Possible causes of variation in territory tenure in a Lekking pompilid wasp (Hemipepsis ustulata) (Hymenoptera)

Territorial males of the pompilid wasp Hemipepsis ustulata occupy their lan dmark territories for from less than 1 day to several weeks. Variation in t erritory tenure could arise if territories differ in their value and cost t o defend (the tradeoff hypothesis). If superior sites attract more male com petitors, raising the cost of territorial defense of these locations, we wo uld expect (1) tenure times to be shorter at top-ranked sites and (2) tenur e times to decline in years of high male density and competition. Although mean tenure times for males able to hold territories for at least 2 days we re shorter at top-ranked sites, the difference was only statistically signi ficant in one of three years. IIE the year of highest male density, a signi ficantly higher proportion of all territorial males failed to hold the tap- ranked sites for more than a single day; however, mean tenure duration at a ll occupied sites did not decline in this year: Thus, the tradeoff hypothes is received only partial support. An alternative hypothesis is that variati on in male resource holding power; as reflected in male size or wing condit ion, contributes to differences in territorial tenure. However, although la rger males tr)ere more likely to become territorial residents at the top-ra nked sites, the duration of tenure at these locations was not positively co rrelated with body size. IPI addition, although wing condition declined thr oughout the flight season in concert with a sharp decrease in the duration of tenure at the top-ranked sites, males with fresher wings did not hold te rritories longer than males whose wings were in poorer condition when they assumed control of a site.