Only a small number of bee species pollinate major crops in the United Kingdom, but researchers believe protecting rare bees and insects will help protect against food shortages in the future.

Protecting a wider variety of pollinators would provide farmers with a "reserve squad" to ensure future food security, the University of Reading reported. Improving bee diversity in Britain would create an "insurance policy" against future ecological variations related to climate change.

"The few bee species that currently pollinate our crops are unlikely to be the same types we will need in the future," said Professor Simon Potts, director of the Centre for Agri-Environmental Research (CAER) at the University of Reading. "It is critical to protect a wide range of bees and other insects now so that, as Britain's climate, environment and crop varieties change, we can call on the pollinating species which are best suited to the task. We can't just rely on our current starting line-up of pollinators. We need a large and diverse group of species on the substitutes' bench, ready to join the game as soon as they are needed, if we are to ensure food production remains stable."

The researchers pointed out that the majority of Britain's endangered pollinators are considered "valueless." The major pollinators, such as bumblebees and solitary bees, are worth about $3,000 per hectare.  Only about 2 percent of potential bee species make up 80 percent of crop flower visitors observed in the study. These bees are essential for the production of crops such as "oilseed rape, beans, apples and strawberries," and replacing their work would cost upwards of £1 billion a year in the U.K.

"Human history is full of examples of food crises caused by an over-reliance on a single crop or a dwindling number of species," Potts said. "In the insect world, we have already seen how the massive decline in honeybees in Britain has led to a reliance on wild bees to do much of the pollination. At one time, honeybees were enough to pollinate most of Britain's crops. Now, there are only enough to pollinate around a quarter of them. If we didn't have other species of bees to turn to, we would already be facing a food security catastrophe."

Honeybee colonies in the U.K. have fallen from 250,000 in the 1950s to fewer than 100,000 today.  The pollinating species for certain crops have also shifted. British apple crops used to rely primarily on honeybees for pollination, but are now almost exclusively pollinated by a few wild bee species.

"Putting a cash value on ecosystem services is helpful to highlight to politicians and farmers just how important nature is to the bottom line. But thinking purely about today's profits is pointless if it comes at the expense of the future sustainability of our countryside and our food supply," Potts said.

The findings were published in a recent edition of the journal Nature Communications.