May 10, 2020

Texas A&M Entomologist Provides Insight on Global Locust Devastation

Reporting Texas

Hojun Song. Courtesy Hojun Song

In February, a group of desert locusts descended on East Africa, threatening agriculture and livelihood.  In April and May, a second locust invasion — estimated to be 20 times larger than the first — descended on the region.

Locusts have plagued the earth throughout recorded history. Agriculture in Africa suffers greatly because of locust swarms. According to the U.N. Food and Agriculture Agency, the desert locusts are a “major hunger threat” to the world. A swarm can be 460 square miles in size, completely block the sun and eat 423 million pounds of plants every day, according to National Geographic.

Hojun Song, a professor in the Department of Entomology at Texas A&M, has been researching grasshoppers and crickets, with a focus on the evolution of swarming locusts. Reporting Texas spoke with Song on the video conferencing app Zoom about his research. Herewith excerpts:

What caused the East African outbreak?

Many times when you have this unexpected outbreak, especially recently, it is due to a shift in climates. We believe that the East African outbreak is due to a very unusual series of cyclones that dumped a lot of rain in 2018 and early 2019.

How long will it last?

I wouldn’t be surprised if this lasts three, four, five years or longer.

The longest [locust plague] lasted 10 years. On top of that, there’s the coronavirus, which makes it more difficult for people to gather and work as a team. There are international efforts by the Food and Agriculture organization. They have a team of locusts control officers who are trying to mitigate this situation.

 In dollars, how much devastation do you anticipate?

That’s actually difficult because I’m not familiar with their GDP and things like that. But if the country relies on farming, they basically have a complete loss of crops. Not just crop land, but also there’s a loss for the famine and the environmental damage. So it’s probably hundreds of millions of dollars, if not more.

What does the future of East Africa look like once this outbreak subsides?

I think they will recover. Locusts have affected humanity for thousands and thousands of years. People will suffer and crops will be lost. Luckily, they don’t carry disease. They have to run their course, but because locusts are mobile, I fear that they might actually expand to other parts of Africa. After a few years, I think things will go back to normal, but we always need to be ready to deal with this problem.

Are locusts important to the ecosystem?

Locusts are problematic because we do agriculture, and agriculture itself is not beneficial to the ecosystem. Agriculture is a human solution for human problems. When we do that, we’re creating the buffet table for them. Locusts eat what we want to eat. They have a definite role because they feed on plants and provide nitrogen. So, they’re really important for nutrient cycling.

Pesticides are an effective way to control locusts, but pesticides harm honeybees. Are there any environmentally friendly ways to control locusts?

The answer is actually quite complex. Let’s say you have a cloud of locusts descending upon a town, you’re too late. You can spray [pesticides], but it will also be very harmful to other organisms in the environment. The last thing they want to do is to spray, but that’s probably the only way to do it. Actually, it’s not very effective. Think about it, a large swarm can contain billions of locusts, right? You are out there with the airplane spraying [pesticides]. How many can you actually kill? Not many. Even if you kill millions, there are billions out there.

At that point, you’re reactive to the problem and not really solving it. So what you want to do is to track the locust before they become problematic, which is hard to do.

There are some options that use biological control options like fungal pathogens. Fungus can kill locusts. There are a couple of different species of fungus that people use as a bio pesticide. While effective, it takes more anywhere between seven to 14 days to be effective. So it’s also not very good. Once you have a large-scale outbreak, there’s really no good way of controlling them.

There are grasshoppers in North America but no locusts. Why?

All locusts are grasshoppers, but not all grasshoppers are locusts. Many of the locust that are problematic are associated with either desert or the tropics. In North America, we have a temperate climate and are super urbanized.

There used to be a species called the Rocky Mountain locust. It was probably the worst swarm in the history of the locust. Due to habitat change, urbanization and changes in farming practices, the areas that the grasshoppers and locusts preferred basically disappeared. 

Should we start taking precautions?

I think we should learn about the species more and should have a mitigation plan, but as you see with the coronavirus, the government’s responses are not always fast. Many times it’s very reactive, unless it has a significant economic damage. I fear there is possibly a species found in Mexico that will affect Texas. I predict in 10 to 15 years, we might have locusts because of climate change.

There’s a locust species 50 miles south of Brownsville, Texas. 50 miles is nothing for the locusts. They travel about100 miles a day or so. They also feed on cotton, which is the real problem in Texas.

What’s next in your research?

My lab focuses on the Central American locusts, but there are several other species of locusts that we do not know much about. So the future is to not only learn more deeply about the species that I work on, but also work on other locusts species to figure out if there’s any common things that we can learn, so that we can apply similar techniques to control them. We just don’t have that answer yet.