Lek size and female visitation in two species of tephritid fruit flies

The notion that females prefer to visit and mate with grouped over solitary males is an oft-advanced hypothesis for the evolution of lek behaviour. A corollary of this hypothesis is that per capita mating success of males inc reases with increasing lek size. Few field studies have tested this predict ion via experimental manipulation of lek size. Here, I describe field studi es that monitored female visits to artificially created leks of varying siz e in two species of tephritid fruit flies, the Mediterranean fruit fly, Cer atitis capitata, and the Oriental fruit fly, Bactrocera dorsalis. No suppor t for the female preference hypothesis was detected for B. dorsalis. Howeve r, in C. capitata, mean ratios of female sightings:signalling males were si gnificantly greater for leks containing 18 or 36 males than leks that conta ined only six males. The observation that C. capitata males in natural popu lations typically form small leks suggests that a female-male conflict exis ts regarding optimal lek size.