A research team from Uppsala University has identified a significant gene responsible for sex determination in bees and ants, shedding light on the genetic mechanisms that govern these processes. Published on November 10, 2025, in the journal PLOS Biology, this study marks a crucial advancement in understanding how different insect species develop as male or female.
Most living organisms exhibit two biological sexes, with genetic exchange between males and females being essential for survival. In humans, sex is determined by the presence of X and Y chromosomes, where individuals with XY chromosomes become male and those with XX become female. This process is regulated by a gene on the Y chromosome known as SRY. In contrast, many insects, including bees, wasps, and ants, follow a haplodiploidy system, where fertilized eggs develop into females and unfertilized eggs turn into males.
For over two decades, researchers have recognized that the gene csd plays a critical role in the sex determination of honeybees. Females develop when two different versions of this gene are present, while males arise from a single version. Until now, it remained uncertain whether other bee species shared this genetic mechanism.
To answer this question, Matthew Webster and his research team at Uppsala University sequenced the genome of the red mason bee, or Osmia bicornis, commonly found in garden bee hotels across Europe. By analyzing hundreds of nests, they identified unusually large males that possessed two identical copies of the sex-determining gene. This comparison allowed them to locate the specific gene responsible for sex determination in this species.
Surprisingly, the gene they identified, ANTSR, is the same one that has been shown to control sex in a specific ant species. ANTSR is classified as a long non-coding RNA gene, meaning it does not translate into a protein. Instead, it functions as a switch that initiates male or female developmental pathways based on the number of gene copies present.
Webster expressed his astonishment at the discovery: “This is really surprising because it means ANTSR could be the main sex-determining gene used by more than 150,000 species of bees, wasps, and ants.” The research team acknowledged that significant questions remain, particularly regarding how variations in this gene generate the signals that dictate male or female development. The reason why honeybees utilize a different sex-determining gene also remains unclear.
This discovery is pivotal for researchers striving to comprehend the evolution of sex determination systems across bees and ants, as well as the underlying molecular mechanisms of the haplodiploid system. Understanding these systems is essential for maintaining healthy populations, particularly in light of ongoing concerns regarding bee conservation and biodiversity.
The implications of this research extend beyond academia, potentially informing breeding programs and conservation efforts for these vital pollinators. Insights into the genetics of reproduction in bees could be instrumental in ensuring the stability and health of ecosystems that rely on their pollination services.
In conclusion, the identification of the ANTSR gene as a key player in sex determination represents a significant step forward in entomological research, promising to unlock further insights into the complex world of insect genetics.
