To fill their houses with blueberries, sunflowers and almonds, farmers rent out honeybees. If all goes well, the bees will pollinate the flowers, resulting in abundant yields. But sometimes the hired bees hum and pollinate wildflowers instead.
The problem is a matter of timing. In order for a beehive to pollinate the plants well, it has to settle down in its surroundings and be happy. That said, it should be placed on a farm before the crop blooms. However, if the crop blooms later than farmers expect, hired bees can develop a preference for nectar from wildflowers near the fields – and ignore the harvest.
Walter M. Farina, a biologist at the University of Buenos Aires, and his colleagues have found a solution to this odor problem, which they reported on Thursday in the journal Current Biology.
Dr. Farina knew from previous work that beehives remember the smells of food collected in the past. Most of all, he knew that these memories could affect the bees’ food.
“This led us to wonder if we could lead bees to certain cultures by introducing a smell of that culture into a beehive and giving them a memory of food they never had,” said Dr. Farina.
Over the course of six years, Dr. Farina and his colleagues smelled sugar water in beehives that had been set up next to Argentine sunflower farms. In some cases, the beehives were given sunflower-scented water. As a control, some beehives received jasmine mixed with water. To keep track of which bees were exposed to the different solutions, the researchers placed colored powders at the entrance to the hives so that bees exposed to the sunflower scent were colored blue and those exposed to jasmine were pink.
To monitor the insect’s reaction, the team installed transparent walls in beehives and recorded the bees dancing. Bees, known as the wobble dance, dance to tell their roommates where they found food. The researchers examined these dances to determine where the bees were looking for food.
To further study how the bees reacted, Dr. Farina and colleagues have pollen traps in the beehives where pollen grains were collected from bees returning from foraging activities that were later brought to the laboratory for identification. The researchers also went to the sunflower fields, caught bees and noted whether they were pink or blue.
The results could not have been clearer as various measurements suggested that the sunflower scent had increased pollination on the plants. When the farmers reported their yields, this was confirmed: fields next to beehives produced between 37 and 61 percent more sunflower seeds with the sunflower solution than fields next to jasmine beehives.
The work has been praised by other entomologists.
“This is real work done in real fields, not just in the lab,” said Martin Giurfa, who studies bees at CNRS Toulouse in France. “These are incredibly encouraging results.”
The study can be good news for more than just farmers.
Wild pollinators Like bumblebees, carpenter bees and mason bees often have problems when exposed to competition from rental bees.
“Our scent technology could help better focus the rent bees on crops and reduce pressure on native pollinators,” said Dr. Farina. Dr. Giurfa agreed that this is possible but added, “We need field studies on these other pollinators to know for sure.”