A team of researchers at University College London has found that tropical pollinators are more than 70 percent less abundant in areas with intensive agriculture compared to wild sites. The experts report that more sustainable agricultural practices are needed to prevent widespread losses of bees and other valuable insects.
“Pollinating species are thought to be in decline globally due to combined pressures of habitat loss and climate change. Here, we found that pollinators in tropical regions are the most likely to decline as croplands continue to expand and intensify, and as animals in the tropics are also particularly vulnerable to the impacts of climate change,” said study lead author Joe Millard.
The researchers set out to investigate the impact of various land-use types and intensities on pollinator biodiversity worldwide. The analysis was focused on 12,170 sites and 4,502 pollinating species, including insects, birds, and bats.
The study revealed that low levels of land use intensity appear to have beneficial effects for pollinators, even compared to natural vegetation. By contrast, the diversity of pollinator species suffered as the intensity of different land uses increased.
In the tropics, species richness was reduced by 44 percent and total abundance of all pollinators combined decreased by 49 percent in high-intensity agricultural sites compared to natural vegetation. Furthermore, the overall abundance of tropical pollinators declined by at least 70 percent in high-intensity croplands.
“More than three quarters of globally important food crops are at least partly reliant on animal pollination, including nuts, berries, and fruits grown in tropical areas,” said study senior author Dr. Tim Newbold.
“Croplands are expected to continue expanding rapidly in the tropics, which could pose a serious risk to local pollinators. As a result, we may see reduced yields of the many tropical crops that depend on animal pollination.”
“Agricultural land management needs to take a long-term outlook to avoid harming pollinators. While maintaining wilderness spaces, so that not all land in a region is given over to human uses, is vital, agriculture can also be done more sustainably without reducing crop yields.”
According to Dr. Newbold, this could mean planting different crops close together, using biocontrol agents instead of insecticides to control pests, planting hedgerows, or agroforestry. He added that consumers can also play their part by choosing more sustainably farmed products.
“Our finding that low intensity urban areas, like villages and green spaces, actually had greater pollinator biodiversity than wilderness areas, shows that urban areas can be good habitats for pollinators, with careful management,” explained Millard. “Planting flowers in gardens, without using insecticides, can help out our local pollinators.”
The study is published in the journal Nature Communications.
By Chrissy Sexton, Earth.com Staff Writer