Pheromones are often used by farmers for controlling pest insects but the chemical process for producing them is expensive. A method for making them using bioengineered oil plants could be cheaper

By James Dinneen

A bioengineered oilseed plant can produce a moth sex pheromone molecule used to control insect pests.

Pheromones are chemical signals that cause a response in members of the same or closely related species. For decades, farmers have used pheromones to keep pest insects away from high-value crops like apples and grapes by luring them into traps laced with pheromones or making it difficult to find a mate by saturating fields with them. But the chemical process for making them is too expensive to use for lower-value row crops like maize, soybeans and cotton.

Hong-Lei Wang at Lund University in Sweden and colleagues bioengineered plants to produce a sex pheromone molecule made by female diamondback moths and cotton bollworms, both damaging pest species.

The team used the bacterium Agrobacterium tumefaciens to introduce two genes into the oilseed plant Camelina sativa. One gene caused the plant to produce more fatty acids. The other – derived from a moth – shaped the fatty acid chains into the geometry needed for diamondback moths and cotton bollworms to recognise the scent. Once the camelina seeds were harvested, the researchers purified and processed the altered fatty acids in the lab to arrive at the final pheromone.

The researchers compared their plant-derived pheromone to a chemical-derived one by both lacing traps for male moths and saturating plots of land with each pheromone. In both cases, the effects were similar, with moths trapped and populations declining at the same rate.

A thousand acres of oilseed crop for each pheromone could produce enough for the entire world, says Agenor Mafra-Neto, CEO of ISCA, a US company commercialising the pheromones. The team performed a cost analysis and found pheromones would be cheap enough for crops like soybeans if they could be produced for less than $100 a kilogram. Current methods cost between $150 to $400 a kilogram. The researchers estimate their method would cost between $70 and $125 a kilogram.

Unlike regular insecticides, pheromones act only on target species and are not toxic. Insects also don’t develop resistance to them. Anamika Sharma at Florida A&M University says cheaper pheromones could help reduce insecticide use, but won’t work for every pest or control pest populations on their own. “We want to combine a lot of strategies – not just chemicals – to make sure we can manage the pest population,” she says.

Journal reference: Nature Sustainability, DOI: 10.1038/s41893-022-00949-x