Consumption of Carrot Weevil (Coleoptera: Curculionidae) by Five Species of Carabids (Coleoptera: Carabidae) Abundant in Carrot Fields in Southwestern Quebec

Abstract

Five species of carabids ( Pterostichus melanarius Illiger , Pterostichus lucublandus Say, Bembidion quadrimaculatum oppositum Say, Clivina fossor L., and Anisodactylus santaecrucis F.) were offered carrot weevil eggs, fourth instars, pupae, teneral or overwintered adults in single and multiple food choice tests. In single food tests, all species consumed three or more stages of carrot weevil. The smaller carabids ( B. quadrimaculatum oppositum and C. fossor ) were the best consumers of eggs; the largest carabid, P. melanarius , was the only species that consumed high numbers of teneral and overwintered adults. All species were good consumers of fourth instars and pupae. In multiple choice food tests, P. melanarius and C. fossor consumed the same stages as in the single food tests and showed no preference for any particular weevil stage. In contrast, A. santaecrucis and B. quadrimaculatum oppositum had a preference for pupae, whereas P. lucublandus selected fourth instars. These preferences were not shown in the single food tests indicating the importance of multiple choice food tests for assessment of polyphagous predators. In voracity tests, P. melanarius and P. lucublandus consumed three times more than A. santaecrucis or B. quadrimaculatum oppositum .