Behavioral ecology of the Mediterranean fruit fly : leks, courtship, nuptial gifts, and average offspring

Abstract

Observations of the mating behavior of wild Mediterranean fruit flies, Ceratitis capitata (Wiedemann) in a semi-isolated orchard in Kula, Maui, Hawaii, revealed that matings occur on only a small proportion of available trees. Most matings occur during midday and in almost all cases 110 other males are present in the same tree as the mating pair. Intruders win more than two-thirds of all male-male interactions and females terminate most failed courtship attempts. Male size and territory location do not correlate with mating success and a small percentage of the males mate more than once. Mating frequency in the laboratory is non-random. Variation in male activity level accounts for some of the differential mating success. Male copulatory success is positively correlated with the number of courtships performed, attempted copulations (mountings) and females courted. Male-male aggression, on the other hand, has a negligible effect on male mating success. Female choice also appears to influence male mating frequency. Less than 10% of courtships result in mating, and in most cases females terminate courtship by simply moving away from the male. Females that do mate generally select males having higher copulatory scores than previously rejected males. The non-random mating of males does not appear to be a result of female preferences for heritable differences among males in the ability to obtain copulations. Father/son correlation and sibling analysis both show no additive genetic variance for male copulatory success. However, female preferences may act to increase fecundity. Females which mate with virgin males enjoy increased longevity and fecundity. Furthermore, there is a non-linear relationship between a male's copulatory success and female fecundity. Females mating males that obtain few (<2) or many (>6) matings enjoy increased fecundity. The basis for these relationships between male mating success and female fecundity is not known but may be based on sex-peptides passed to the female during copulation. Such direct benefits may help explain the lek mating system and the evolution of female choice in this species.