Solitary' But 'Sociable' Bees: UniPadova's Discovery

We are now well aware of the importance of the honey bee, which plays a fundamental role as a pollinator. Thanks to this valuable activity, it is vital for the preservation of biodiversity and for the production of primary goods for humans, such as fruit, vegetables and meat. Like other pollinator species (butterflies and midges), their existence is under severe threat due to climate change, disease and the massive and reckless use of pesticides in agri-food production. In previous articles we have also seen what we can do concretely, even in our own small way, to protect bees from the danger of extinction and help beekeepers in their hard work to protect bees. Although scientific and public attention is focused on honeybees, an equally crucial role is played by the more than 20,000 species existing of wild bees.

However, unlike honeybees, there is still limited knowledge about the biology of solitary bee species, as well as the interactions between pollinator species and the causes of their disappearance. It was precisely on these fascinating topics that the research conducted by researchers from the University of Padua, Prof. Lars Chittka, Dr. Ana Híjar-Islas (Queen Mary University of London, London, UK) and project leader Dr. Olli Loukola (University of Oulu, Oulu, Finland), focused. Through field work, they studied how solitary bees use information from different bee species with which they share the same environment to build their nests.

Dr. Elia Gatto, a researcher in the Department of General Psychology at the University of Padua, explains: 'Most studies on bees concern the social species that live in hives, where a queen resides together with the workers. What is not yet known is that most of the wild bee species are solitary, i.e. "single mothers" in which each female individual builds her own nest, as well as being among the main pollinator species. Although solitary bee species take care of their own nests, it is interesting that such nests are found in aggregations, often by several different bee species residing in close proximity to each other.

In our study, we find that before choosing where to build their nest, these bees carefully inspect other nests for clues that signal the presence of pests, to ensure that their own brood will not fall prey to these pests. If bees notice such signs, they tend to establish their nesting sites further away. On the other hand, if the area appears to be safe, they tend to build nests nearby. Moreover, solitary bees appear surprisingly intelligent when making these kinds of assessments. During inspections, they not only notice signs indicating the presence of pests, but also pay attention to any nearby signs that could be related to the pests themselves.

In the study, abstract symbols (circles or triangles) were placed next to parasitised nests, discovering how bees remember the association between symbols and the state of the nest visited, and consequently avoid symbols indicating the presence of parasites. These results reveal how, although these solitary bees have no real social life, they are incredibly intelligent and attentive to surrounding information, studying and interpreting the activities of other species sharing the same environment. The study was published in the prestigious journal Animal Biology as an important landmark in the study of these still little-known species and in raising awareness of their importance to the environment and to humans.