A plant virus has developed the trick of attracting bees to the plants it has attacked to make sure they produce plenty of seed.
This clever tactic means that bees fertilise the diseased plants, rather than healthy ones, and so ensure the survival of future generations of both the plant and the virus.
Scientists at the Cambridge Global Food Security Initiative (CGFSI), who are studying the phenomenon, have realised that if they can discover the virus’s secret they will be able to attract bees to food crops and produce better yields − thus increasing the chance of feeding a world faced with climate change and an ever-growing population.
The quest has become more urgent because bee numbers have dwindled due to pesticide use and honeybee colony collapse disorder.
“Bees provide a vital pollination service in the production of three-quarters of the world’s food crops,” says the study’s principal investigator, Dr John Carr, head of the University of Cambridge’s Virology and Molecular Plant Pathology group. “With bee numbers in rapid decline, scientists have been searching for ways to harness pollinator power to boost agricultural yields.”
The virus that has developed the trick of attracting bees is the cucumber mosaic virus, which, as its name implies, was first discovered in cucumbers, but is very successful and infects many plants and crops. It is particularly disruptive for tomato growers because it makes the plants smaller with less tasty fruit.
Bees provide a vital pollination service in the production of three-quarters of the world’s food crops.
John Carr, head, Virology and Molecular Plant Pathology, University of Cambridge
This would normally mean that healthy plants would outcompete the diseased ones and the virus and its hosts would die out. But this does not happen. And, after eight years of study, the scientists have discovered why: the virus gives off a special scent that makes bees head straight for the diseased plants and fertilise their flowers, in preference to healthy ones.
A series of experiments at Cambridge University Botanic Garden, with the collaboration of its director, Professor Beverley Glover, were carried out in specially created bee flight areas. They demonstrated time and time again that bees released in the tunnels homed in on the plants infected with the virus.
Cambridge University scientists then managed to isolate the organic chemical compounds the plants emit, and so discovered what attracted the bees. They liken it to humans using perfume or aftershave to attract a mate.
Having cracked one problem, Dr Carr has realised that there is another. “I am thinking about the bees,” he says. “There has to be something in it for them. If they do not get a benefit, by getting plenty of good food in either pollen or nectar, they are not going to be fooled for long.”
So as well as being able to reproduce chemically the enticing smell that is attracting the bees, the scientists have to make sure that the bee gets a proper reward when it fertilises the target crop.
This has been achieved by scientists attempting to train bees for other tasks, such as smelling out explosives or drugs, by adopting a simple formula of rewarding the bees with a drink of strong sugar solution when they complete their task. Thus, the bee is happy to home in on something it cannot eat because it is immediately rewarded.
So the research is continuing in Cambridge − in conjunction with Rothamsted Research in Hertfordshire, England, and the UK’s Royal Horticultural Society − with scientists now concentrating on how to reward the bee when it does its job and visits the food crop the farmer wants it to.
This story was published with permission from Climate News Network.