In 10 seconds? Intensive agriculture farmlands most impacted by climate change have seen a major decline in insects – a new study has found. This matters because insects are not just a nuisance but pollinators and important parts of the food chain.
How does climate change impact insect populations? Despite there being an 11% increase in freshwater insect abundance over the decade, (abundance being the number of individuals per species) at present, about one-third of all insect species are under threat of extinction, with 41% predicted to go extinct in the next few decades.
Why should I care about the loss of insects? As well as playing a role in removing waste and controlling pests, insects are a major part of the food chain and without them, many ecosystems would collapse. However, with 35% of all food crops depending on pollinators for production, this job, performed by insects is arguably the most important to us, humans. With the continued decline in insect populations, we could see a reduction in yield of over 90% in some foods, such as some fruits and cocoa beans, and although overall production loss has been predicted to be relatively low (5% and 8% in high and low-to-middle-income countries, respectively), we are becoming more reliant on pollinator-dependent crops. This means there will not only be greater decreased yield rates but also a loss of income to the countries most affected.
Where is this likely to have the biggest impact? In warmer climates. Out of the estimated 5.5 million species of insects, 85% live in tropical regions. This can be a problem because, unlike humans, insects rely on their environment to regulate their body temperature (thermoregulation), which means they rely more on micro-habitats such as shady conditions to survive warmer temperatures. Additionally, insects in the tropics already have a narrow thermal tolerance and are living close to their thermal optimum, so are more sensitive to the increasing temperatures resulting from climate change.
Okay, but what has farming got to do with the decline in insects? Studies have found that the average number of insect species in decline worldwide is 41%, with the US documenting 51%. It is reported that nearly 50% of this decline is associated with habitat changes. With agricultural crops accounting for 12% of land use, these habitat changes can be linked directly to intensive and monoculture farming (23.9%) and the indirect impacts, including pesticides and fertilizers (22.6%), deforestation (8.8%), and waterway alterations (6.3%).
How is this impact of farming linked to climate change? Previously, climate change has only been attributed to 6.9% of insect biodiversity loss. However, the new study suggests a closer link between intensive farming and climate change. Areas of intensive agricultural land in regions with greater warming see a reduction of insect abundance by 50% and species numbers by 27%, in comparison to less-disturbed habitats with lower rates of warming (30% and 23% reductions, respectively). There is a higher rate of removal of the habitats needed for survival for intensive agriculture in tropical regions, meaning an amplified effect on insect biodiversity in the tropics. In low-intensity agriculture, with 75% natural habitat cover, insect abundance and species number are only reduced by 7% and 5%, in comparison to 63% and 61% when only 25% of natural habitat is present. This shows that retaining natural habitats is vital for buffering against the impact of climate change on insects.
Is there anything that can be done to prevent the collapse of insect populations? Importantly, we need to mitigate climate change by limiting anthropogenic warming to 1.5°C, as set out by the Paris Agreement. Other than this, we can reduce the impact of climate change on insect populations and decrease the risk of extinctionby combining the reduction of high-intensity farming with the implementation of land-management strategies to increase natural habitats.
It's great we care about insects but why pick on farming when us humans need to eat too? OK, it is evident that, with our diet being dependent on pollinated crops, crop yields relating to our food security also need to be considered. This means that we need to find a way to maximize yields in the future but without further deforestation and the destruction of natural habitats through the use of harmful pesticides and fertilizers.
Pollinators - it’s not all about the bees!
When we think of pollinators, we often think of bees. Primarily, we worry about bumblebees when we think of insect declines, and rightly so, as 26% of all bumblebees in the US are threatened by extinction.
However, pollinators also include moths, butterflies, wasps, flies, beetles, ants, birds, and even bats!
Although bees are more efficient pollinators, non-bee pollinators provide up to 50% of all visits to flowers,making up for their slightly lower efficiency.
In fact, some mango, oilseed rape, cherry, carrot, and apple rely heavily on non-bee pollinators. It is also suggested that non-bee pollinators have a less negative response to land-use changes (such as for agriculture) than bees, which have increased diversity in areas with more natural habitats.
Chloe has curated 13 research papers, saving you 45.5 hours of reading time.
The Science Integrity Check of this 3-min Science Digest was performed by Dr. ASM Mainul Hasan.