Genome of destructive desert locust 3 times larger than humans

By Danny Halpin via SWNS

The genome of the destructive desert locust is three times larger than that of a human, scientists have revealed.

It is hoped the sequencing of the huge genome will lead to a deeper understanding of the insects and more effective ways of controlling their rampages.

US scientists have for the first time sequenced and built the genome of the most destructive migratory insect in the world which has plagued farmers since the time of the Pharaohs.

The plagues are cyclic and have been recorded as far back as ancient Egypt in 3200 BC.

More recently, there have been swarms in 1967-69, 1986-89 and 2020-22. They cause devastation in East Africa, the Middle East and southwest Asia, threatening the food supply to many countries.

The damage can be huge. A small swarm can eat as much food in a day as would feed 35,000 people.

Biblical-size swarms the size of New York City can eat in one day enough food for 30 million people, according to the Food and Agriculture Organization of the United Nations.

At present, swarms are mostly controlled by finding and spraying them with pesticides.

The scientists hope their genomic work will reduce dependence on fighting the bugs with chemical warfare.

Dr. Scott Geib, an entomologist from the Agricultural Research Service (ARS) in Hawaii, said: “Having a high-quality genome is a big step toward finding targeted controls.

“It will also give us valuable information about relatives of the desert locust that are major pests in the Americas such as the Mormon cricket, another swarming species that can impact US food security.”

Working with scientists from the US Department of Agriculture (USDA), Dr. Geib and his team were able to map the genetic make-up of the desert locust, an enormous job as it is three times larger than the human genome and has just under nine billion base pairs which are the basic building blocks of the DNA structure.

The desert locust’s chromosomes are larger than the entire genetic structure of the fruit fly, the first insect to have its genome built by scientists.

Dr. Geib said: “With the desert locust, we were dealing with a much larger genome in many fewer pieces – about 8.8 Gb in just 12 chromosomes.

“Next to the fruit fly, it’s like an 18-wheeler next to a compact car. It was like sequencing a typical insect genome many, many times over.

“But with today’s advances in DNA sequencing technologies, we are now able to generate extremely accurate genomes of insects that previously would have been unapproachable.”

He added: “We were concerned that, faced with this huge and very likely complex desert locust genome, it was going to be an extremely long and difficult job.

“However, we were able to go from sample collection to a final assembled genome in under five months.

“The desert locust is one of the largest insect genomes ever completed and it was all done from a single locust.”

That one locust came from chemical ecologist Baldwyn Torto with the International Centre of Insect Physiology and Ecology in Nairobi, Kenya.

He and his team tracked down swarms of locusts and collected samples across Kenya until he had two parents from which he was able to breed a pedigree offspring.

ARS has made the genome available to the international research community through the National Center for Biotechnology Information.

This work is part of the Ag100Pest Initiative, an ARS program to develop high-quality genomes for the top 100 arthropod pests in agriculture as a foundation for basic and applied research.

USDA Foreign Agricultural Service coordinated this research opportunity and provided funding from the US Agency for International Development Africa Bureau through an interagency agreement.