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Solitary bees learn from their neighbours

A new study has found that mason bees, which are a type of solitary bee, use interspecies social information when selecting a nest hole. Mason bees observe and remember the nesting preferences and success of previous nesting species. They copy the previous nesting species if their nests show themselves to be successful. If the nesting of the previous nesting species shows itself to be a failure, the female mason bees chose another nesting hole.

 

For the first time, the study shows that bees living in the wild are also capable of flexible decision-making when choosing a nesting place. Even though the bees nest alone, they constantly monitor their surroundings and make good use of the choices made by others and the results obtained. By doing so, they save time and avoid risks. A similar strategy of ‘copy the successful / reject the failures’ has also been found among other species, such as the pied flycatcher.

The experimental study gave the bees the impression that the previous nesting species had chosen one of two adjacent nest holes. The only difference between the two nest holes was the symbol (circle and triangle) attached around them. The bee species that nested afterwards were offered two empty nest holes 20cm from the nest of the previous species, and these were also marked with a circle and triangle.

In addition, the nesting success of the previous nesting species was manipulated by drilling very small holes in the plug which is used by mason bees during the finishing phase to close their nesting holes. The holes mimicked the exit holes of tachinid flies and hymenopterans, which suggested that the nesting process was a failure. Some of the plugs were left intact to indicate successful nesting. The focus of interest was to examine the female's first choice of nesting place. The test chambers were equipped with an automatic data collection system, and at the end of the nesting season, the nests were collected and the data was analysed.

‘Social information is available to all, including non-social species. The use of social information enables the spread of new traditions both within and across species. This theory of selective social information use between species challenges the current theory of experimental evolution. ‘It predicts that the properties of the species using the information and the information source itself can either converge or divert depending on the perceived success of the information source,’ explains one of the authors of the study Docent Olli J. Loukola from the Department of Ecology and Genetics at the University of Oulu.

Little research on solitary bees

Social bees, such as the western honey bee and bumble bees, have been studied for a long time, and their behaviour and learning are already known to a large extent. However, about 85% of the world's bees (Apoidea) are solitary bees. In contrast to social bees, solitary bees nest alone. The females of these species are therefore always ‘single mothers’.

Relatively little behavioural research has been carried out on solitary bees and hardly anything is known about how they learn. They are known to be efficient pollinators of edible plants and they are happy to make their nests in insect hotels. One type of solitary bee is the Mason bee, which includes the species of the Osmia-genus. Around 10 different species of mason bee have been found in Finland.

The research experiments and material were collected in England from east London parks and cemeteries as well as nearby parts of Kent and Harpenden between 2015 and 2018.

A female mason bee choosing a nest hole. Photo:Olli Loukola

Article:
Loukola Olli J, Gatto Elia, Hijar-Islas Ana C, Chittka Lars: Selective interspecific information use in the nest choice of solitary bees, Animal Biology, DOI 10.1163/15707563-20191233

Article about pied flycatchers:
Loukola Olli J, Seppänen Janne-Tuomas, Krams Indrikis, Torvinen Satu, Forsman Jukka T: Observed fitness may affect niche overlap in competing species via selective social information use. The American Naturalist, DOI 10.1086/671815

Main photo: A female mason bee examines the nest of a previous nesting species. Photo: Olli Loukola

 

Last updated: 6.2.2020