An article in the in the journal BioMed Central Biology describes a new pesticide-free and environmentally-friendly way to control diamondback moths (Plutella xylostella) with a “self-limiting gene.” The DBM is an invasive species and is a serious pest of cabbages, kale, canola and other crucifer crops around the world.

The self-limiting gene technique, developed by the British company Oxitec, has already been trialed against dengue fever-carrying mosquitoes, successfully reducing their populations by over 90% in Brazil, Panama and the Cayman Islands — an unprecedented level of control by any method, and one that is leading to municipal projects following approval by the national biosafety group in Brazil for releases throughout the country.

The approach was inspired by the Sterile Insect Technique (SIT), which has been used worldwide for more than 50 years, where male insects are sterilized by radiation and released to mate with pest females. Without offspring the population crashes. Oxitec’s approach harnesses the natural reproductive instincts of the male insects, but doesn’t rely on radiation to sterilize them, which can affect many genes and the insect’s ability to mate. Instead, a self-limiting gene is carried by the insects, in this case diamondback moths. The engineered male moths are released to mate with the pest females, and because their female offspring do not survive to reproduce, the number of pest moths dwindles. The Oxitec moths also carry a color marker for monitoring.

In the newly published results, scientists from the US, UK, and China show that diamondback moth populations in greenhouses were well controlled within eight weeks.

Unlike insecticides, which can affect a broad variety of insect life, including bees and other beneficial insects, this approach is entirely species-specific, affecting only the targeted pest population. The self-limiting gene is also non-toxic, so the moths can be eaten by birds or other animals with no adverse effects.

“This research is opening new doors for the future of farming with pest-control methods that are non-toxic and pesticide-free,” said Dr. Neil Morrison, lead DBM research scientist at Oxitec and a co-author on the paper. “We all share an interest in safe and environmentally friendly pest control, so this is a very promising tool that could be put to good use by farmers as part of integrated pest management (IPM) strategies for healthy and sustainable agriculture.”

Co-author Tony Shelton, professor of entomology at Cornell University, is also an expert on IPM, and hopes that the new technology can be used as a part of more agro-ecological farming systems, including organic production.

“Both conventional and organic pesticides are failing to control DBM, so it’s time for scientists and farmers to work together to find new tools,” he said.

The struggle with diamondback moth for cruciferous vegetable production costs farmers around the world up to $5 billion dollars each year. DBM is poorly controlled by current methods, especially as the moths are becoming increasingly resistant to insecticides.

“Diamondback is a serious problem for farmers in New York State and around the world — anywhere cruciferous vegetables and field crops are grown,” Shelton said. “These moths invade and attack the crops, and they are developing resistance to insecticides, so we urgently need new tools to better control them.”

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– Pest control and resistance management through release of insects carrying a male-selecting transgene