Apathetic aphids – which become accustomed to ignoring genetically engineered chemical alarms in plants and alarms sent by fellow aphids – become easy prey for ladybugs, according to researchers at the Boyce Thompson Institute for Plant Research and Cornell University.
Under normal circumstances, when a ladybug captures and bites into an aphid, the victim releases an alarm pheromone called beta-farnesene, prompting nearby aphids to walk away or drop off the plant. When aphids are raised on plants genetically engineered to emit beta-farnesene, they become accustomed to the chemical and no longer respond to it – even when a predator is present – making them easy prey.
Aphids reared continuously on genetically engineered Arabidopsis thaliana plants that produced beta-farnesene became habituated to the pheromone within three generations and no longer responded to the compound. In the absence of predators, the habituated aphids produce more progeny, likely because they expended less energy on running away and focus more on feeding compared to normal aphids.
When researchers put ladybugs into the mix, the ones that were habituated to the alarm pheromone get eaten more.