Evaluating the current integrated pest management recommendations in Canada for carrot weevil (Coleoptera: Curculionidae) and carrot rust fly (Diptera: Psilidae)

Abstract

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.

Population genetic structure of the carrot weevil (Listronotus oregonensis) in North America

“…The genotype characterization of the pest populations at the local scale represents an opportunity to find markers of interest that are associated with specific biological functions or biochemical processes. For example, insecticide resistance threatens the success of pest control programs, with carrot weevils from commercial fields in Ontario having developed resistance to the foliar insecticide phosmet (Telfer et al, 2019 ). Considering that low dispersal capacity of adults constrains gene flow between populations, we might expect a rapid spread of insecticide resistance in carrot weevil populations at local scale following strong selection and limited input of new susceptible individuals.…”

“…The genotype characterization of the pest populations at the local scale represents an opportunity to find markers of interest that are associated with specific biological functions or biochemical processes. For example, insecticide resistance threatens the success of pest control programs, with carrot weevils from commercial fields in Ontario having developed resistance to the foliar insecticide phosmet (Telfer et al, 2019).…”

Evaluating the impact of cultivar selection on carrot weevil (Coleoptera: Curculionidae) damage and foliar insect pest assemblages in carrot

“…Currently, management of these insect pests relies heavily on synthetic insecticides and biopesticides (Geoffriau and Simon 2020). However, insecticide resistance threatens the utility of insecticides against carrot pests (Telfer et al 2018a, 2019).…”

“…Carrot weevil has been reported to cause yield losses of 40% or more in carrot and parsley, despite implementation of IPM strategies that include population monitoring, crop rotation, field sanitation, and repeated insecticide applications. Additionally, there are growing concerns about the development of carrot weevil resistance to pyrethroid active ingredients in Canada (Telfer et al 2018b, 2019). Although cultivar selection has not been deployed as a strategy against the carrot weevil, there is evidence in Quebec and Nova Scotia, Canada that the adults exhibit preferences for different crop hosts, based on their oviposition behavior.…”