Abstract: | Field and laboratory studies revealed that the mating system of a tephritid fly, Procecidochares sp., meets even the most stringent definition of lekking behavior. Mark-recapture and plant-preference experiments confirmed that newly emerged adult Procecidochares sp. left their larval host plant (Chrysothamnus nauseosus) and flew to Atriplex canescens. The flies used A. canescens solely as a mate encounter site. Sex ratios of emerging flies did not differ from unity, but sex ratios at the leks were extremely male-biased. An advantage for larger individuals in male-male aggressive encounters was quantified and observations suggested that females might be choosing mates based on outcomes of fights. Lekking behavior, previously reported among polyphagic tephritids, is considered exceptional for a monophagous species. Factors favoring a lek mating system in this species are discussed. |