The European honey bee, Apis mellifera. Image: Aurore Antoine/Flickr
Bees are more integral to a successful harvest than fertilizer, according to a new PloS ONE study. Researchers, led by Alexandra-Maria Klein of the Albert-Ludwigs-Universität, discovered that disrupting insect pollination affected almond tree yields far more than restricting nutrients and water.
Klein, along with her colleagues at the University of California, exposed three sample groups of almond trees to different levels of pollination. One group was pollinated by insects without intervention, while the blossoms of a second group were caged, preventing insects from reaching them. The third group was pollinated by hand.
In addition to the pollination variables, Klein's team treated one group of trees to a standard helping of water and fertilizer, and compared its yields to a group that was given no fertilizer and very little water. Each experiment was conducted in isolation, but the team also studied the manipulated variables in combination to better observe their effects on almond yields and nutritional quality.
The results were dramatic. The trees with caged blossoms barely produced any fruit, but the nuts that did bloom were abnormally large. The hand-pollinated group produced the most nuts, but they were all markedly undersized. The insect-pollinated trees were right in the Goldilocks zone, agriculturally speaking, and they outperformed the other groups by a factor of about 200 percent.
The team also discovered that trees deprived of fertilizer and water were able to make up for the loss over the short-term by subbing in stored nutrients. But no such flexibility was shown for the lack of insect pollinators, making bees and their blossom-loving cohorts a more valuable factor in the success of a crop yield.
A Californian almond orchard. Image via Nehrams2020.
Claire Brittain, one of the authors of the study, explained why insect pollination is so much more effective than other pollination techniques. “Most almond varieties are self incompatible,” she told me in an email. “For this reason, farmers plant two or three varieties in a single orchard. Insect pollination produces better yields because their movement between trees in the orchards helps to transfer pollen from other varieties to the almond flowers.”
The finding further confirms that colony collapse disorder will have disastrous effects on agricultural yields. “Almond needs insect pollinators to be able to produce a commercial crop,” said Brittain. “If there is less availability of honey bees in the future farmers will be forced to pay more for renting honey bee hives. This may in turn increase the price for consumers.”
Given that climate change is also throwing bees off their pollination game, this issue is sure to become more pronounced in the coming decades. For now, Brittain and her colleagues are busy brainstorming novel ways to encourage pollinators to lend their talents to flowering crops.
“One step we are exploring is how to bolster insect pollinators around almond orchards by providing them with floral resources before and after almond bloom,” she said. “This is being done as part of the ICP project which is working on habitat enhancements for crop pollinators across multiple crops in the US.”
Bees and other insects may be small in stature, but their impact on our food supply is clearly enormous. Addressing the multiple problems raised by their declining numbers is paramount, because humans are nowhere near as accommodating about restricted nutritional intake as almond trees.
Correction: The lead photo in an earlier version of this post did not feature the correct species of bee. We regret the error.