MATING-BEHAVIOR AND SEXUAL SELECTION IN THE AFRICAN BALL-ROLLING SCARAB KHEPHER-PLATYNOTUS (BATES) (COLEOPTERA, SCARABAEIDAE)

Mating behaviour of the ball-rolling dung beetle Kheper platynotus (Ba tes), adults of which are active in rainy seasons, was studied in sout heastern Kenya. Male mating behaviour changed with the progression of the rainy season. In the early season when females made food balls, ma les attempted forced copulation with wandering and food-ball-making fe males on dung mounds. As the season progressed, females made brood bal ls, and males attempted to pair off with such females, as well as atte mpting forced copulation with wandering and food-ball-making females. A male who paired off with a brood-ball-making female cooperated with the female to make the ball. The male usually copulate after burying t he ball (pre-copulatory mate guarding), but sometimes copulatory durin g ball-making In the latter case the male usually showed post-copulato ry mate guarding until ball burial, but sometimes left soon after copu lation. In the late season, when available females decreased because o f maternal care in the underground nests, males started to make food b alls to secure food resources for survival until the next rainy season . Male mate guarding involving ball-making, -rolling and -burying seem ed to function to raise paternity confidence, but such assistance seem ed to be less beneficial to females. Fights frequently occurred betwee n guarding and intruding males on brood balls. Both residency and rela tive body sizes of fighters were important asymmetries influencing con test outcome. This seemed to result in not active but passive mate cho ice by brood-ball-making females.