Colony composition and behavioral characteristics of the myrmicine ant, Aphaenogaster rugulosa, an endemic species to Yonagunijima Island, the westernmost point of Japan (Hymenoptera: Formicidae)

Colony composition and behavioral characteristics of the myrmicine ant, Aphaenogaster rugulosa, a species endemic to Yonagunijima Island, were investigated. Colonies nested in rotten woods fallen on the forest floor. All queenright colonies (N = 42) were monogynous with one dealate queen. The average colony size in worker number was 140.5 +/- SD 94.9. Under laboratory conditions, workers and larvae fed on both fresh and dried insect preys. The workers used a kind of tool to transport diluted sugar water to the nest chamber. They dropped pine needles and trashes into the diluted sugar water and then transported the food-soaked materials back into the nest chamber, where nest members then sucked on the materials inside the nest chamber. Trophic eggs were laid by the workers, the majority of which were given to the larvae. The queens also fed on trophic eggs as well as insect preys. The workers under an orphan condition laid reproductive eggs that grew up to be males.