THE RED TURNIP BEETLE, ENTOMOSCELIS AMERICANA (COLEOPTERA: CHRYSOMELIDAE): DISTRIBUTION, TEMPERATURE ADAPTATIONS, AND ZOOGEOGRAPHY

Abstract

AbstractMost of the range of the red turnip beetle, Entomoscelis americana Brown, lies within the Western Cordillera and Interior Plains physiographic regions of North America between latitudes 45°N and 68°N. Entomoscelis americana is associated mainly with three types of vegetation: forests, forest–grasslands, and grasslands. Temperature adaptations in the egg, larval, pupal, and adult stages that permit E. americana to occupy its present range are outlined. Host plant abundance may be the main factor preventing eastward extension of its range. Climate and host plant abundance together appear to limit E. americana to low altitude locations north of 60°N latitude. Eight of the temperature adaptations of the egg and adult stages together seem to limit southward extension of the range. Entomoscelis Chevr. appears to have a Holarctic distribution, with 11 species in the Palearctic region and one (E. americana) in the Nearctic region. The stock giving rise to E. americana may have migrated to North America during the Pleistocene when the Bering land bridge was in existence. Entomoscelis americana likely spent the Wisconsinan glacial period south of the ice in the Western Cordillera and (or) in central United States.