Researchers have mapped the genome of the infamous desert locust. And it turns out to be huge.

At just under nine billion base pairs, the genome is nearly three times larger than that of humans. “It’s one of the largest insect genomes fully mapped to date,” said entomologist Scott Geib.

The desert locust

Geib and colleagues focused on the species Schistocerca gregaria, better known as the desert locust. It is a notorious species, because it is known for regularly forming huge swarms that – while wandering – gnaw everything they come across. This already happened in the time of the pharaohs and it still happens – in Africa, as well as in the Middle East and southwestern Asia. And still the damage is enormous every time; a small swarm can eat as much as 35,000 people in one day and pose a serious food security problem. Not to mention bigger swarms.


At the moment, the swarms – which usually consist of about 150 million locusts per square kilometer – are difficult to combat. All one can do is locate the swarm and then spray it with a broad spectrum of pesticides. It is hoped that the desert locust genome will provide more insight into how the species works and ultimately provide new opportunities to combat the millions of locust swarms. “Mounting locusts aren’t always migratory locusts,” Geib explains from. “Sometimes they’re just grasshoppers. We don’t understand what, on a genetic or biochemical level, causes a locust to swarm. By better understanding the genes and mechanisms underlying this process, we also hope to understand how to control the swarming behavior of this species.”

The research

To map the genome of the desert locust, the researchers needed such a locust, of course. And for that they called on researchers in Kenya. Those researchers then tracked down a swarm of migratory locusts and collected locusts until they got hold of two specimens, which then successfully gave birth to a young locust. And the genome of that grasshopper was then sequenced. In addition, because they knew the father and mother of the grasshopper, the researchers were also able to determine from whom certain variations in the grasshopper’s genome came.

Five months

Prior to the research, Geib expected – in view of the size and complexity of the genome – that it would be quite a task to sift through the desert locust genome. But that wasn’t too bad; barely five months passed between the moment the grasshopper was obtained and the researchers had the complete genome in their hands. “Recent advances in sequencing technologies and genome reconstruction algorithms have made genome mapping work well,” Geib said. “But the analysis of the genome will become a lot more difficult because of its size.”

Because of course, the real work has yet to begin with obtaining the genome; interpreting the genome is an enormous task. But one that might be worth it. Because there are still many questions about the desert locusts – despite being infamous and famous for thousands of years. First of all, of course, about their swarming behaviour, as mentioned above. But there is more, says Geib. “For example, we are interested in the question of why this genome is so gigantic. It is three times larger than that of humans and ten times larger than that of many other insects; that’s a lot of extra baggage to carry around. What is the function of all those non-coding regions of this genome and the repetitive elements?” In addition, the genome can also provide more insight into the structure of swarms. “Who mates with whom? Where are they going? By making use of the naturally occurring variations in the genome, we can answer such questions. It’s a kind (a well-known American site for genealogy research, ed.) for grasshoppers.” And finally, the desert locust genome can also provide more insight into related species that occasionally cause a lot of trouble elsewhere, such as the Mormon cricket; a cricket found in West and North America that can grow up to eight centimeters in size and can be a pest for years to decades while swarming.

The research into the desert locust is not an isolated incident; it is part of a much larger research project that aims to eventually map the genomes of more than 100 pest insects. “Right now, the desert locust genome is the largest genome we’ve come across,” says Geib. But the investigation is still in progress. “In any case, we have started sequencing more than 100 pest insects, including well-known specimens such as the Asian giant hornet, the spotted lanternfly, the Mormon cricket, the cotton weevil, etc. In addition, we are also focusing on lesser-known pests of great importance for agriculture, such as insect pests that threaten stored grain, special and important crops.”