Magnetic particles found across most bee species; study reveals
Previous work on magnetoreception in bees had focused almost entirely on five species, including the western honey bee and several bumblebee and stingless bee species. That left a major gap because the vast majority of the world’s bees live solitary lives rather than in colonies.To investigate further, the researchers measured magnetic properties in 138 bee specimens representing 96 species from six different bee families. They also examined 47 insects outside the bee lineage for comparison. Their analysis detected ferromagnetic particles in 74 of the 96 bee species examined, with similar signals appearing in some wasps, flies and beetles as well. According to the study, this broad distribution suggests the biological basis for magnetoreception may have appeared before bees evolved as a distinct group.
Bee magnetic sensing appears across different species and lifestyles
The results did not fit the long-standing assumption that magnetic sensing might mainly belong to highly social bees. Instead, the researchers identified magnetic particles in solitary, eusocial and cleptoparasitic bees, as well as in both males and females. Species that nest underground, inside cavities and in plant stems all showed evidence of ferromagnetism. Larger bees generally carried stronger magnetic signals, while cavity-nesting species tended to show higher levels of magnetisation than ground- or stem-nesting bees. Eusocial bees also displayed stronger magnetic characteristics in some measurements, although the trait itself was not limited to social species.According to the study, for evolutionary patterns but no clear phylogenetic signal was found. Closely related species did not consistently share the same magnetic characteristics, leading the team to suggest that this form of magnetoreception probably predates the origin of bees rather than emerging within a particular branch of the group.
Where are magnetic particles found inside bees
As per the study, it explored where these particles are located inside the insects. Earlier research had pointed to antennae, wings or the abdomen in a small number of bee species. This broader investigation painted a different picture. When individual body regions were analysed separately, the middle section of the body, known as the mesosoma, generally contained the greatest share of magnetic material. The abdomen also carried strong signals, while the head typically showed weaker ones. Magnetic particles were usually spread across more than one body region rather than being confined to a single location.This distribution is consistent with one proposed mechanism of magnetoreception involving tiny particles of magnetite, an iron oxide mineral capable of responding to magnetic fields. At the same time, they note that other mechanisms, including those involving light-sensitive proteins, have also been proposed for insects.
Magnetic particles alone do not prove bees use a magnetic compass
Although the findings considerably expand the number of bee species associated with magnetic particles, the researchers are careful about what the results mean. Their work measured ferromagnetic particles rather than behaviour. The presence of those particles suggests many species may have the biological structures needed for magnetoreception, yet it does not demonstrate that the insects actively rely on Earth’s magnetic field while navigating. Behavioural experiments will still be needed to establish whether these magnetic structures function as an internal compass under natural conditions.The study broadens the picture of how widespread this hidden feature may be. Rather than being restricted to a few familiar social bees, magnetic particles appear across a wide range of bee species with very different lifestyles, leaving scientists with a new set of questions about how these insects find their way through the world
