Degree-day accumulation controlling allopatric and sympatric variations in the sociality of sweat bees, Lasioglossum (Evylaeus) baleicum (Hymenoptera: Halictidae)

摘要: Halictine bees exhibit a wide range of social behaviour that varies both inter- and intraspecifically. Although previous studies suggested the intraspecific variation might be attributed to temperature differences, there was no direct evidence detect relationships between socialities. Lasioglossum (Evylaeus) baleicum exhibited solitary in cooler locality (Kawakita) because shorter breeding season; warmer (Nishioka Park), however, this bee species eusociality at sunny site shady site, whereas molecular phylogeny confirms all these colonies are evidently conspecific. Therefore, we examined effect degree-day accumulation on sympatric L. by rearing calculate threshold temperature. Whereas they showed high mortality, estimated 10.33°C expected 340 degree days. When use value estimate eclosion date, dates were always consistent with observed dates. In any sites where solitary, not enough for second end bee-active season. Nishioka Park, sex ratio first brood female biased, daughters smaller than mothers; Kawakita, bias, as large their mothers indicating foundresses seem produce gyne-sized females Kawakita but worker-sized though do become workers site.