Brachygastra scutellaris, a honey wasp, is a Neotropical, swarm-founding species that is found in South America and has a medium-sized population of 100-1000 individuals per colony. It stores large amounts of nectar in its nest for the production of honey, and it was even found that at certain times of the year, the nectar is toxic to humans, as they will extract nectar from hallucinogenic plants, depending on the season.
Taxonomy and phylogenetics
Brachygastra scutellaris is a part of the family Vespidae and the subfamily Polistinae as well as the tribe Epiponini. As is characteristic of the Vespidae, B. scutellaris is a eusocial wasp, which refers to the complex organization of behavior defined by: living in groups, cooperative care of young, reproductive division of labor and reproductive castes and an overlap of generations. As part of the subfamily Polistinae, food is masticated and subsequently fed to their young. The larvae then regurgitate the masticated food in the form of a nutritious liquid, which is consumed by the adults. Furthermore, as part of the Epiponini tribe, B. scutellaris is observed to be a polygynous species with several queens, and it reproduces via swarming.
Close relatives of Brachygastra scutellaris include: B. azteca, B. lecheguana, and B. mellifica.
Description and identification
Brachygastra scutellaris can be identified by characteristics that are specific to the genus Brachygastra. These include a prominent and projecting scutellum which, coupled with the metanotum and propodeum, form a vertical and flat thorax. Furthermore, the first tergum (abdominal segment) is short and cap-shaped. The second tergum, due to its large size, will conceal any successive terga, which gives these wasps a short appearance.
Variation
On top of more yellow coloration to signify caste differences, B. scutellaris shows continuous variation in bodily coloration ranging from fully black and fully yellow. The most common form of the wasp is presented in a mostly yellow abdomen (scutellum and metanotum) lined with pale and narrow bands. This form is extensively seen throughout Peru. As one moves to British Guiana, Bolivia, Ecuador and Brazil, the distinct yellow coloration of B. scutellaris is observably reduced.
On the other side of the spectrum, fully black B. scutellaris individuals are observed in Brazil. Both fully black and fully yellow individuals are found in Colombia. Though displaying a wide range of bodily coloration, these different variations of B. scutellaris must necessarily be grouped into a single species, as there is a distinct lack of difference in form and structure.
Sex identification
Both male and female B. scutellaris can range from 5–9mm with a wing length range of 5–9mm as well. Coloration varies for both sexes based on geographic location and environmental influences; B. scutellaris can range from fully black to fully yellow and anything variation in-between. Female heads have curved antennae and a mandible with two types of teeth: 3 large and acute, and 2 that are low, rounded and blunt. Males present shorter antennae as well as male genitalia with paramere 2–3x as long as high. Male abdomens have large punctures separated with a rough surface of tergum 2 whereas females have small punctures and a smooth surface of tergum 2. Lastly, males are observed to present more yellow pigmentation than females.
Distribution and habitat
B. scutellaris is most commonly found in Bolivia, Costa Rica, and Peru ranging in altitudes from 175m–700m. It is most commonly found in humid and forested areas and more specifically, the Atlantic forest. The Atlantic Forest is a 4,000 km2 terrestrial biome along the Atlantic coast characterized by mostly tropical and subtropical rainforest and tropical and subtropical grasslands, savannas and shrub-lands. B. scutellaris has a similar distribution to relatives B. smithii and B. augusti, though it does not spread into Paraguay and Argentina.
Wasps of the genus Brachygastra create nests in trees. Its composition varies between short chips or fibers that eventually form a brown and brittle home. Their nests are seemingly without order, often arranged without pattern and with a varying number of entrances. While the primary comb is attached to the tree, it acts as an anchor to all subsequent, secondary combs, which can, as well, be orderly or chaotically constructed.