The Locust Plague and Climate Change: Local Professor Weighs In

In June, NPR published an article discussing the enormous swarms of locusts that descended upon the Horn of Africa like a Biblical plague this year. Vast clouds of these destructive insects will travel hundreds of miles, decimating crops and forage fields along the way. 

 According to the article, The Food and Agriculture Organization predicted in June that if the locusts continue to swarm throughout the area, 10% of the world’s population will be threatened with starvation.  

 Paul Jepson, a semi-retired professor at Oregon State University, is a contract worker for the U.S. Agency for International Development and the U.S. Department of Agriculture Foreign Agriculture Service. He has spent time in Africa working with locust and armyworm management, and is currently working with teams helping to manage this year’s swarms.   

Jepson says locusts are biologically advantaged when it comes to swarming and reproducing: “Locusts evolved to exploit seasonal and widely separated explosions of plant growth, and they can detect rainfall and subsequent plant germination from hundreds of miles downwind.”   

This evolutionary leg-up is paired with the fact that agriculture allows plants to be grown in places where typically green food would not be available, sustaining the outbreaks and, Jepson believes, making them worse.   

Grasshoppers vs. Locusts  

Most of the time, locusts exist in a grasshopper phase, they keep to themselves, and are green in color. However, they have a second “life form,” Jepson says, “triggered by food abundance and population density, that can result in highly mobile walking and flying swarms.”   

This second life form is called a Gregarious Phase and is brought on by environmental factors, specifically a large rainfall. The physiology of the locust changes, and instead of repelling each other, they come together. If the moist conditions persist, they start to move together in coordinated masses. This change in response to environmental conditions is called phenotypic plasticity  

One of the biggest factors in the extent of the problem is that climate change has made it difficult to both predict and prevent swarms of this magnitude. Jepson says that while plagues of locusts have taken place throughout history, East Africa hasn’t seen one in nearly 40 years.   

He also said that temperature and water drive insect populations in different ways. For example, warmer temperatures allow insects to complete larger numbers of generations every year, and the survival rate over winter can increase, although warm weather can also aid predators and parasites who prey on the insects.   

“Climate change basically makes everything less predictable, and the past ceases to be an effective guide to what we could expect and how we might respond,” he said.  

Right now, methods for control and management are limited.   

“Aerial spraying of flying or roosting adults can ‘flatten the curve,’” Jepson says, utilizing a phrase we are all too familiar with, in relation to the COVID-19 pandemic, “and ground sprays of hopper bands [the non-flying nymphal stage of locust that moves as a cohesive unit] and crops can limit feeding damage – but numbers can be overwhelming, and populations can cover a large area, arriving unanticipated.”   

Jepson says that one alternative to chemical pesticides is to spray out spores of a fungal disease specific to locusts – harmless to humans. This disease creates an epidemic within locust swarms, and can help to kill off the larger populations. While the production of this compound has been slow, it is effective and efforts are being made to make more of it available.   

Climate Change & Locusts  

“The most effective management operations have been a huge on the ground logistical operation that combines monitoring and reporting, with coordinated responses that protect food crops with pesticide sprays.” Jepson said.   

This current outbreak caught organizations and governments by surprise and was a perfect storm. According to Jepson, weather patterns encouraging population growth, insecurity in some regions preventing monitoring populations, a lack of expertise on the ground because swarms have not been seen for a long time, and lack of access to some of sprays and equipment that is used all partly explain why things have progressed so “shockingly.”  

In Corvallis, we benefit from the wealth of resources in the Willamette Valley and, so far, we haven’t seen Biblical Plagues of Locusts, but that doesn’t mean we can’t help.   

Jepson says the best thing we can do is to recognize that: “Our capacity to manage everything, and anticipate and prevent the worst that can happen is limited. Climate and weather have direct and indirect impacts on livelihoods and wellbeing, and the most vulnerable populations in the world are exposed to the most extreme combinations of these factors.”  

He says in order to help, our focus should be on supporting agriculture and it’s sustaining role with a growing world population, and encourages the Corvallis community to support the established resources like OSU in order to help protect the most at-risk in our world.   

“If you allow institutions and expertise to decay, it is not possible to respond any longer to likely, but sporadic catastrophes. We cannot afford to erode the mechanisms that underpin our resilience,” Jepson said. “It is a false economy, and the lessons are all too apparent to everyone this year. If responses are too slow, inadequate, or uncoordinated, they are ineffective, and the vulnerable cannot escape the outcomes.”  

By Kyra Young