Increasing trade in wild bee cocoons could disrupt pollinator communities
Recently, a third misplaced conservation practice has emerged: people thought of filling up themselves bee hotels with cocoons to control both the species and the occupancy rate. To do so, online companies selling wild bee cocoons for bee hotels have arisen (Fig. 1). Before this new trend, few bee species was reared and commercialized for trap nests mostly to pollinate crops (Aizen et al. 2020) and the commercialization of wild bees was restricted to professional agricultural practices. However, these companies now routinely sell cocoons of Osmia species (mason bees) and Megachile(leafcutter bees) to anyone wanting to purchase wild bees (e.g., https://crownbees.com/; https://masonbeesforsale.com/, among others). Overall, the potential invasiveness of insects has been associated to their global commercial success (Gippet & Bertelsmeier 2021) and trade volumes (Bang & Courchamp 2021). Therefore, in October 2021, using the keywords “buy bee cocoons”, “buy wild bees” and “wild bees for sale” we searched in Google in seven languages (English, French, German, Italian, Russian, Spanish, and Chinese) all website selling wild bee cocoons online. We found 42 websites selling cocoons for a total of eight different species (Supplementary material S1). While some sellers appeared to restrict their shipping to native species or those from a few neighbouring countries, it was very easy to buy cocoons from another continent online. For example, in June 2021, a package shipped from France to Seattle (USA), was seized by the biosecurity service of New Caledonia, a French tropical archipelago. Inside the package, bamboo twigs containing 23 lived cocoons of wild bees (Osmia sp. ) with two recently emerged females (H. Jourdan, pers. obs .).
By promoting the trade of wild bees, we believe that companies selling bee cocoons create a window of opportunities for ecological disturbances inside and outside of their native area (Fig. 1). The unregulated trade of insects worldwide has already caused considerable damages not only to ecosystems but also to the economy (Diagne et al. 2021) and is predicted to become increasingly problematic (Bang & Courchamp 2021). This practice is also highly problematic as it constitutes a potentially very high propagule pressure of introduced species (repeated introductions of many individuals in many places). Bees emerging from cocoons can also compete with native bees for floral resources. For example, Osmia cornifrons a species whose cocoons are sold online, is exotic in the United States and has been recently associated to the strong decline of six native mason bee species either due to resources competition, pathogen spillover or both (LeCroy et al.2020). As Osmia cornifrons , all bee species currently sold online are Megachillidae which is also the most represented bee family among the exotic and invasive bee species recorded worldwide (Russo 2016). Buying bees online could also arise the risk of transmitting diseases (Aizen et al. 2020). Parasites and diseases are widespread in animal husbandry, and even when all possible precautions are taken, the spillover hazard can never reach zero. For example, Hedtke et al.(2015), demonstrated that O. cornifrons transported fungi from its native range Japan to the United States. Hence, we believe that the trade of bee cocoons online is also a misplaced conservation practice as it a) misinforms the public and blur their perception of the importance of wild bees especially the native ones, b) leads to a misallocation of resources: instead of protecting the local populations, people invest funds in reared species, and c) potentially harms biodiversity by fostering the spread of exotic species, increasing competition for floral resources and favouring potential pathogens spillover.
Conclusion :
Misplaced conservation practices have multiplied in recent years (Fordet al. 2021), mainly through the rapid dissemination of simplified information, putting ecological knowledge and its complexity aside. The first step towards more appropriate measures is to inform companies, citizens, and decision-makers about the complexity of species interactions and orientate their choices based on scientifically sound arguments. Research in conservation ecology should continue to be developed to offer comprehensive tools to whom want to set up conservation practices. For bees, ensuring sufficient resources by promoting local and native flowering plants, preserving, and protecting nesting and reproductive sites, is better than introducing more individuals (especially without considering which species). Removing current threats on pollinators, such as the agrochemical use, appears more efficient and more logical than trying to boost existing, threatened populations. Finally, it is still possible to buy or build a bee hotel with substrates adapted to local populations while avoiding the establishment of non-native bee species. These have the added benefit to educate people involved about ecological concepts as well as to reconnect them with nature, two aspects that are likely pursued by those willing to help biodiversity in general, and bees in particular.
Acknowledgements : We sincerely thanks Sherry Stanbury for English editing. We also deeply thanks Franck Courchamp, Boris Leroy, Bertrand Schatz and Hervé Jourdan for their help on previous versions of this article.