Kukuk et al (1998) describe the nesting and foraging biology of Lasioglossum hemichalceum. This species is communal, meaning that multiple females live in the same nest and reproduce. Nests consist of tunnels dug into the soil, and occur in aggregations. The species occurs in eucalypt forests of southeastern Australia. Individuals co-habiting nests are not related. Females who have passed the previous winter in hibernation emerge in spring (November) to rear the first generation of offspring, consisting of males and females that are smaller than the overwintered foundresses. These summer-emerged males and females mate, and the females initiate their own nests, forming colonies with other unrelated females. The produce a second generation of small males (similar to those of the first offspring brood) and large, macrocephalic, males, and females. The small males disperse to mate with other females, while the macrocephalic males remain in their natal nest and mate with resident females. Females mate and overwinter to initiate nests the following spring. On average adult females reared 3.16 total offspring.
Despite being unrelated, females in summer nests are cooperative and share food via trophallaxis (mouth-to-mouth food transfer). Moreover, they cannot apparently recognize nestmates: females are indiscriminately cooperative towards all conspecifics. Some females in the nest do not forage. Foraging behavior is risky: on average, a forager survives only 8 days of foraging. All females had active ovaries. Kukuk et al. (1998) showed that without adult females present, offspring were attacked and consumed by ants. The authors hypothesize a “revolving door” model of nest guarding: non-foraging females remain at the nest and protect the offspring of foragers, who are likely to die soon. When the non-foragers later forage, the daughters of the early-foraging females are now in the nest to guard the eggs of the current foragers, and so on.
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