Ethological Study of African Carpenter Bees of the Genus Xylocopa (Hymenoptera, Anthophoridae)

Over 200 bees of 4 African Xylocopa species were observed for 3 months on the island of Rubondo (L. Victoria, Tanzania). Some 40 burrows were investigated, 100 bees marked. Building techniques are minutely reported; burrow construction simplifies defence and allows re-use by succeeding generations. Food plants, collecting, provisioning and all aspects of ontogenesis are treated, insight given into pupal leg mobility and the much-debated emergence order after eclosion: the first-hatched bee, in the rearmost cell, prepares the way for siblings. Copulation and the copulatory hold are studied using tethered and illustrated. A few colonization experiments are described and a spectrogram of begging sounds given. Meeting of the generations, feeding of the young and nest-defence by young siblings throw light on the evolution of primitively eusocial communities. The known literature is reviewed in each chapter

Different ovarian responses to potential mates underlie species-specific breeding strategies in common marmoset and Goeldi's monkey

Callitrichids are cooperative breeders, characterized by obligate twinning, extensive paternal care, and monopolization of reproduction by the dominant female. This is the case in the common marmoset, and in common marmoset groups of more than one adult female, subordinate females are typically acyclic consistent with infertility. However, one callitrichid, Goeldi’s monkey, gives birth to singletonsand exhibits low paternal care. Given these reproductive traits of Goeldi’s monkey, we hypothesized that there would not be suppression of ovarian activity. To test this hypothesis, we applied non-invasive endocrine methods in a stepwise experiment with laboratory groups of both species. In each species, six pairs of sisters were studied alone, in visual contact with an unrelated male and in a polygynous trio with the male, and urine samples were collected for determination of oestrogen titres reflecting ovarian activity. Common marmoset sister pairs exhibited a marked difference in social status: during the study 5 of 6 dominant females conceived but only 1 of 6 subordinate females; the remaining 5 subordinates were acyclic at the end of the study, and instances of ovulation typically resulted in aggression. Goeldi’s monkey sister pairs showed no status differences: in all pairs, however, both sisters exhibited a temporary cessation of ovarian cyclicity on trio formation, followed by ovulation and conception. We conclude that these marked differences in ovarian responses reflect the differences in inter-female competition for paternal caregiving resources. In common marmosets with high inter-female competition, suppression of ovulation functions to reduce aggression received by subordinate females; in Goeldi’s monkey with low competition, temporary cessation of ovulation could facilitate female choice