Nesting biology and life cycle of Nomia (Acunomia) chalybeata Smith on Iriomote Island, southernmost Archipelago of Japan, with notes on the simultaneous occurrence of diapausing and non-diapausing prepupae within the same nests (Hymenoptera: Halictidae)

Nesting biology of the nomiine bee, Nomia (Acunomia) chalybeata Smith, was studied in Iriomote Island, Japan (N24°15–25 ) in 2003 and 2004. Its nesting period extended for 6 months from around the end of April to October. The nest aggregation was found in clay soil under shady conditions. Twenty nests/m^2 were present at the highest density spot. Brood numbers in solitary nests were 5–20 (mean ± SD: 11.8 ± 4.7, n= 14), and in communal nests 12–101 (43.0± 41.0, n= 3). Each brood cluster in communal nests contained 0–32 brood cells (10.1± 8.0, n= 13), uggesting that each cohabitant provisioned independently own brood cells. At least 2 and partially 3 generations were estimated to occur in the year; however each nest produced simultaneously ondiapausing and diapausing prepupae. The percent rate of diapausing prepupae differed seasonally, and was 20.0–37.5% (30.3 ±7.5%, n= 3) in overwintered generation and 0–100% (50.0± 39.8%, n= 9) in first generation, suggesting that the rate of production of dormant prepupae increased