Create a list of articles to read later. You will be able to access your list from any article in Discover.
You don't have any saved articles.
Loss of tropical pollinators puts chocolate and coffee production at risk
Tropical crops that millions rely on could be at risk of losing their pollinators.
Climate change and habitat loss will limit the reproduction of plants like cacao and coffee, posing a risk to food security all around the world.
Chocolate may face an uncertain future amid rising temperatures and habitat loss.
The cacao tree is notoriously difficult to grow, producing short-lived flowers that are almost exclusively pollinated by a certain type of midge. But the shaded, damp environments that the midge prefers are becoming less common as cocoa production and climate change intensify.
But it’s not just chocolate that’s at risk. New research into the effects of climate and land use change reveals that the growth of mangoes, watermelons and coffee could also be at risk as their pollinators decline.
Dr Joe Millard, a scientist at the Natural History Museum who led the new research, says, ‘Cocoa is experiencing a perfect storm of threats that mean it is at high risk of pollinator losses.’
‘As well as its specialised dependence on Forcipomyia midges for pollination, it is also highly dependent on animal pollination and is almost exclusively grown in areas that will experience novel temperatures by 2050, like the Ivory Coast and Ghana.’
‘While there are steps that can be taken to mitigate these impacts, urgent action is needed to reduce the risks to human health and wellbeing.’
The findings of the study were published in the journal Science Advances.
Pollinators covered in hairs, like this hoverfly, are less able to tolerate rising temperatures. Image © Gerrit Lammers/Shutterstock.
How do climate change and land use change interact?
Both climate change and land use change are known to have a range of different impacts on insects.
Rising temperatures, for instance, are known to affect the size of butterflies, with some species getting bigger while others shrink. This affects their ability to fly and reach the plants they feed on, while unusually hot days can also kill individuals directly.
Changes in how land is used, such as conversion to agriculture, also destroys the habitats which insects rely on as sources of nectar. A 2022 study suggested that land use change has played a large part in the decline of flying insects in the UK, which have fallen by 60% in two decades.
In combination, the effects of land use change and climate change can be even deadlier. One reason for this is due to changes in the microclimate, or the temperature and weather conditions of small areas within a wider landscape.
Pollinators are particularly at risk of these combined threats, not just because of their dependence on certain flowers, but also because they tend to share a set of key characteristics that allow them to pollinate plants.
For instance, many bees and hoverflies are covered in fine hairs that trap pollen, but the same hairs also trap heat meaning the insects respond poorly to higher temperatures.
Because of this, the study predicted that at extreme temperatures the number of pollinators could be up to 61% lower in croplands when compared to natural habitats before climate change.
Given animal-pollinated plants are responsible for a significant amount of global food production, any drop in their pollination rates could have severe consequences for the planet.
The study predicted that watermelons, especially those grown in southeast Asia, will be particularly affected by pollinator losses. Image © ABCDstock/Shutterstock.
Where are crops at the greatest risk, and what will be affected?
To look at which regions of the world might be most affected by changing numbers of pollinators, the team made use of the PREDICTS database. This is a global dataset put together by Natural History Museum researchers that is used to understand how biodiversity is changing in response to land use change.
By combining this data with information on climate change and pollination across the world, the team could predict how crop production might be affected in the years to come.
Their results suggest that the tropics, which are already likely to have been affected by pollinator loss, will probably start experiencing more significant changes.
‘Area of southeast Asia, northern South America and sub-Saharan Africa are most at risk,’ Joe explains. ‘These parts of the world are, and will continue to, experience the greatest increase in temperatures outside their normal range, and are also the areas most dependent on animal pollinated crops relative to their size.’
By 2050, crop production in some of the world’s most populous countries, including China, India, and Brazil, will be at the greatest risk of pollinator losses. This will likely significantly affect crops such as cocoa and coffee, and as these plants are common in small, family-run farms across the tropics the loss of income could push many into poverty.
Nations in other parts of the world tend to rely more heavily on wind-pollinated crops, and so are less reliant on pollinators. While the risks are concerning, there are steps that can be taken to mitigate against them.
One way is to allow patches of natural habitat to grow amongst cropland, which can provide a refuge for pollinating insects and help to maintain a more suitable microclimate.
‘There are also other solutions that can help,’ Joe says. ‘It may be possible to breed varieties of these plants that can reproduce without pollinators, as has already been seen in some crops.’
‘Other technological solutions, like pollination by hand or through artificial means, are already used on a large scale for some crops like vanilla. To buffer against pollinator declines, it might become more common in crops like cocoa, but this will increase the production cost.’
Ultimately, the main way to reduce these risks is to tackle them at the source. Significantly reducing greenhouse gas emissions by 2030 will help to limit the worst effects of climate change, while preserving and restoring habitats will help pollinators to recover.
