Biosystematics of the genus Euxoa (Lepidoptera: Noctuidae). XI. Mating discrimination between three closely related species of the declarata group

Abstract

The sibling species Euxoa declarata, Euxoa campestris, and Euxoa rockburnei will, in the laboratory, produce vigorous and fertile hybrid progeny from all interspecific combinations. Although interspecific matings occur readily under no-choice conditions there is a significant reduction, compared with intraspecific levels, in both the proportion of females mated and the occurrence of multiple mating. Tests for mating discrimination using the male-choice method show that ethological premating isolation between the three species is strong. In nature the ethological barriers in combination with other factors such as slight differences in seasonal flight period and habitat preference probably ensure complete reproductive isolation between the three species.