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 landmark territories for from less than 1 day to several weeks. Variation in territory tenure could arise if territories differ in their value and cost to defend (the tradeoff hypothesis). If superior sites attract more male competitors, raising the cost of territorial defense of these locations, we would expect (1) tenure times to be shorter at top-ranked sites and (2) tenure 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 were shorter at top-ranked sites, the difference was only statistically significant in one of three years. IIE the year of highest male density, a significantly higher proportion of all territorial males failed to hold the tap-ranked sites for more than a single day; however, mean tenure duration at all occupied sites did not decline in this year: Thus, the tradeoff hypothesis received only partial support. An alternative hypothesis is that variation in male resource holding power; as reflected in male size or wing condition, contributes to differences in territorial tenure. However, although larger males tr)ere more likely to become territorial residents at the top-ranked sites, the duration of tenure at these locations was not positively correlated with body size. IPI addition, although wing condition declined throughout 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 territories longer than males whose wings were in poorer condition when they assumed control of a site.