Bees need better food

Honey bee nutrition is coming under the microscope as New Zealand researchers find that commonly held ideas about bee drinking and foraging are not supported by research.

It’s been thought, for example, that making a mixture of flowering plants – and even pretty flowers – available to bees enhances their survival and fitness.

But this turns out to be ‘‘seriously flawed’’, according to Steve Wratten, a Distinguished Professor of ecology at Lincoln University, speaking on behalf of a research team led by Dr Morgan Shields and Sarah Cairns.

Those ideas ‘‘suffer from lack of rigorous science in the selection of such flowers, and when and how they are deployed’’, he says.

For example, it’s been thought that phacelia (tansy leaf) provides abundant nectar and pollen to honey bees.

But researchers led by Rowan Sprague of the Bio-protection Research Centre at Lincoln analysed 23,432 visits to phacelia flowers by honey bees and observed that pollen was almost never collected.

Another flower commonly provided to bees – sunflower – is seriously lacking in nutrients needed by bees, with sodium notably in short supply.

Research by others shows that the ‘‘mineral content of pollens is a key factor in maintaining and enhancing bee fitness’’, Wratten says.

Wratten’s team have come up with a research programme that is systematically evaluating the mineral chemistry of pollen in a range of frequently used and rarely used flower species.

They’re collaborating with University of Waikato researchers, who have an Inductively-coupled Plasma Mass Spectrometer that can detect minerals at incredibly low levels.

They hope to identify which flowers best suit honey bee’s nutritional needs.

The ultimate goal is to develop seed-mixture products with commercial seed suppliers. These mixtures, it’s hoped, can be sold to commercial and domestic beekeepers, who will plant them near their hives.

Another option under study is applying common salt to the soil around unsuitable flower species. This could make the pollen more suitable for bees by providing more sodium to the pollen.

Another strand of the research asks why bees prefer ‘‘dirty’’ water over fresh water. Bees have often been observed drinking from puddles, ponds and even swimming pools.

It’s now thought that bees prefer these water sources because of their mineral contents.

In other words, honey bees aren’t getting the ‘‘right’’ mineral mix from many pollens.

It may be possible to provide nutrient-rich ‘‘dirty’’ water to bees in a simple delivery system, such as plastic pottles with wicks placed at the beehive.

This provides a second option for enhancing bee nutrition, especially in winter when few flowers are available.

Beekeepers know about this problem and often give bees sugar in winter, but this research may provide them with a more balanced mix, including the right minerals, Wratten says.

Globally, bee populations have declined over the past 50 years and some species have become extinct, Wratten says.

Managed honey bee stocks are also facing problems in

North America and many European countries, although these stocks are increasing substantially in China and some parts of Australasia.

The declines are probably caused by widespread losses in agricultural biodiversity, bee parasites and pathogens and pesticides, Wratten says.

The research, which is ongoing, is funded by a James Cook Fellowship and other sources, including Bayer in Germany.