Bioclimatic approach to assessing factors influencing shifts in geographic distribution and relative abundance of two flea beetle species (Coleoptera: Chrysomelidae) in North America

Abstract

AbstractCrucifer flea beetle, Phyllotreta cruciferae (Goeze) and striped flea beetle, Phyllotreta striolata (Fabricius) (Coleoptera: Chrysomelidae) are the most chronic and economically important flea beetle pests of cruciferous (Brassicaceae) crops in western Canada. There have been reports that populations of P. striolata are increasing in numbers and expanding their geographic range. Climate is the fundamental factor regulating the distribution and abundance of most insect species. Bioclimate simulation models of the two flea beetle species were developed to assess climatic factors influencing shifts in their geographic distribution and density. The results fostered a better understanding of how the two species responded to selected climate variables. Growing seasons with above average precipitation were predicted to favour the geographic distribution of P. striolata more than P. cruciferae. Both P. cruciferae and P. striolata were sensitive to temperature changes in the range of −2 °C to +2 °C. The ecoclimatic index (suitability index) for P. cruciferae increased with increasing temperatures, whereas the index for P. striolata declined with increasing temperatures. This study highlights the regions of the Prairies and Boreal Plains Ecozones that are most sensitive to shifts of the two populations and which may require changes in insecticidal seed treatments for effective control.