A Not So Sweet Odor: Fungal Parasite Affects Bee Sense of Smell
- Diego Van de Laar
- Mar 22, 2023
- 3 min read
By: Diego Van de Laar
The end of winter is marked by many vibrant colours, from the blossoming of the trees to the blooming of the flowers. So it’s no surprise that bees, by being prolific pollinators, are important in ensuring spring comes around in full colour. Bees have an arsenal of cognitive and physiological tools that aid in the everyday activities of bees such as collecting pollen and nectar. These tools can be impaired by a plethora of environmental factors, one of which is Nosema ceranae, a fungus that invades the gut of bees after ingesting spores from contaminated pollen, water, or from close contact to infected bees. Tamara Gómez-Morachoand her team at Paul Sabatier University, France, wanted to explore how this fungus affects the ability for bees to learn through smelling.
Most animals can use their sense of smell to learn about their environment, and this affects their behaviour. For example, when us humans try a new food, and we don’t like it, we remember not only the taste of the food, but also the odour; the next time we smell that odour, we recognize it, associate it with the food we don’t like and know to stay away from it. Bees are no different from other animals, and they use the ability to learn by smelling in order to efficiently forage for nectar and pollen.
The ability to associate a certain odour with a reward (or punishment, as in the case of foods we dislike) using short term and long term memory is known as absolute learning, and is one method of olfactory (smelling) learning that bees employ. Other methods include the ability to differentiate between two odours (differential learning), and the ability to reverse the association of two odours (reversal learning). Gómez-Moracho and her team infected bumblebees with N. ceranae spores and tested how these three different methods of olfactory learning were affected by the fungus.
What they found was that the fungus had a negative effect on absolute, differential, and reversal learning in the bumble bees, however, long term and short term memory were unaffected. All these things are important for bees to effectively forage, as well as chemically communicate with one another, which can compromise colony foraging success and potentially lead to colony collapse. Thus, infection with N. ceranae can have devastating results on bumble bee populations.
N. ceranae is rapidly spreading around the world, and is becoming an emerging threat to not only bee populations, but to many other populations as well. As mentioned previously, bees are prolific pollinators and many organisms, mainly plants, require pollination as part of their life cycles. A reduction in the efficiency in which bees pollinate may also lead to a reduction in many of these species that require them.While this study was done on bumble bees, other studies have shown that N. ceranae may affect honey bees much more strongly. Infection with this fungus in honey bees may lead to a worldwide shortage of honey, a food item that is considered a staple in many houses, thus impacting the economy. N. ceranae and bees have been around for millennia, yet the fungus is spreading globally, infecting bees at an alarming rate. The only explanation for this rapid spread must be because of human activity. Worldwide trade as a vessel for the transportation of spores, as well as climate change may be responsible for the rapid spread. Thus, it is important that we look at our impact on the environment and really see how our activities are affecting wild populations so that we may be able to develop methods of reversing our impact. Bees are an important thing to buzz about, because if we don't, we may lose them forever.
Comments