Vol.:(0123456789) 1 3 Journal of Comparative Physiology A https://doi.org/10.1007/s00359-019-01323-7 ORIGINAL PAPER Foraging strategies and physiological adaptations in large carpenter bees Hema Somanathan 1  · Preeti Saryan 1  · G. S. Balamurali 1 Received: 5 December 2018 / Revised: 19 February 2019 / Accepted: 21 February 2019 © Springer-Verlag GmbH Germany, part of Springer Nature 2019 Abstract Large carpenter bees are charismatic and ubiquitous fower visitors in the tropics and sub-tropics. Unlike honeybees and bumblebees that have been popular subjects of extensive studies on their neuroethology, behaviour and ecology, carpenter bees have received little attention. This review integrates what is known about their foraging behaviour as well as sensory, physiological and cognitive adaptations and is motivated by their versatility as fower visitors and pollinators. This is evi- dent from their extremely generalist foraging and adeptness at handling diverse fower types as legitimate pollinators and as illegitimate nectar robbers. They purportedly use traplining to forage between isolated patches and are long-distance fyers over several kilometres suggesting well-developed spatial learning, route memory and navigational capabilities. They have a broad range of temperature tolerance and thermoregulatory capabilities which are likely employed in their forays into cre- puscular and nocturnal time periods. Such temporal extensions into dim-light periods invoke a suite of visual adaptations in their apposition optics. Thus, we propose that carpenter bees are an excellent though understudied group for exploring the complex nature of plant-pollinator mutualisms from ecological and mechanistic perspectives. Keywords Apidae · Flight activity · Foraging · Nocturnality · Xylocopa Biology of large carpenter bees Large carpenter bees of the family Xylocopinae include some of the largest bees with a distribution across the trop- ics, sub-tropics and occasionally in temperate regions (Hurd and Moure 1960). Given the Oriental-Palaearctic origin of the genus, their current distribution is the result of inde- pendent dispersal events (Leys et al. 2002). Within the fam- ily Apidae, they are grouped into the cosmopolitan genus Xylocopa, which comprises at least three clades and ca. 470 species (Leys et al. 2002; Michener 2007). As their name suggests, almost all carpenter bees construct nests in dead or decaying wood, except those belonging to Proxylocopa, a soil-nesting subgenus (Gottlieb et al. 2005). They are important pollinators of wild and crop plants (Watmough 1973; McGuire 1999; Hogendoorn et al. 2000) and are reported to be more efcient than honey bees in pollinat- ing passion fower (Roubik 1995). Carpenter bees are an interesting group as they represent the entire spectrum of social organisation with a large number of solitary species, a few communal species and even fewer that are primitively social (Gerling et al. 1983, 1989; Velthuis 1987; Stark 1992; Hogendoorn and Velthuis 1999; Steen and Schwarz 2000). Sociality has been described in 8–10 species (Gerling et al. 1989; Keasar 2010) and involves a dominant reproductive female sharing the nest with a related or unrelated subordi- nate female (Bonelli 1974; Gerling et al. 1983; Velthuis and Gerling 1983; Hogendoorn and Leys 1993). In the social species, all tasks such as maintenance, cell preparation, for- aging and provisioning are performed by the reproductive female, while the subordinate female guards the nest (Ger- ling and Hermann 1978). Voltinism (the number of brood produced over a lifetime) is known to depend on resource availability and climatic conditions (Gerling et al. 1983) and ranges from 1 to 4 in diferent species of carpenter bees (Bonelli 1974; Raju and Rao 2006). The large body sizes of carpenter bees also endow them with large eyes, a large brain, large fight muscles and excellent thermoregulatory abilities. Moreover, they are relatively long lived with life * Hema Somanathan hsomanathan@iisertvm.ac.in 1 IISER TVM Centre for Research and Education in Ecology and Evolution (ICREEE), School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram, Kerala, India