Synoeca cyanea

The hierarchy of S. cyanea is based on physiology, specifically ovarian development. Wasps containing undeveloped filamentous ovarioles, slightly developed oocytes, or some mature oocytes are considered workers and intermediates. Wasps with well-developed and longer ovarioles with mature oocytes become queens. The number of queens in the colony determines the development of a queen’s ovaries. If there are more queens present, the ovaries are at a lower degree of development. One benefit to this is that as a swarming insect, queens with smaller abdomens are able to fly more easily than queens with larger abdomens. This makes the queen less susceptible to predators.[2]

Foraging activity for the swarm-founding wasp S. cyanea begins early in the morning and stops in the evening. During the hottest hours of the day, activity of the wasps is highest. In addition to temperature, S. cyanea increase their activity with decreased levels of humidity and heightened intensities of light. While foraging, the wasps collect water for temperature control, wood pulp for building and repairing the nest, sugary substances for both the larvae and adults and finally animal protein for larvae.[3]

Following damage by rain to the nest, S. cyanea will seal a leak of water with their mouth-pieces. Individuals begin by suctioning the water from the wall of the nest and then finish by expelling the water to the exterior of the colony. The hole is then repaired using wood pulp.[3]

In S. cyanea, discrimination between the queen and workers is often not determined by morphology, but by physiology. Young females in the colony can develop ovaries at different points in the cycle, so castes must be determined by the adult wasps rather than at the larval stage. Often, adult wasps will manipulate young females and suppress their ovaries because a wasp becomes a queen once she has mated. The number of queens allowed in a nest often fluctuates. When queen repopulation is not needed workerpolicing helps to prevent female egg-layers through egg-eating and aggressive behaviors.[2]

The wasps forage for sugary substances to feed to both larvae and adult wasps.[3] Additionally, necrophagy is a common practice for swarm-founding Neotropical bees and wasps, and one species that practices this is S. cyanea.[8] S. cyanea feed larvae the animal proteins collected.[3] The wasps are predators of the coffee-leaf-miner, Leucoptera coffeella.[9]

Characteristic to the genus, S. cyanea will sound an alarm when disturbed.[9] This sound is made when the wasps scrape their mandibles on the carton of their nest.[10] In addition, as one of the most aggressive social wasps, S. cyanea often will bite and sting when threatened. Their barbed sting often remains in the skin as the wasp pulls away.[11]

S. cyanea venom is strong enough to cause haemolytic activity. Rhabdomyolysis and hemorrhage may also occur. In mice, abdominal spasms, ataxia, defecation, dyspnoea, hyperactivity, hypoactivity, sweating, and throes were observed following venom injection. S. cyanea venom also contains some antibacterial activity.[9]

Human accidents with wasps can occur one of two ways. Either a human may receive no more than one or two stings, or a swarm may attack a human. Symptoms following the attack can range from inflammatory reactions to severe allergic reactions resulting in anaphylactic shock. In some cases, death may occur following several bites and a large amount of venom injection; however, a wasp sting typically will not produce a reaction more severe than local symptoms that affect only the skin.[9]

In Brazil, the fruit fly Zaprionus indianus is a common pest species that inflicts damage to multiple types of fruit trees. Since S. cyanea may obtain many nutrients from these fruit trees, researchers have observed the predatory nature of these wasps on Z. indianus. When S. cyanea detect the fruit fly larvae, they soften, remove, and transport them back to the colony. For this reason, many fruit farmers consider S. cyanea a prospective candidate for use in pest management.[12]