Researchers from the University of Liège, as part of the FreezeBEE project, have achieved a promising breakthrough in bee insemination. For the first time, an attempt using frozen semen without the addition of antibiotics has resulted in the production of female brood, with a viability rate equivalent to traditional methods. This discovery paves the way for new opportunities in bee conservation and agriculture.
The conservation of bees is essential for ensuring crop pollination and maintaining biodiversity. With this in mind, a team of researchers from the University of Liège has developed an innovative protocol for the cryopreservation of drone semen, the male equivalent of bees. Their study presents a simplified, antibiotic-free method, creating new possibilities for apiculture and bee conservation.
"Bees play a crucial role in the ecosystem and agriculture," explains Sophie Egyptien , a doctoral researcher at ULiège and the lead author of the article. "Unfortunately, their populations are declining in many regions of the world. The conservation of their genetic material, such as drone semen, is a key strategy to preserve biodiversity and support breeding programmes." Cryopreservation is a research area with very few scientific teams working on it globally. It not only allows for the preservation of valuable genetic lines but also helps overcome restrictions related to the international transport of live animals.
A simple, antibiotic-free protocol
Since the 1980s, several freezing protocols have been developed, but with varying results. These protocols were often complex, involving multiple steps and the use of antibiotics to limit microbial contamination, and did not always produce reproducible outcomes. The ULiège team tackled this challenge with a more accessible approach: a simple dilution of the semen in a medium containing cryoprotectants. Cryoprotectants are substances used to protect cells, tissues, or organisms from damage caused by freezing and thawing. When an organism or cell is exposed to very low temperatures, ice crystal formation can damage cellular structures and lead to their destruction. Cryoprotectants, such as egg yolk, help mitigate these effects by reducing ice formation and maintaining cell integrity.
"Our method has demonstrated that, despite a 37% loss of sperm viability during freezing, five out of the eight queens inseminated with this frozen semen produced female brood," says Stefan Deleuze , Professor and Researcher at ULiège. "These results are comparable to those obtained with fresh semen in our study, which is very encouraging!"
This advancement offers several opportunities for apiculture. It enables the preservation of valuable genetic lines, allowing beekeepers to freeze the semen of disease-resistant or locally adapted strains. It also helps mitigate health risks by avoiding the transport of live bees, thereby reducing the spread of pathogens. Moreover, it supports breeding programmes by facilitating access to greater genetic diversity, even during reduced breeding periods, thereby strengthening the sustainability of colonies and preserving ecological balance.
A pioneering achievement in Belgium
This study is the first in Belgium to demonstrate that frozen semen can be used to produce female bees. To ensure a thorough analysis of their samples, the team benefited from the access to advanced microscopy facilities, which allowed for precise analysis of sperm quality.
"These results are promising, but we know that improvements are needed. We will now focus on optimising cryoprotectant concentrations and reducing viability losses," explains Stefan Deleuze. "We also need to assess the long-term impact on queen survival and female brood production."
This simple, antibiotic-free protocol marks a significant step towards bee preservation and global food security. With continued efforts, this technology could transform apicultural practices and help protect a vital pollinator within our ecosystem.
