Caste determination and differential diapause within the first brood of Halictus rubicundus in New York (Hymenoptera: Halictidae)

Social competition but not subfertility leads to a division of labour in the facultatively social sweat bee Megalopta genalis (Hymenoptera: Halictidae)

“…Thus, M. genalis foragers are capable of reproduction, but apparently are precluded from doing so by the presence of another, presumably dominant, female. This conclusion is consistent with most previous studies of sweat bees (Michener 1990;Mueller et al 1994), although foragers in some species do not retain reproductive ability (Michener 1990;Cronin & Hirata 2003), and replacement queens of temperate species are not always capable of entering diapause and subsequently establishing new nests (Yanega 1989). Some replacements may have already had enlarged ovaries at the beginning of our study, but the rarity of nests containing more than one female with developed ovaries among the nonremoval collections and among an independent sample of nests from the same population in 2003 (Smith et al 2007(Smith et al , 2008 suggests that most replacements began the study with small ovaries, and enlarged them following release from social competition.…”

Phenological, but not social, variation associated with climate differences in a eusocial sweat bee, Halictus ligatus, nesting in southern Ontario

“…Nest-based studies (e.g. Yanega 1989Yanega , 1990) provide a "gold standard" for revealing many crucial aspects of social behaviour in insects, because they allow us to infer colony social organisation and the consequences of interactions among nestmates. But when nests are difficult to find in large enough numbers to justify excavating and destroying them, sociobiological studies based on pan trapped specimens generate inferences about colony social organization and female reproductive behaviour that are a viable alternative.…”

“…First brood females with fewer fat stores than second brood females may be less likely to survive hibernation (Richards and Packer 1994), but their overwintering survival might be higher in places like St. Catharines with milder winters. Production of gynes in the first brood is well documented in the facultatively eusocial sweat bee, Halictus rubicundus (Yanega 1989), but in obligately eusocial bees production of large gynes before small workers within a single nest appears to be rare. This phenomenon has not previously been reported for H. ligatus, but has been observed in another obligately eusocial species, Lasioglossum malachurum (Wyman and Richards 2003).…”

“…For H. ligatus, the large numbers of queens followed by small numbers of workers suggest high rates of queen mortality and nest failure. For H. confusus, the large peak in female abundance at the time of worker provisioning of Brood 2, followed by a low abundance of gynes later in the summer, suggests the possibility of differential diapause by Brood 1 females, which instead of helping to raise Brood 2, begin hibernation in mid-summer, preparatory to founding nests the following spring (Yanega 1988(Yanega , 1989.…”

“…In sweat bees, eusociality is characterized by the behavioural totipotency of all adult females, such that any newly eclosed female is potentially capable of taking on either the queen or worker role (Yanega 1989(Yanega , 1990. The flexibility inherent in the behaviour of individual females is also observed at the level of entire colonies or populations, as there is considerable evidence for both intraand inter-population variation in colony social organisation, especially in response to local climatic conditions (Yanega 1993, Miyanaga et al 1999, Hirata et al 2005, Kocher and Paxton 2014.…”