EFFECTS OF PHOTOPERIOD AND TEMPERATURE ON CALLING BEHAVIOUR OF THE GYPSY MOTH, LYMANTRIA DISPAR L. (LEPIDOPTERA: LYMANTRIIDAE)

Abstract

AbstractFemale gypsy moth, Lymantria dispar (L.), exhibited a distinct calling rhythm at 17 °C, with peak calling ca. 4.0 h before the beginning of scotophase and minimal calling at or near the onset of the photophase (4.0 h). The rhythm persisted under continuous darkness (DD) and is thus circadian. The duration of calling in DD was shorter than that under a 16 h L: 8 h D photoperiodic regime. In contrast, under continuous light (LL) females called continuously and no overt rhythm was observed. Individuals kept under LL from the beginning of the pupal stage exhibited a distinct calling rhythm following a transfer to DD. The influence of temperature on the calling rhythm of L. dispar differed from most other species of moths studied to date. At lower temperature the onset of calling occurred later than at higher temperatures. The duration of the calling period increased from 11.1 h at 9 °C to continuous calling at 35 °C. The responses of females to temperature changes made at different times during the calling period suggest that the timing of calling in L. dispar does not depend on absolute temperature level.