Flight of the sniffer bees

Honeybees continue to cause quite a buzz with their smarts. Previous studies have found that not only can they understand basic maths, they can also connect symbols to numbers and transfer information about an object from one sense to another.

Now, new research published in the journal Current Biology, has found that honeybees can be scent-trained to favour specific crops, leading to a significant increase in sunflower crop production.

In a process similar to letting a dog sniff an item to pick up a scent, researchers from Universidad de Buenos Aires, Argentina, fed honeybees food scented with odours that mimicked sunflowers.

They then monitored their foraging behaviours, finding the training led them to visit sunflowers more. The honeybees also brought more sunflower pollen back to the hive.

“We show that it’s possible to condition honeybees to a rewarded odour inside the colony, and this experience modifies the bees’ odour-guided behaviour later,” says lead author Walter Farina. “The most surprising and relevant result is that foraging preferences for the target crop were so prolonged and intensive that it promoted significant increases in the crop yields.”

Farina and colleagues developed a synthetic odour mixture that the bees associated with the natural floral scent of sunflowers that they then fed to the hive. They found that the odour influenced the foraging preferences of honeybees, indicated by their waggle dance – a signal that recruits nestmates to the location of a profitable foraging site.

And profitable it was; their frequent visits increased sunflower crop yields from 20 to 57%.

A key factor in the training was that the odour was not exclusively learned at the foraging site, but also inside the nest.

“This occurs, for instance, when scented food from successful foragers is unloaded and distributed amongst nestmates,” the authors write. “Such social learning is key for adaptive collective responses, as it enables workers to acquire information about different foraging options directly inside the nest.”

Farina and colleagues say that growing global demand for pollination services is leading producers to consider new strategies in pollinator management, one of which could be scent training.

“Through this procedure, it is possible to bias honeybee foraging activity and increase yields significantly,” Farina says. “In other words, pollination services might be improved by pollinator-dependent crops by using simple mimic odours as part of a precision pollination strategy.”

The researchers also highlight that scent training has numerous benefits over traditional pollinator-management strategies.

Methods such as spraying Nasonov pheromone on flowers to attract bees lead to a lack of flexibility that is crucial for colonies to switch among food sources to meet their nutritional requirements.

“Based on bees’ ability to respond to learned cues, foraging preferences for the sunflower can revert if cues are no longer associated with reward,” they write.

With scented food, there is also less chance of compromising the environment and other pollinators.

The researchers are now looking at how other odour mimics could be used to improve the pollination efficiency and productivity of other pollinator-dependent crops such as almonds and pears.