10 September 2015 16:10

1. Just 12 plants feed the world

Globally, over 3,000 different varieties of plants are grown for food in total, but of these thousands of species, just 12 currently supply 90% of the world’s food supply.

These include rice, wheat and maize, and are all wind- or self-pollinated. There are over 2000 crop plants, including most fruits and vegetables that are insect pollinated, and these are the exciting foods that make up the flavour and spice of life.

2. Not just for bees!

Until now research into pollinator nutrition has focused on the honey bee and its consumption of nectar and pollen. There are however, many other pollinating creatures -  for example, butterflies, hoverflies, true flies, birds and even bats are all known pollinators across the world.

Butterflies, hoverflies and true flies all eat pollen as a major part of their diet; however, we need research into the causes of declines that may be happening in these groups.

These animals eat pollen as their primary source of protein, required for growth, reproduction and maintaining immune systems. Pollen are microscopic grains produced within the anthers of flowers and transferred to the stigma as part of plant reproduction.

When pollinating, insects can be seen drinking the nectar that these plants provide, but they are also collecting and eating pollen.

An individual honey bee larva requires about 30mg of protein from pollen in order to grow into an adult, a whole hive of honey bees may require up to 10kg of protein each year to maintain a large population. Pollen also contains other nutrients including fats, vitamins, minerals and small amounts of sugars and starch.

The nectar they drink provides the majority of sugars required for the energy used in foraging activities and general flight.

3. Low-fat flowers

Pollinating insects have different preferences for which flowers they eat from, based on flower shape, colour, smell and taste.

For example, honey bees preferentially visit some flower species over others, preferred species including white clover, common dandelion and plantain. Bumble bee preferences are different between species; many prefer borage, bird’s foot trefoil and red clover. Hoverflies can be seen most often on very open flowers, such as buttercup and pignut.

Not all plant species produce pollen of equal nutritional value; the protein content of pollens has been well documented and has been shown to vary between 12% and 62%. The fat content of pollens also varies between different species too.

4. A beehive is like a kitchen

As bees do not have access to fridges and freezers, when storing nectar inside the hive honey bees convert nectar to honey. This preserves the nectar as a long term food store for times when there aren’t sufficient sources in the wild. Similarly, honey bees also preserve pollen inside the hive by converting it to “bee bread”. Bees store pollen in cells along with a small amount of nectar, which is then fermented to become bee bread.

The fermentation of pollen produces lactic acid, protecting the stored pollen from bacteria and fungi that could rot it. This step also produces a “rind” on the surface of the pollen store, protecting and sealing it physically. These preservation steps are curiously similar to how we produce yoghurts and cheeses.

5. Not all meadows are the same

Different habitats, dominated by particular plant species, offer more nutritious diets for certain insects. For example, a wildflower meadow may favour hoverflies and true flies, brownfield sites may support more butterflies and broadleaf woodlands may be preferred by bumble bees.

Research at Lancaster University has recently found that the composition of environments surrounding honey bee hives can determine the quality of bee bread that they produce. For example, bees near broadleaf woodlands were found to have more protein in their diet, whereas when they are surrounded by arable farmland they get less protein.

The health of a local pollinator community is dependent on a mix of the different species of pollinator, the plants they can feed on and the nutritional content of those plants.  

We desperately need more research into the nutrition available to pollinators in the variety of global habitats and how this matches up to each species’ requirement. With this information we may be able to offer more prescribed and therefore more effective pollinator conservation strategies.

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