Researchers at Ruhr University Bochum in Germany have observed a striking behavior in male orchid bees: they collect specific scent molecules during the mating season and store them in a specialized sac on their hind legs. This accumulation appears to function as a self-made perfume, crafted by the bees themselves to help attract potential mates. The findings have been shared in current biology, contributing a fresh perspective to the understanding of bee courtship chemistry.
For years scientists noted that these bees gather fragrant compounds while preparing for reproduction, yet the purpose remained unclear. Some experts proposed that the scent might act as an attractant, drawing females closer, while others suggested it could serve as a signal to competitors about a male’s presence or quality. The study set out to resolve these questions by observing how scent production relates to mating outcomes.
The experimental setup involved raising a small, manageable colony of orchid bees under controlled conditions. In the experiment, a subset of males produced their own distinctive aromas, while another group did not carry such scents. Researchers then monitored female choice and recorded which male each female selected for mating, providing a clear link between odor production and reproductive success.
Across the observations, both scented and non-scented males demonstrated typical courtship sequences, and mating occurred with a total of 27 female bees, each engaging with a single chosen partner. Notably, only one female mated with an odorless male, but that individual appeared to have acquired a mix of scents by sampling odor compounds from other males, illustrating how aromatic resources can be traded or borrowed in the colony during courtship dynamics.
To determine whether the aroma directly influenced paternity, researchers conducted genetic analysis comparing the brood with the drones in the colony. The results indicated that the presence of the fragrance significantly increased a male’s likelihood of siring offspring, underscoring the pheromonal or olfactory role in females’ mating decisions. Importantly, the aroma influenced female behavior without altering the males’ own physiology or mating readiness, suggesting the scent’s primary function is to enhance attractiveness rather than to modify male performance.