A duo of French scientists is investigating the effects of ionizing radiation on pollinators. Their research takes us to Fukushima, Japan—the site of the infamous nuclear disaster in 2011. The objective is to understand how radioactivity can impact the cognitive abilities of these indispensable insects.
Why Are Such Studies Necessary?
First and foremost, pollinators like bees and other hornets possess numerous cognitive abilities that allow them to navigate their environment and recognize colors. It is known that pollution and other human-origin substances can disrupt the cognition of these insects. But what about radioactivity? This topic was explored in an article published by CNRS Le Journal on May 16, 2025.
The magazine interviewed Olivier Armant from the Ecology and Ecotoxicology of Radionuclides laboratory of the Nuclear Safety Authority and Radiation Protection (ASNR), and Mathieu Lihoreau, an ethologist at the Animal Cognition Research Center (CRCA) of the Integrative Biology Center in Toulouse (CBI). Armant is exploring the ecological effects of ionizing radiation, particularly on the flora and fauna of the contaminated area of Fukushima. On the other hand, Lihoreau is fascinated by bee intelligence and the factors that can alter this intelligence.
Today, the two researchers are collaborating with Japan through a system developed with the Toulouse-based startup BeeGuard. This involves a connected hive concept that enables real-time monitoring of the biological activity of certain bee species in a radioactive context. For the scientists, this research can provide insights into the learning and memory capabilities of bees and could also prove useful in ecotoxicology . According to Mathieu Lihoreau, “If bees show learning deficits in certain areas, there is a problem.”
Initial Findings Raise Concerns
For this duo, radioactive residues present in nectar may impair the cognitive capacities of bees. For instance, they might struggle to associate a reward with a particular color (or scent). As a result, these insects could end up pollinating flowers from different species rather than focusing on just one, thereby compromising the correct transfer of pollen between plants. In the long term, this behavior could jeopardize the survival of colonies and, more generally, the pollination service essential for ecosystem balance . This remains a hypothesis, yet similar conclusions have been drawn in areas with pesticide presence.
After several tests in the Toulouse region, the connected hive was deployed in the contaminated area of Fukushima during two field actions in 2023 and 2024 . Sites were selected based on the gradient of soil contamination by cesium-137, and local hornets were included in the cognitive study. The hive features a Y-shaped maze with two paths lit by different colored LEDs. Only one of these colors offers a reward of sweetened water. Experts note that a healthy bee needs about ten trials to find the correct path.
While the results of the study have not yet been published in a scientific journal, the two French researchers are already worried. They have reported a decline in cognitive performance in the contaminated area of Fukushima. However, while correlations exist, there is currently no evidence of a causal link involving radioactive contamination. Nonetheless, since the area is now uninhabited, this cognitive decline cannot be attributed to pesticide exposure.