How Will Climate Change Affect Insects?

Climate change is perhaps the single most pressing issue affecting human beings. According to the IPCC, we will likely face up to 2 degrees-C of warming over the next few decades. Climate change is expected to cause radical changes in agricultural production and weather patterns across the world.

Changing weather patterns and climate change stressors will also have a massive effect on insect populations. Insects are the most genetically diverse multicellular organisms on the planet, so it is important to understand how climate change will affect insects and their behavior.

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Population Changes

First of all, climate change is expected to drastically change insect populations. As climate and temperatures change, insect populations may increase or decrease. For example, increased rainfall and heat across Africa in recent years have caused populations of armyworms to explode. The growth of this invasive species was also matched by increasing locust populations in the east.

In addition to population increases/decreases, temperature changes can change insect behavioral cycles. Rising temperatures can cause insects to emerge months earlier. Earlier activity cycles run the risk of putting the activity of prey species out of sync with predator species, which could have far-reaching effects on ecosystems.

Increased Feeding

Rising carbon dioxide levels will also change insect activity by altering plants’ nutritional value. Elevated carbon dioxide in the atmosphere reduces protein concentrations in plant matter, which will cause insects to eat more to compensate. Additionally, hotter temperatures will increase insect metabolic activity, causing them to feed more.

According to the UN, approximately 4 billion people worldwide rely on rice, wheat, and corn as staple foodstuffs, and approximately 800 million people suffer from food insecurity. Increased insect feeding can have a drastic negative effect on agriculture and may contribute to food insecurity.

Droughts & Flooding

Climate change is expected to change global precipitation patterns, increasing the incidence of floods and droughts. Since flooding and drought affect plant quantity and nutritional value, they can also change insect populations and activity. Areas with increased drought may see a drop in insect populations, including beneficial insects that pollinate crops and eat other herbivorous pests. Increased flooding may increase vegetation, causing overfeeding and increasing insect populations.

Climate Change is Complex

Credit: Felton Davis via Flickr CC-BY 2.0

Climate change is not the only thing that affects insect populations, and even climate change is not a single variable but several axes of change that include temperature, precipitation, wind patterns, cloud cover, carbon production, and more. As such, the effect of climate change on insect populations and activity may vary heavily from one ecosystem to another. The way that these stressors interact is also not well understood. For example, it is possible that increased temperatures may increase insect feeding behavior but also throw their reproductive cycles out of sync. Extremely high temperatures may also cause insect extinctions. 

One thing is for sure. Climate change is the single most important issue facing life on Earth. Insect monitoring in addition to measures to control carbon and greenhouse gas emissions are necessary to combat the negative effects of climate change.