Aphrodisiac virus makes plants super-attractive to bumblebees

Plants are known to emit volatile chemicals that deter herbivores or attract pollinators or seed dispersers. Some viruses can change those volatiles to attract insects, such as aphids, that damage plants but help transmit the virus between them. 

Now, a team of researchers lead by John Carr from the University of Cambridge has shown in greenhouse experiments that a cucumber mosaic virus can change the types and amounts of chemicals emitted by an infected tomato plant, so that it attracts more bumblebees to pollinate it. As a result, the plants in their experiments produced more seeds.

Without pollination, the virus affected the plants negatively, decreasing their seed production, compared with non-infected plants. But when bumblebees were present, it had the opposite effect.

When the researchers then modelled what would happen under natural conditions, they found that such viruses could indeed enhance plant attractiveness to pollinators enough to make up for loss of fitness due to infection.

This means that the benefits of the virus could outweigh the drawbacks, allowing genes for susceptibility to persist in plant populations.

“To my knowledge, this is the first evidence that virus infection can make plants more attractive to pollinators,” says Carr.