Vulture Bees

Vulture bees are a small group of closely related stingless bees that are obligate necrophages. This means that their diet consists of mostly carrion. So, these bees don't collect pollen and instead collect their protein from carrion or other animal protein source instead. Vulture bees may have evolved to collect animal protein instead of pollen because it is easier to obtain energy from meat (Gruter, 2021). So, these bees have developed specialized behaviours and processes in order to collect, process, and store collected carrion.

I would like to talk about the process of these bees collecting and processing animal protein, sugars for carbohydrates, and other facts that you may not know about them!

Vulture bee species

There are three bee species that are classified as vulture bees: Trigona crassipes, Trigona hypogea, and Trigona necrophaga (Roubik,1982). All three of these bees are known as stingless bees, which means their sting is vestigial and cannot sting for defense. These bees are all found in South America. The most studied bee out of these is Trigona hypogea.

"File:Stingless Bees (Trigona sp. ?) (8437427653).jpg" by Bernard DUPONT from FRANCE is licensed under CC BY-SA 2.0. These bees have not been identified, so I am unsure the exact Trigona species.

Collection of protein and carbohydrates

Bees, just like us, need to eat fat, protein, and carbohydrates. Bees also need to collect fat, protein, and carbohydrates for their young. Let's see how vulture bees meet these dietary requirements!

Vulture bees are bees that are no longer palynivores (aka. bees that consume pollen for protein), they are considered obligate necrophages as they consume mostly animal protein (Roubik, 1982). These bees have been observed collecting animal protein from various dead vertebrates (Roubik, 1982; Noll et al., 1996). They collect animal protein by chewing on the meat using their mandibles to liquify it. Vulture bees have strong mandibles with 5 large protrusions (aka 'teeth') to help cut the protein from the carcass. Vulture bees also have mouthpart secretions to pre-digest the animal protein (Roubik, 1982). The secretions from their mouthparts keep ants and flies away from carrion, so vulture bees can monopolize a corpse (Noll, 1997). Vulture bees will collect most of the animal protein within their crop (which is like a pre-stomach as it doesn't completely digest consumed food) to carry it back to their nest for storage and further processing (Noll et al., 1996).

Animal protein does not provide a good source of carbohydrates. So, vulture bees need to forage somewhere else for this resource. Bees usually collect sugary flower nectar to fulfill their carbohydrate requirements. Two of the vulture bees,T. hypogea and T. necrophaga, collect their carbohydrates from fruit and sugar-rich liquid from extra-floral nectaries (Noll et al., 1996). Extra-floral nectaries are found on stems, leaves, or plant structures other than flowers. Vulture bees do not collect nectar from flowers which means they do not pollinate as they are never in contact with pollen grains contained in the flowers (Noll et al., 1996).

Storage and processing of food in the hive

Vulture bees, like honey bees, are eusocial and have a hive. Vulture bees are very different from honey bees however. These three bee species are known to create differently shaped nest structures like spiral brood comb. Vulture bees typically nest in wood, although Trigona hypogea has been recorded nesting in the ground in select areas (Gruter, 2021).

The rest of the information in this section is based on Trigona hypogea. This is because Trigona necrophaga and Trigona crassipes have fewer available research papers written about them, so it is difficult to say what goes on in within the hive.

Trigona hypogea stores its collected animal protein in storage pots within the hive (Noll et al., 1996). These pots are usually made of wax. The animal proteins stored in the these pots are mixed with honey by the bees. The mixture of protein, honey, and enzymes from the bee's crop and mouthparts are then left to mature for about 2 weeks (Noll et al., 1996). This maturation phase allows the protein within the pots to break down more and become more easily digestable. When the protein is first put in the pots, it looks like chewed meat or carrion. After the 2 week maturation period, the protein in these pots looks like a pale yellow paste (Noll et al., 1996).

Trigona hypogea also stores its collected sugars in storage pots within the hive. The sugary liquids from fruits and extra-floral nectaries vulture bees collected are contained within their own storage pots (Noll et al., 1996). Once sugary liquids are collected from the plant and contained within the vulture bee's crop, it is now considered honey and is directly deposited into its own dedicated storage pot by the bees. Other than secretions from the crop, the honey is not processed further which is different from honey bees (Noll et al., 1996).

Other fun facts about vulture bees

Here is a short list of facts about these bees that you may not have heard!

• These bees have an acidic gut which helps them obtain their nutrition from animal protein and stay healthy (Figueroa et al., 2021).

• These bees have been seen collecting protein from a wide variety of carrion including, but not limited to, dead lizards, toads, birds, rats, snakes, (Noll, 1997; ).

• These bees do not make excess honey like honey bees.

• At least one researcher has tasted the honey created by these bees and described the honey as a "pleasant tasting-smelling honey-like liquid" (Noll et al., 1996).

• The honey these bees produce does not go through an evaporation step, so the honey is much more watery compared to honey from honey bees.

References

Figueroa, L. L., Maccaro, J. J., Krichilsky, E., Yanega, D., & McFrederick, Q. S. (2021). Why did the bee eat the chicken? Symbiont Gain, loss, and retention in the vulture bee microbiome. MBio, 12(6). https://doi.org/10.1128/mbio.02317-21

Gruter, C. (2021). Stingless Bees: Their behaviour, ecology and evolution. Springer.

Noll, F. B., Zucchi, R., Jorge, J. A., & Mateus, S. (1996). Food Collection and Maturation in the Necrophagous Stingless Bee, Trigona hypogea (Hymenoptera: Meliponinae). Journal of the Kansas Entomological Society, 69(4), 287–293.

Noll FB (1997) Foraging behavior on carcasses in the nectrophagic bee Trigona hypogea

(Hymenoptera: Apidae). J Insect Behav 10:463–467

Roubik, D. W. (1982). Obligate necrophagy in a social bee. Science, 217(4564), 1059–1060. https://doi.org/10.1126/science.217.4564.1059