Sharing a house involves communicating important information to maintain the organisation. For example, when the food stock in our homes is over, we make a list and go to the supermarket, or we might have a vegetable garden and ask someone to help us gather the food we need for the week. All these tasks involve communication. But how do stingless bee workers organise food gatherings? How do they make sure the hive has enough supply? Bees certainly do not make lists but have interesting ways of telling their nestmates that good flowers await them outside.

Author:  Ana Paula Cipriano

Leia em Português

Social bees can live in nests with hundreds or thousands of other bees, making the organisation and coordination of their activities very important. Three main tasks can benefit from good communication between nestmates: looking for a new spot to build a nest, combating intruders, and food gathering. Going outside to find a flower alone can be a challenge for an individual bee, but if she gets tips on where to find good food sources, the task becomes easier. 

Honeybees developed a famous way of sharing information about good quality flowers with their nestmates: they dance. The waggle dance informs the distance and the direction of the food source, which can make the process of obtaining nectar and pollen more productive. But, how about the stingless bees? Do they also dance?

With more than 550 species of stingless bees across the Neotropics, researchers still have much to learn about their communication. However, for decades the secrets of how native bees share information within the nest have been investigated, especially in Brazil. The basic scientific methodology for studying food source communication involves training bees to visit an artificial flower that provides sugar water, similar to what people do as a hobby with hummingbirds

When bees start visiting this plastic flower, researchers move it some meters away from the original position and study the reaction of the bees according to the species. Some of them, such as Trigona spinipes (Arapuá) and Scaptotrigona postica (Mandaguari), for example, can dominate a food source with many nestmates, indicating their mass-communication abilities.

But what happens inside the nest? How do these stingless bees communicate their findings? The answer is: no, they do not dance the same way as honeybees. But they can be as effective as them, or even more, in sharing information and ensuring the hives get enough food. Usually, after finding a good food source, a forager returns and starts to run close to the nest entrance in what are called “zigzag” or “jostling” runs. Basically, this experienced bee performs an excitatory state and can bump into other bees, informing them that there is good food outside and they should go and find it. 

During these runs, the demonstrator bee also shares some food with the nestmates in a behaviour called trophallaxis. The scent of the food being transferred can also help guide nestmates to the flowers. Interestingly, it was shown for some Melipona species that while this experienced bee is giving food to the others, she is also shaking her thoracic muscles, and depending on how good the sugar collected was, she vibrates more intensely. Unlike humans, bees do not have a way to give 5 stars to great food on an app, but they have found interesting ways of recommending good quality food. 

Due to their diversity, stingless bees exhibit a variety of communication strategies, and some species can guide nestmates to a specific food source, while others communicate just some aspects of the flowers, such as the smell and direction. It is still an enigma how some stingless bees communicate the location of a visited flower.  

At the same time, part of this big question is being solved year after year by researchers. One specific way that some stingless bees guide their nestmates is by chemical trails. Experienced foragers land on leaves, branches, and other surfaces that are in the path between the nest and the food source and deposit pheromones that guide other bees. Arapuá bees, for example, can use this amazing strategy. 

However, even after studying the chemical trails, the buzzing vibrations that foragers execute, and the zigzag runs, many questions remain open about stingless bee communication. Imagine a meliponary with several nests, or even a forest with many different smells and insects, how does a forager identify the beginning of a pheromone trail and keep following it until the flower? 

Living in one of the most biodiverse spots in the world, it is still a mystery how stingless bees use scents and coordinated movements to guarantee that their nests will have enough food. In this context, it highlights the importance of preserving our natural environments, which are full of incredible native species such as stingless bees, to ensure that many other interesting, yet unknown, behaviours will be discovered.