The relationship between Osmia Conjuncta bees and European Grove snails
The Osmia Conjuncta bee, commonly known as the mason bee, is a species of bees named for their habit of using mud or other “masonry” products when constructing their nests. Their nests are typically made in naturally occurring gaps between stone cracks or small dark cavities.
Unlike the honey bees or bumblebees, the mason bee species are solitary, whereby every female is fertile and makes her own nest, and no worker bees exist. Contrary to honeybees, the mason bee is typically metallic blue or blue-black in colour. These bees are very effective pollinators known to work in cool or rainy weather. It is said that a couple of female mason bees can pollinate an entire apple tree.
A new study by biologists from McMaster University found that the Osmia Conjuncta bees found in North America use the empty shells of dead snails to incubate their offspring. This is a common occurrence in the mason bees found in Africa, Asia and Europe; however, little research has been done on the species living in North America.
The snail shells that provide a home for the mason bees come from the European Grove snails. These snails, commonly found in Europe, were introduced to North America. These snails are typically found in damp environments with lots of vegetation. They are very abundant in Hamilton and parts of Niagra. Although they are non-native, these snails are not known as being invasive because they tend only to eat dead materials, including dead leaves and other vegetation.
The researchers found that the abundance of shells in the study area allows the bees to choose optimal nurseries for their offspring, which helps boost their local populations. These findings show that the relationship between Osmia Conjuncta bees and European Grove snails will have a significant ecological impact in North America.
The shells from the grove snails come in various colours and sizes, and the researchers found that, on average, there are 11 suitable nesting shells per square metre. The Osmia Conjuncta bees will typically reject the largest and smallest shells as well as the darkest and lightest shells but are still left with a variety of shells to choose from.
They found that the shell choice may be influenced by how the colour affects its visibility to predators and by the temperature of the shell. This finding of 11 sustainable nesting shells is a significant number compared to other studies in North America, which have found that there is only one shell of the right size for bees to use per two square metres; therefore, Osmia Conjuncta bees and European grove snails thrive in conjunction with one another.
The abundance of snail shells available to the Osmia Conjuncta bees has created a much more robust population of bees in the study areas than is typically found elsewhere. What is interesting about the findings of this study is that it reveals the success of one species of wild bee while the broader population of wild native bees (like the honeybee) is under threat. Moreover, this research has been under-studied since 1937; it opens up a possibility to learn more about bees and their habitats and might even allow us to use the mason bees as the honeybee population recovers.
This study is also a fantastic example of the unique relationship between Osmia Conjuncta bees and European Grove snails. It also shows us how resourceful nature can be. The important factor for keeping these bee populations up is to discourage planting monocultures (which provide bees with only one nutrient source, which results in poor bee health), plant more native flowers and plant species, and eliminate the use of pesticides.