Chronological vs. Physiological Age as Determinants of Mating Decisions: Studies on Female Choice Over Lifespan in An Acoustic Moth

Life history theory predicts that females may adjust the selectivity expressed in mate choice as they age. Particularly in cases where time is limiting, females are expected to reduce selectivity and thereby avoid losing a terminal mating opportunity. Some evidence for this reduction has been found in vertebrates and long‐lived insects, and several recent findings show that it may also exist in insects with very short adult longevities. Theory also predicts that behavioural adjustments should respond to remaining longevity (physiological age) rather than chronological age, but very little information relevant to this issue exists. We studied age‐related changes in mating behaviour in an acoustic moth species (Achroia grisella; Lepidoptera: Pyralidae) in which females choose males based on the intensity, rhythm and other temporal features of the male song, with the objective of determining whether observed adjustments reflect chronological or physiological age. In accordance with theory, we found that females became less selective in their evaluation of male song rhythm as they aged and that this adjustment was predicted by physiological rather than chronological age. The reduction in selectivity may be due to decreased movement and searching, factors that can prevent a female from perceiving all of the male songs being broadcast locally in a complex environment where the transmission of some songs is blocked in some locations. We did not observe these age‐related effects in a simpler, open environment.