BIOSYSTEMATICS OF THE GENUS EUXOA (LEPIDOPTERA: NOCTUIDAE): XIV. EFFECT OF TEMPERATURE ON FEMALE CALLING BEHAVIOR AND TEMPORAL PARTITIONING IN THREE SIBLING SPECIES OF THE DECLARATA GROUP

Abstract

AbstractThe calling behavior of females of three interfertile sibling species of Euxoa was studied in the laboratory at 20°, 15°, 10°, and 5 °C. At 20 °C the calling posture of E. campestris and E. rockburnei differs from that of E. declarata. However, with decreasing temperatures the calling posture of both campestris and rockburnei becomes indistinguishable from that of declarata. The pattern and duration of calling bouts was similar in all three species and at all four temperatures. Calling occurred progressively earlier in scotophase as temperature decreased but temporal separation between the calling periods of the three species is maintained at all temperatures above the threshold for mating activity. This confirms that temporal separation of mating persists over the range of temperature normally encountered in nature and strengthens the evidence that species-specific rhythms of mating activity are largely responsible for maintaining reproductive isolation between sympatric populations of these species.