(CN) – Researchers at Cornell University hope to tackle a small pest and a big problem that has plagued agriculture since the 1800s: controlling the destructive diamondback moth through genetic engineering.
The diamondback moth is a small creature, about the length of two grains of rice, but they are capable of inflicting billions of dollars of damage on cabbage and broccoli crops every year. In fact, the moth is Enemy No. 1 when it comes to the cabbage and broccoli family. Cornell University's agriculture research division in Geneva, New York, is studying how to invade the invaders with genetically engineered male diamondback moths that mate with females, which then die before reaching adulthood.
The federal Animal and Plant Health Inspection Service said last week it is seeking public comment on Cornell's plan to release sterile male diamondback moths from the United Kingdom on Cornell’s research grounds.
The diamondback moth (Plutella xylostella) is the world’s worst insect pest of brassica crops (cabbages, canola, broccoli, cauliflower and kale). The pest costs farmers $4 to $5 billion annually worldwide, according to the U.S. Department of Agriculture. The pest arrived on ships in the 1800s, according to Tony Shelton, head of the Shelton Lab at Cornell University’s agriculture research station.
Female diamondback moths can lay over 150 eggs during their short lifetime, and a generation can be produced in as little as two weeks. This invasive pest probably originated in Europe, but is now found throughout the world, including New York and other states that farm brassica vegetables.
Shelton is the leader of the diamondback moth project at Cornell University. The Shelton Lab is part of Cornell University’s Department of Entomology and is about 50 miles from the main campus at the New York State Agricultural Experiment Station in Geneva, New York, in the heart of the Finger Lakes.
Shelton works with crucifer farmers globally, and this week he was off on a plane to Bangladesh. “Wherever crucifers are grown, diamondback moths are there,” he said in an interview.
Biological controls are part of the solution to controlling the tiny invaders, Shelton said. Best methods of controlling the pests are a combination of biological controls, plowing fields after harvest, and “judicious use of insecticides,” Shelton said. “Genetic control using a self-limiting method could make a valuable contribution of integrated pest management.”
Diamondback moths infest crucifer crops in all U.S. states, but most severe damage occurs in warmer areas where more generations of the moth are produced, Shelton said.
The proposed release of diamondback moths would be at the Cornell research station and would not exceed two years, according to the application. The release would be limited to an experimental field, up to 10 acres. The release site is surrounded by other agricultural fields within the research station's 870 acres where diamondback moths occur naturally. Shelton's team would release up to 10,000 male genetically engineered moths per release, up to 30,000 males per week.
The moths that Cornell University is looking to release onto its research grounds are genetically engineered to be sterile, and they also have a fluorescent red marker that shows up under special light. The field studies at Cornell are funded by the U.S. Department of Agriculture and Oxitec, the company that designs and breeds the diamondback moths to be released.
This biological approach to controlling pests has been used for about 50 years and is known as the sterile insect technique. In this technique, male insects are sterilized with radiation and then released to mate with female pest insects of the same species. Because the males have been sterilized, there are no offspring from the mating and this reduces the pest population over time with multiple releases, according to the USDA.
There is one problem with this technique in diamondback moths, though. The radiation used to sterilize the males can affect many other genes and the sterilization reduces the fitness of the male insects to the point they are actually less able to mate with the females.
Affiliated with Oxford University, Oxitec scientists developed a way to produce the same sterility effect using genetic control instead of radiation. By adding two self-limiting genes into the species, the moth offspring are unable to survive into adulthood. Scientists also added a color marker into the genetically engineered moths to be able to track and trace the insects in the environment and to distinguish Oxitec insects from the local pests.
Until now, farmers have sprayed crops to reduce infestation from diamondback larvae, but the moths have developed resistance to the poison, according to the USDA.
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