The researchers said that they have learned to diffuse the “smell of fear” produced by predators: it naturally repels and destroys harmful insects.
Insects rely on their sense of smell to find food, a mate, and a place to live, which is why the authors of the new work used smells to control their behavior.
Aphids are one of the most destructive pests on many crops. If there are a lot of aphids, then it can transmit pathogenic microorganisms to plants, and this insect also has an increased resistance to insecticides.
Ladybugs feed on aphids, so their smell repels some of the herbivorous insects. Ladybug odor can also slow down aphid breeding rates.
The authors of the new work decided to study this characteristic odor emitted by ladybirds in order to control pests. They started by identifying and extracting the odor profile of live ladybirds using gas chromatography – a mass spectrometry that separates and identifies individual components of ladybird odor.
To see which compounds the aphids would react to, they hooked up the insects to an electroantennogram machine (EAG) and tested them for every single odor that the predator emitted. The researchers then measured the strength of the insects’ reaction and found that methoxypyrazines, such as isopropyl methoxypyrazine, isobutylmethoxypyrazine, and sec-butylmethoxypyrazine, caused the strongest rejection.
Once the compounds were identified, the team proceeded to create a special blend of scent that can be sprayed across a garden or field.
In the next phase of the study, the authors will test their mixture on other pests.