Why Do Bees Need Nectar And Pollen?

Why bees need nectar and pollen and how they use it 

It’s well known that bees gather these products from flowers, but why do they need them - what are the specific benefits to bees?

Basically, nectar provides an important energy source (carbohydrate) – it supplies a complex range of sugars, whilst pollen gives vital protein and fats.

Although all bees need pollen at some stage in their lives, not all bees gather it.

Male bees do not collect pollen, and have no pollen baskets (corbicula) with which to transport it from flowers to the nest or hive.

Cuckoo species – such as cuckoo bumble bees also do not gather pollen, since they also have no pollen baskets, however, they do require it, but rely on the host bumblebee species to supply their needs.

So let’s look at the requirements of the different types of bees.

The role of nectar and pollen in bumble bee and solitary bee colony development

Queen bumble bees will very quickly seek nectar when they emerge early in the year – usually it will still be cold, and the bumble bee queen will need to boost her energy resources very quickly.

She will then forage for quality pollen from pussy willows, winter flower bulbs and other good bee plants.

Queen bumble bees will have been impregnated the previous year, and will hibernate whilst fertile. Consuming pollen is believed to help her ovaries ripen. 

Once she has found a suitable nest site, she can then gather provisions ready for developing larvae, and then lay her eggs. The provision she has made for the developing larvae, will contain vital protein in the form of pollen.

Whilst incubating her eggs, the bumble bee queen will need to keep up her own energy reserves. In order to do this, she will have provisioned herself with a small pot of nectar from which she will feed herself.

As the young bumble bees hatch, they will continue to feed until they are ready to assist in the nest.  When they are ready, the females will venture out of the nest as workers, and will gather more nectar for feeding the adult bumble bees, and pollen for the rearing of the next bumble bee brood.  

Solitary bees also provision each separate egg cell essentially with a pollen mixture, that the developing larvae will consume as they grow. However, once the female solitary bee has performed this task, she will have no further involvement in rearing the next generation of solitary bees.

Honey bees need nectar to make honey 

Honey bees need nectar and pollen for much the same reason as bumble bees and solitary bees, although they treat it slightly differently.

The nectar that is gathered by honey bees is taken back to the nest or bee hive.

Of course, it is used to feed adult bees, but it is also passed from foraging worker bees to worker house bees, and then is deposited into honeycomb cells.

After a process of fanning and evaporation, the nectar will turn into honey, and will be capped over with wax by the bees. Now that this nectar has been turned into honey, it will provide a winter food source for the bees to dip into when they are unable to forage outside for food.

You can read more about this, in How Do Bees Make Honey, and Why Do Bees Make Honey?

Of course neither bumblebees nor solitary bees store nectar in this way (i.e. as a winter food store), since their life cycles are entirely different, and shorter than that of honey bees (although the lifespan of individuals within colonies varies and can also be short for honey bees – see How Long Do Bees Live?).

Where do honey bees store pollen?

Pollen is again crucial for honey bee brood development, and is made into bee bread.

The pollen is mixed with water and nectar from the bee’s mouth, which causes the pollen granules to ‘grow’. The bee bread is then stored in honey combs, and even helps to add a certain amount of structural integrity to the comb itself.

How do bees collect pollen?

How bees collect pollen depends on the species.

Pollen is collected and carried by many bee species on hairs of the hind legs called 'scopa'.  

On honey bee and bumble bees, the hairs on the hind legs         as specially adapted to form pollen baskets known as 'corbiculae'. 

It is also collected on the furry coats of the bees.

As bees fly through the air, their bodies become positively charged with static electricity, such that when the bee lands on a flower, knocking the pollen from the delicate anthers, the pollen particles stick to the static-charged hair covering the bee's body.  The bee becomes covered in pollen, and uses its legs to wipe the pollen from its body into a sticky mass, which now sticks to the inside of the back legs.  The bee then uses its back legs to compress the pollen further and move the little masses of pollen into the corbicula on each leg.  Once the bee returns to its hive or nest, it deposits the pollen into an appropriate cell.

However, some species, like this leafcutter bee above, collect pollen on the hairs located on the underside of the abdomen.

Buzz pollination

In some cases, bees may have to literally 'shake' the anthers by grabbing hold of the anther and vibrating their flight muscles, such that the vibration causes the pollen to be released.  This releasing of pollen is accompanied by a 'buzzing' sound, a little different from the sound the bees usually make, and enables 'buzz pollination' (or 'sonication') to occur. 

Bumble bees and some solitary bee species, are especially effective at buzz pollination (honey bees do not buzz pollinate), and this form of pollination is especially useful for some food crops such as tomatoes.

Providing sources of nectar and pollen for bees

It's not surprising that bees need good sources of nectar and pollen throughout the year, to cope with the rearing of broods, development of colonies, and because different species are more active at certain times of the year than others.

Wildflowers are increasingly important due to major losses of natural wildflower landscape.

However, the tremendous choice of herbs, cottage garden plants, fruit, vegetable plants, trees and shrubs which can be grown even in small spaces, offer plenty of opportunity for people and their communities, to play their part in helping pollinators.

See these lists of plants for bees for more information.

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