Source: Fundação de Amparo à Pesquisa do Estado de São Paulo
The Brazilian stingless bee Tetragonisca angustula (jataí in Portuguese) deploys a different strategy for defending its nests from other social insect species. In addition to posting sentinels at the nest entrance, as do most social insects, colonies of this species also have guards that hover near the entrance all the time.
A study by researchers in the Department of Entomology and Acarology of the University of São Paulo's Luiz de Queiroz College of Agriculture (ESALQ-USP) in Brazil and the University of Sussex in the United Kingdom found that hovering guardian bees position themselves near the nest entrance in a nonrandom manner.
They tend to hover in even numbers on both sides of the entrance. This distribution enables them to detect and intercept intruders more rapidly before they reach the nest and begin an attack. This strategy improves nest vigilance, according to the researchers.
The study resulted from a project supported by São Paulo Research Foundation -- FAPESP and was published in the journal Behavioral Ecology.
"We observed that the guards of this stingless bee species coordinate their nest vigilance strategy against robber bees and possible predators," said Denise de Araujo Alves, a postdoctoral researcher at ESALQ-USP and one of the authors of the study.
The researchers filmed and analyzed the behavior of 15 colonies of T. angustula stingless bees (Meliponini). The species is considered only mildly aggressive compared to most stingless bees, but its guards are especially defensive toward the obligate robber bee Lestrimelitta limao, its main natural enemy and a potential destroyer of its nests.