Climate Change, Insects and Crop Losses
Climate Change Environment Crop damage

Climate Change, Insects and Crop Losses

Prof Dr Ilan Kelman
Prof Dr Ilan Kelman

In 10 seconds? In a recent Digest, we covered how climate change in tandem with intensive agriculture decimates insects – which in turn cuts agricultural yields. Another recent study looks at the other side of the coin: how to model insect damage to crops – also linked to global warming.

So, what’s new in this study? The paper, in seeking to overcome earlier concerns about our knowledge limits on this topic, proposes a new model. It’s based on environmental variables of multiple characteristics of weather, soil, crop types, and land/crop management. These variables feed into the growth and development traits of both insects and crops which then influence each other. For insects, the life cycle of eggs, larvae, pupae, and adults is covered. For crops, attainable and actual yields are included for different plant parts. Damage to and economic losses from crops could then be calculated, although these tasks are not completed since they were not within the paper’s scope.

What’s the cost of insect damage and what are the benefits of the model? We know it only to some extent. Most quantitative financial analyses are out-of-date and cannot address climate change impacts directly. Why? Because much depends on management decisions and not just environmental variables. Here is an example: one 2017 paper summarises older studies for estimating the costs of invasive insects in spreading diseases under climate change. For the UK, the bluetongue virus might cost £70-200 million ($84-242 million) over the next three decades. Keeping out the Colorado potato beetle through pesticide use could save around £135,000 ($163,000) per year. The numbers are uncertain and depend on numerous conditions. The values are also small, even when multiplied across multiple diseases and countries, compared to the current insect-related crop losses which approach half a trillion dollars per year globally.

The interaction between climate change and crop damage caused by insects. Source: Tonnang, Sokame, Abdel-Rahman et al, 2022
The interaction between climate change and crop damage caused by insects. Source: Tonnang, Sokame, Abdel-Rahman et al, 2022

And what about non-monetary costs? These are also examined because financial losses and gains depend on prices when selling crops. With conflicts, such as Russia invading Ukraine in February, many food prices have increased irrespective of climate change. One analysis avoids pricing complications by looking at percentage changes in crops rather than costs. The scientists conclude that a 2°C rise in mean global surface temperature produces median insect-related losses in wheat (46%), rice (19%), and maize (31%) yields. These numbers assume most other world circumstances remain unchanged which, of course, never happens.

What are other trade-offs? As the new study indicates, agriculture influences insects even as insects influence agriculture. Both agricultural practices and climate change are decimating insects, those that are helpful and harmful to crops, with insect abundance perhaps halving and species numbers down by over a quarter. Meanwhile, many places will become wetter due to human-caused climate change, especially through more intense rainfall, meaning that insects’ eggs and larvae can be washed out, decreasing insect damage potential while harming crops through inundation. As the sea level rises, saltwater infiltrates coastal areas increasing saline content. Some insects adapt while others are being inhibitedby these changing circumstances.

Localized food can help!

All the science discussed here involves mainly large-scale cropping and aggregated models at a global or near-global level. As shown for example in Oslo, Norway, and Bordeaux, France, local centers can produce food according to local conditions including under climate change.

These initiatives help environmental education, provide urban green spaces to support mental and physical health, encourage local identity through involving and linking diverse residents and become a locale for other community activities.

But how much local food could serve local needs? We still need to figure this out. Crop-insect interactions are about much more than food—especially doing better than remote food incurring intensive energy costs for placing it neatly packaged on our supermarket shelves.

Ilan has curated 12 research pieces saving you 42 hours of reading time.

The Science Integrity Check of this 3-min Science Digest was performed by Dr. ASM Mainul Hasan.

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