Queens remate despite traumatic mating in stingless bees

Abstract

Males can control female reproduction using genital plugs to impede access by rivals. In social bees, ants and wasps, plugging may involve traumatic mating, with females being harmed. In stingless bees, chances are that plugs may promote ovarian activation, and are thought to ensure single mating—a general tendency among the social Hymenoptera. However, understanding on relationships between mating plugs, traumatic mating, and mating systems in stingless bees remains limited. To address this, we (i) compared mated queens of seven Neotropical species to understand the patterns of copulatory marks in females; and (ii) compared pre- and post-mating genitalia of males and females in M. fasciculata to depict plug functional morphology. Data revealed an unprecedented consequence of mating in stingless bees: the characteristic marks left by mating plugs on female abdomens and the inferences that can be made from them. To our surprise, in one species M. fasciculata we found that queens retain the plug long after mating, and may carry it for the rest of their lives. All the other six species retained the plug for only a short period. Remated queens were only found in M. seminigra, whose multiple copulatory marks match previous findings of polyandry in this species. Our study shows that queens can remate, and suggests that male genital morphology may determine in part the time persistence of plugs. We conclude that traumatic mating plugs do not fully prevent remating in stingless bees and that mating systems are not uniform in this group. Nonetheless, exceptional cases of facultative polyandry in social insects—e.g. when mating plugs fail—may confirm a general tendency for single mating in close link with efficient mating plugs.

Gene Flow from Wild to Managed Colonies in the Stingless Bee Scaptotrigona Mexicana and an Update on its Mating Frequency

“…In principle, such proximity among related colonies might promote inbreeding, and studies have shown that the gynes of some stingless bee species such as Melipona mondury, M. beecheii, Lestrimellitta limao, Nannotrigona perilampoides, Paratrigona subnuda, S. postica, and S. depilis can mate up to six times (Paxton et al, 1999a;Paxton, 2000) but others, such as Trigona fulviventris, just once (Green & Oldroyd, 2002;Palmer et al, 2002;Vollet-Neto et al, 2018;Vollet-Neto et al, 2019). Veiga et al (2021) suggested that the quality of the plug formed by the male genitalia remaining in the mated queen is involved because such plugs that are difficult for the queen to remove and thereby increase the probability of single mating. There is also a trade off between single and multiple mating strategies.…”

“…In contrast, polyandry (multiple mating) decreases the frequency of diploid males, reduces parasitism, and increases genetic diversity (Baer & Schmid-Hempel, 1999;Tarpy & Page Jr, 2001;Borges et al, 2010;Jaffé, 2014). Thus, whether colonies have single or multiple patrilines depend upon the species, the efficacy of mating plugs and other factors still to be revealed (Peters et al, 1999;Veiga et al, 2021). In prior studies with S. mexicana, Kraus et al (2008) found that the majority of patrilines in managed colonies apparently originated from wild colonies and not from managed ones within the same meliponaries.…”

Untargeted Lipidomics Analysis Unravels the Different Metabolites in the Fat Body of Mated Bumblebee (Bombus terrestris) Queens

“…Previous studies on the reproduction of bumblebee queens have focused on ovarian status, hormone effects, nutritional metabolism, feed composition, intestinal bacteria species, and environmental factors [6][7][8][9][10][11]. Most insects reproduce sexually, and the physiology and behavior of female insects change post mating [12][13][14][15][16][17]. After honey bee and bumblebee queens mate with drones, the expressions of immune-and sperm storage-related genes in spermathecae are significantly up-regulated [18,19].…”