Fighting and mating behaviors of dimorphic males in the ant

Abstract

-Colony composition in CardiocondyIa wroughtoni and the fighting and mating behaviors of 2 types of males, alates and ergatoids, are described. This species is polygynous, with a mean of 7.0 queens per nest, and forms polycalic colonies. Within nests, ergatoid males fight with each other, leading to the death of all but one in single nests. On the other hand, alate males exhibit no aggressive behavior towards any of their colony members. Both types of males conduct intranidal mating with their sisters, though the alate males also conduct nuptial flights. Many alate females leave their maternal nest even if they have already been inseminated by intranidal mating.Ergatoid males, that is, wingless workerlike ones, are known among some ants of the genera Hypoponera, Formieoxenus and Cardioeondyla.

Behavior of ergatoid males in the ant,Cardiocondyla nuda

“…In such situations, adult males of C. nuda usually ignored each other. In contrast, Kinomura and Yamauchi (1987) and Stuart et al (1987) reported deadly fighting between adult rivals in C. wroughtonii, which lasted for hours. During these fights, but also when attacking callows, males of C. wroughtonii used their forelegs to beat the opponent and to spread secretions from the gaster tip over his cuticle.…”

“…Stuart et al (1987) suggested that different degrees of relatedness might underlie the observed variation in male-male compatibility. In C. wroughtonii, in addition to ergatoid males, winged males occur which are thought to disperse for mating in addition to intranidal mating (Kinomura and Yamauchi, 1987;Stuart et al, 1987). In contrast, in C. nuda, as well as in several other species (Kugler, 1983) winged males have never been found.…”

“…Fighting among males and female defense polygyny, on the other hand, "make sense" in evolutionary terms only if males are capable of inseminating numerous alate queens. According to Kinomura and Yamauchi (1987) ergatoid males of C. wroughtonii mated nine times in 12 hours, and winged males 113 times (! ), however, sperm transfer was not demonstrated and "mating" may have been mating attempts.…”

“…The readiness of C. nuda queens to mate a first time and the general rejection of males by older alate queens might indicate that multiple inseminations are rare. More detailed observations are needed to clarify this aspect, because multiple matings by alate queens were observed in C. wroughtonii (Kinomura and Yamauchi, 1987).…”

“…Ergatoid males of Cardiocondyla wroughtonii have long, sabershaped mandibles which they use to kill eclosing males and to attack adult rivals. Nests typically contain only one or a few ergatoid males, which inseminate all eclosing queens (Stuart et al, 1987;Kinomura and Yamauchi, 1987). Fighting, leading to severe injuries and death, was observed also among ergatoid males of Hypoponera punctatissima (Hamilton, 1979).…”