A recently published international study discovered a new role played by bacteria living in pea aphids: they suppress the defences of the plants the aphids feed on. As a result, fewer enemies are attracted to the plant's distress signals, thereby increasing the aphid's chance of survival. The joint study, carried out by Wageningen University & Research and the University of Oxford, was published in the leading scientific journal Nature Communications.
When a plant is threatened by aphids, it defends itself by releasing a blend of volatiles that attracts the insect's natural enemies, such as predatory wasps. The plant uses this so-called 'bodyguard recruitment' to defend itself against attacks.
The study in Nature Communications found that the pea aphid's bacterial symbionts increase the insect's chance of survival by manipulating the plant's phyto-hormonal responses. In other words: the bacteria suppress the plant's distress signal in some way. The study thereby revealed a new mechanism by which the bacteria – known as symbionts – help aphids. It also revealed the importance of studying the insect microbiome (intestinal flora) in order to understand the interaction between different species.
Environmentally friendly pest control
Aphids are among the most important pests for temperate crops, and understanding the relationship between aphids and their bacterial symbionts may assist in the challenge of designing more environmentally friendly pest control strategies. These strategies may include determining the prevalence of protective symbionts in aphid populations and selecting plant varieties which, once attacked by aphids, maximise the attraction to the natural enemies of aphids.
This study was a collaboration between the Laboratory of Entomology at Wageningen University and the Department of Zoology at the University of Oxford (UK) and was financed by the EU Marie Curie programme.