I just stumbled across this nice video by Rothamsted Research. It’s used on their website to illustrate the research on genetically modified wheat by John Pickett et al. and shows how aphids react to injection of an alarm pheromone into the leaf they are sitting on.
(E)-β-farnesene is an odour, or alarm pheromone, which aphids produce to alert one another to danger. This odour is also produced by some plants as a natural defence mechanism and not only repels aphids but also attracts the natural enemies of aphids, e.g. ladybirds.
Aphids are tiny insects. They cause damage to plants either directly by sucking out their juice or indirectly by transmitting a plant virus (read more here).
The really bizarre thing about aphids is that they are farmed by ants. The ants are milking aphids to harvest the honeydew nectar produced by the aphids. Watch the video for a spectacular demonstration how ant farmers protect their “cattle” from a ladybug predator!
I am sure you will be happy to hear that I found a song about wheat, Russian aphids and research carried out to deal with them!