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Bioengineered plants help produce moth pheromones for pest control

Pheromones are often used by farmers to control pests, but the chemical process to produce them is expensive. A method of making them using biotech oil plants could be cheaper

Surroundings


September 1, 2022

The camelina oilseed plant can be used to make insect pheromones

Kurt Miller

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

Pheromones are chemical signals that trigger a behavioral response in members of the same or closely related species. For decades, farmers have been using pheromones to keep pests away from high-value crops like apples and grapes, for example by trapping the chemicals or saturating fields with them to make it difficult for the insects to find mates. But the chemical process for making pheromones is too expensive to use for low-value row crops such as corn, soybeans and cotton.

Hong-Lei Wang at Lund University in Sweden and colleagues bioengineered plants to produce a sex pheromone molecule secreted by two harmful pest species: female diamondback moths (Plutella xylostella) and cotton bollworms (Helicoverpa armigera).

The team used the bacteria 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 — formed the fatty acid chains in the geometry necessary for diamondback moths and cotton bollworms to recognize the scent. After the camelina seeds were harvested, the researchers purified and processed the modified fatty acids in the lab to arrive at the final pheromone.

To compare their plant-derived pheromone to a chemically derived pheromone, the researchers strung male moth traps and saturated plots together. In both cases, the effects were similar, with moths in the trap and populations declining at the same rate.

Thousand hectares of oilseed crop for each pheromone could produce enough for the whole world, says Agenor Mafra-Neto, CEO of ISCA, an American company that commercializes the pheromones. The team conducted a cost analysis and found that pheromones would be cheap enough for crops like soybeans if they could be produced for less than $100 per kilogram. Current methods cost $150 to $400 per kilogram. The researchers estimated that their method would cost between $70 and $125 per kilogram.

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

Reference magazine: Nature Sustainability, DOI: 10.1038/s41893-022-00949-x

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