Yellow-banded Polybia Wasp

Appearance

"P. occidentalis" is a black and yellow wasp - a black base with few yellow stripes on its abdomen. Its wings are thin and the thorax is attached to the abdomen by a long, thin petiole. Workers have a mean dry weight ranging from 3.80 to 6.71 mg. Its costal length ranges from 3.6 to 4.7 mm. Queen wasps are differentiated from workers because they have visibly larger ovaries, which are filled with eggs. Males are differentiated from workers and queens due to their visible testes.

Distribution

"P. occidentalis" can be found from Mexico to northern Argentina. This species of wasp is common in Costa Rica and Brazil. live in neotropic areas that consist of tropical forests with strong wet-dry seasonality.

These wasps nest in neotropic areas to have the appropriate resources for building and gathering prey in the wet season and surviving with these resources through the dry season. Neotropic environments are beneficial for swarm-founding colonies. They usually settle where large carbohydrate sources are available. "P. occidentalis" wasps build their nests in low areas and find shelter in trees, bushes, hedges, and even buildings.

Reproduction

Nests are made up of several stacked combs, each covered with an envelope. They are made up of wood pulp and water. The envelope of one comb provides the support on which to build the next comb. The shape of the nest is called phragmocyttarous, which means that combs are attached to the inside surface of the nest laterally. Usually, the number of cones is appropriate for the number of wasps in the nest. Nests are about 10–25 cm long. They are built in neotropic areas in shrubs and trees in pastures, hedgerows, forest edges, and on and around buildings. The nests are usually built in the morning. They are built by the workers through a division of labor; they are social wasps. The nests are built top to bottom to form a shape of a teardrop.

Food

"P. occidentalis" feeds on insect prey, carbohydrate sources, and nectar found in nearby locations. This species is one of the few wasps that collects nectar. After collecting the nectar, they then store it in empty comb shells.

Predators

Usually, predation occurs away from the nest. Mantids and robber flies prey on foragers who are trying to gather resources. Because there is less defense away from the nest, foragers are more likely to be prey for these predators. Also, nests are attacked by ants or vertebrates such as white-faced capuchin monkeys. This can lead to a loss of brood and it can destroy a nest. One ant attack cannot exterminate an entire colony, but it does cause a great deal of trouble for the colony because the colony must move locations. The workers attempt to rebuild the nest if possible. Also, the colony decrease in size and needs energy for the queens to reproduce. After more than one attack by the ants, though, the risk is higher for extermination of the entire colony.

Defense

When the colony feels harmed, they defend themselves using two steps. The first is the alarm recruitment when the nest is jarred. This cues many adult wasps to move to the outside surface of the nest to protect the nest and defend the entrance from the predators, for example from ants covering the nest or a bird trying to enter. The next step is to attack the predator if necessary. Because wasps react to the odor of venom, they use this as one cue to attack. If the odor of the predator is strong enough, then the wasps will attack. These wasps will try to sting the intruder by flying rapidly and directly toward the intruder with a great force. They most likely attack if the intruder has a specific visual stimulus, such as a dark color, as opposed to whether or not it is moving, as in "Vespula". However, not all attacks are rapid and direct. The presence of alarm pheromone, another odor secretion from the predator, makes wasps fly, hover, land, and then inspect the odor source. This mechanism reduces the need for attack.

Evolution

Overall, the colonies last for a year, as they have an annual cycle. To start the cycle, the workers and the queens build the nest and reproduce, respectively, at the beginning of the dry season. Throughout the wet season, males are produced first and then future queens are produced. Because the workers are the colony founders and they expend much energy in building the colonies, they tend to have a higher mortality rate, but workers in older, larger colonies live longer because they have more coworkers with which to build the nest. Therefore, they do not exert as much energy in building the nest as they would if they had been in a colony with fewer workers.