Intraspecific variability in the tapping behavior of the deathwatch beetle,Xestobium rufovillosum (Coleoptera: Anobiidae)

Abstract

Taps were recorded from 46 male and 30 female deathwatch beetles, Xestobium rufovillosum.Beetles tap by striking the frons of the head on the substrate 4–11 times, at a frequency of about 11 Hz. There were no significant differences between the sexes in the number of strikes per tap, or in the frequency of the strikes, although there was significant variation between individuals of both sexes in both of these parameters. Males usually initiate a sequence of taps, to which females reply. Females responded more readily to male beetle taps containing high strike numbers. Use of an artificial tapper showed that females responded most to taps containing at least six strikes. Females did not discriminate between male beetle taps on the basis of strike frequency, although at abnormally high (20-Hz) or low (4-Hz) frequencies produced by the artificial tapper, females were less likely to respond. Male beetles located the source of taps from the artificial tapper and did this more readily with taps of a high strike number. It is not clear why some males produce taps with fewer than six strikes, as these are unlikely to elicit a female response, and so should be the subject of adverse sexual selection.