Climate change is bad news for agriculture; it’s predicted to result in crop loss as unpredictable temperatures and precipitation become more common. This is especially true in areas where food insecurity is already a threat, such as sub-Saharan Africa and parts of Asia.
Insect pest damage is also expected to worsen as climate change progresses (A new PAN publication, Climate Change and Pests, explores these connections in detail!). Understanding how agricultural pests will be affected by climate change, and how farmers can adapt to these changes is important for the future of food production. It’s also critical that farmers are supported in using pest management techniques that are ecologically sound and safe for farmers, workers, and their communities.
Though I encourage you to read the new PAN publication Climate Change and Pests for a detailed analysis and resources on the impacts of climate change on agricultural pests — below are three critical findings:
Climate change will change insect distribution and behavior
Changes in temperature and precipitation will change the feeding habits, movement, and reproduction of insect pests. Higher levels of atmospheric carbon dioxide, or CO2, may make some crops less nutritious, leading to higher insect feeding rates to compensate, causing greater amounts of crop damage.
Warmer temperatures and shorter winters will also make it easier for insect pests to spread into new regions and to remain active for longer periods of time. Extended periods of warm temperatures could also allow some insects to reproduce more quickly and more often, leading to larger populations feeding on crops.
Farmers will need to adapt to these changes in distribution, behavior, and reproduction that may increase and worsen pest damage.
Natural enemies of agricultural pests will be critically important pest management tools
Predators and parasitoids (a type of parasite) control crop damage by eating or parasitizing agricultural pests. Together, these insects that help control pests are known as natural enemies, and contribute to biological pest control, a form of naturally occurring pest management that does not involve the use of pesticides.
The life cycles of many natural enemies are synchronized to those of their insect prey or hosts. This means that shifts caused by climate change in insect pest life cycles will also affect their natural enemies. Natural enemies that can shift their own feeding and reproductive habits in response to changes in their prey and hosts are more likely to be successful pest control agents. Maintaining the diversity of natural enemies will also provide multiple potential sources of pest control instead of relying on chemical pesticides.
Farm Diversification Improves Biological Control
As natural enemies have to adapt to shifting conditions and prey and host availability, there are certain management practices that can help support their survival. Adding plant diversity to the farm landscape and surrounding habitat helps provide food and shelter resources for natural enemies. This includes places to take cover from harsh weather conditions, and floral nectar that adult parasitoids need.
Examples of systems that have been designed to improve biological pest control are the push-pull system in sub-Saharan Africa and alyssum intercropping on the Central Coast of California. Both of these systems include planting non-crop plants, such as Napier grass and alyssum, that are not grown for human consumption, but repel pests or attract natural enemies.
More research is needed to better understand how climate change will affect insect pests and their natural enemies, especially because many impacts will be region-specific. Regardless, evidence suggests that on-farm diversification supports natural enemy populations, which are essential for controlling insect pest damage without the use of highly hazardous pesticides.
In addition to increasing natural enemy abundance, farm diversification and other agroecological practices can help improve overall soil and ecosystem health. Healthier soils support the growth of stronger plants that are more resistant to insect damage and disease. Overall ecosystem health also helps maintain the balance of naturally occuring pest control interactions, reducing the need for chemical pest management.
To support farmers under rapidly changing climate conditions and pest threats, policies designed to incentivize and support agroecology and improving habitat management practices are needed. Such policies can have numerous benefits, including improved natural pest control, healthier soils, and restoration of ecosystem and community health. Together, these reduce the need for pesticides and can even mitigate climate change by reducing input requirements, pollution, and increasing carbon storage in soil.