Development of a second generation for the carrot weevil (Listronotus oregonensis) in the province of Quebec, Canada.
Gagnon A-È & Bourgeois G. 2019. Development of a second generation for the carrot weevil (Listronotus oregonensis) in the province of Quebec, Canada. Entomological Society of America, St. Louis, Missouri, USA.
The carrot weevil, Listronotus oregonensis, is an important pest of carrots causing yield losses of up to 50%. In recent years, control of this pest has been found to be more complex in carrot producing areas of Quebec, Canada. This situation is mainly explained by an extension of the activity period of adults, complicating the pest control management strategy. The objective of this study was to evaluate the impact of temperature increases on the phenology of carrot weevil. In a field experiment, we observed the activity period of adults, egg laying duration and larval development in carrot plots exposed to two different climatic conditions. In order to increase air temperature in the field, a plot of carrots was set up under a tunnel to increase the temperature by 1°C compared to a control plot without any shelter. Weevil phenology was greatly affected by temperature increases and was expressed mainly by the extension of egg laying period. The proportion of mated and sexually mature females was higher at the end of the season under warmer climatic conditions compared to ambient temperatures. Inhibition of the reproductive diapause under warmer conditions can explain why females were still active in the field at the end of the season. In addition, the abundance of the four larval stages of carrot weevil during the growing season demonstrates the presence of two cohorts, and thus, confirming the presence of two generations in northern regions. These results concretely show that the recent increase in temperatures is changing the phenology of this pest and will lead to modifications in pest management strategies.