Latitudinal variation in the life cycle of allodapine bees (Hymenoptera; Apidae)

The life cycles of Exoneura robusta and Exoneura angophorae are examined in four populations along the eastern seaboard of Australia, where climate ranged from temperate in the south to subtropical in the north over a latitudinal range of approximately 10°. These species were univoltine throughout the range examined and most colonies produced a single brood. Timing and duration of brood development in E. robusta varied between sites, with brood development being more rapid in northern populations; there was only weak evidence of any effect of latitude in E. angophorae. All populations of E. angophorae exhibited a small proportion of doubly brooded colonies, but doubly brooded colonies were found only in northernmost populations of E. robusta. Two-brooded colonies can give rise to opportunities for sib rearing, which can alter the indirect fitness benefits for alloparental care. Our results indicate that there is an effect of climate on sociality in E. robusta but no, or very little, such effect in E. angophorae.