex. Research sites, which were used to evaluate the effectiveness of an existing integrated pest management (IPM) program, were also surveyed to determine the impacts of the IPM program on the natural enemy diversity, compared to insecticide-free sites. In total, 50 taxa and 4,127 individual ground-dwelling beetles were identified over the course of the 2 y. Known natural enemies of CRF and CW were identified and recovered in abundance. The abundance and diversity of ground-dwelling beetles among the commercial carrot fields varied greatly in 2015 and 2016 but was similar on research sites sprayed according to the IPM program compared to insecticide-free sites in both years. The importance of this research to promote conservation biological control through the naturalization of nonagricultural areas is discussed.

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