OBSERVATIONS ON DISTRIBUTION, SEASONAL LIFE HISTORY, AND ABUNDANCE OF FLEA BEETLES (COLEOPTERA: CHRYSOMELIDAE) THAT INFEST RAPE CROPS IN MANITOBA

Abstract

Phyllotreta cruciferae (Goeze) was usually the most abundant flea beetle on crops of Argentine rape, Brassica napus L., in Manitoba, followed in order by Phyllotreta striolata (F.) and Psylliodes punctulata Melsh. These three species and small numbers of Phyllotreta bipustulata (F.) were present on volunteer rape in the spring. A few specimens of a fifth rape-eating species, Phyllotreta robusta Lee, were trapped in April after hibernating. The three main species were recorded in all 16 localities in which samples of flea beetles on rape crops and/or volunteer rape were collected. Details of seasonal life history of each species are presented, as well as data on the abundance of the three main species throughout the year on rape crops, in overwintering habitats and on volunteer rape in spring. The relative abundance of P. cruciferae, P. striolata, and Ps. punctulata in different rape-growing areas of Manitoba is discussed.