Plants could be used as ‘green factories’ to make aphid sex pheromones or as natural dispensers as part of pest control strategies on farms, after scientists in Sweden successfully inserted genes into the chloroplast of two species to produce the attractive molecules.
The team, based at Lund University, found that when they genetically engineered the plants Nicotiana benthamiana and Camelina sativa using the genes, the plants could produce nepetalactone, which can be used as part of sustainable approaches to tackle aphids, which are often controlled using broad-spectrum insecticides.
Insect sex pheromones are widely used as part of integrated pest management strategies, as they can work as attractants to trap insects in large numbers and reduce crop damage, monitor pest numbers to inform judicious pesticide use, as well as interfere with mating to limit populations.
However, such usage is more widely seen targeting crop-feeding moths or flies. Currently, nepetalactone and nepetalactol, a similar pheromone which brings a response in aphids and their natural enemies, are not widely available on the market, and are expensive when produced synthetically.
The new approach offers the opportunity for high yields of the compounds from the plants’ leaves. The team offered three possibilities for how the new system could be applied:
- Using the plants as ‘biofactories’ for man-made baits for use in the field
- Using them as natural dispensers, to interfere with aphid mating behaviour
- Recruiting aphid natural enemies, which have been shown to use sex pheromones to find their prey
“As this is a proof‐of‐concept study, further work is needed to determine which strategy may be most efficient; for instance, by performing insect choice assays with plants capable of producing aphid sex pheromones, testing the behaviours of both aphids and their predators in both laboratory and field conditions,” the scientists wrote in the journal Physiologia Plantarum.
The team also suggested that the repellent potential of the sex pheromones should be tested against asexual phases in aphid life cycles and could also be trialled against other pest insects such as mosquitoes, cockroaches and flies.
