Pollinators are in trouble
The conversion of natural ecosystems, like forests and prairies, to agricultural land has wreaked havoc on many species, from large mammals to birds and small insects. In particular, pollinators have been severely impacted by these land cover changes because the plant species they would normally visit for nectar or pollen have been largely replaced with crops like corn, soy, and wheat. This has contributed to a dramatic decline in the number and types of pollinators present throughout the landscape. To remedy this, scientists and policy makers have worked together to implement expensive initiatives encouraging the planting of wildflower mixes in and around farm fields to help increase pollinator habitat. While the wildflower mixes are undoubtedly helpful for pollinators, some scientists are beginning to wonder if a potential solution has been lurking in farm fields all along.
Weeds get a bad rap, but that’s about to change
Anyone who has spent time gardening or farming knows that fighting weeds is a perennial problem. The weeds compete for resources against whatever species have been intentionally planted, and so are often exterminated by whatever means necessary. It turns out that weeds may not be all bad, though, and could actually be beneficial when it comes to supporting pollinators and other important insects. In a recent study, researchers from the University of Sussex in the United Kingdom compared the number and types of pollinators that visited common weed species to those visiting recommended wildflower mixes in agricultural fields. They found that pollinators visited weeds twice as often as the wildflower mixes, and the weeds supported a greater diversity of pollinator species. Way to go, weeds!
To confirm whether their findings aligned with what other scientists have observed, the study authors also analyzed data from two existing databases containing information on the diversity of pollinators associated with different British plants, including wildflower and weed species. This analysis revealed that weed species were associated with four times more pollinator species than the wildflower species, which supported the authors’ findings from their field study. On top of that, the weeds also supported more at-risk pollinator species, including those that are on conservation priority lists. These findings strongly suggest that we should abandon our weed-averse attitudes and instead learn to welcome them into our gardens and farm fields.
Three of the common weed species included in this study, from left to right: common thistle, field thistle, and ragwort.
What makes weeds so tasty?
Although the researchers did not directly test why the weeds were more attractive to pollinators than the wildflower species, they provided several potential explanations. First, the weed species they studied were generalists, meaning that a wide variety of pollinators can access the flowers and acquire nectar from them. This is in comparison to specialists, which only one or a few species of pollinators can successfully pollinate. Second, the weed species of interest produce more nectar than the wildflower species, making them a more appealing stop for a meal. Lastly, the weeds are widespread geographically, such that pollinators have many opportunities to visit them across many locations.
From a politician’s perspective, using weeds to support pollinators might be especially appealing from an economic standpoint. Compared to implementing expensive wildflower programs or rallying teams to control weeds in public areas, it would be much cheaper to simply leave the weeds in exchange for a boost in pollinator populations. However, from a farmer’s perspective, the story is slightly more complicated. We already know that weeds are good at rapidly colonizing and growing in farm fields, so it would take little money or effort to establish the weed communities for pollinators – the weeds do all the work themselves! Weeds can be problematic for the very same reason, though; when they are too efficient at spreading and growing, they can interfere with crop yields, putting a farmer’s livelihood at risk. On the other hand, when considering the costs associated with controlling weeds in farm fields, it’s possible that any yield losses could be balanced economically by savings from reduced weed control needs. Moving forward, it will be critical to help farmers and gardeners alike assess the costs and benefits of a new pollinator-friendly approach to weed management.