Importance of wild bees routinely underestimated

Bienen6Translated from this original article.

To educate the public in the topic of wild bees, one easily recognizable variety with an especially interesting way of life has been elected since 2013 as „Wild bee of the year“ annually.

Studies give an insight into what wild bees can achieve.

Wild bees are largely unknown to the general public. Starting in 2013, the Wildbienen-Kataster (wild bee cadastre) committee of the Natural History Museum in Stuttgart, the Baden-Württemberg State Institute for the science of bees as well as the beekeeping associations of Baden and Württemberg, have presented representatives of wild bees, whose way of live is especially interesting and who are easily recognised by lay people. Last year, this was osmia bicolor, this year the European wool carder bee was selected as the wild bee of the year.

Only nine of the 25000 bee species worldwide are honey bees, of which eight hail from Asia and one from Africa. Wild bees usually do not form hives but live as solitaries. One exception are the bumblebees who form small annual colonies. Wild bees do not produce combs or honey but are still invaluably important to us. Tomatoes, apples, prunes and almonds – everywhere in the world crop plants have to be pollinated by wild insects too.

An international study led by the Leuphana University of Lüneburg, the University of Würzburg and the University Rio Negro in Argentina examined the influence of the honey bees and wild bees on pollination. In more than 600 cultivated plots in 19 countries on different continents, researchers recorded frequency and diversity of flower-visiting insect species.

The findings were astonishing, since in all cases the wild insects had a positive effect on fruit setting, the turnover of blossoms into fruits and partly the fruit size as compared to crops pollinated by honey bees exclusively.

Seidenbiene (Colletes similis)

Wild bees seem to „work“ more efficiently.The are often smaller – some species measure only a couple of millimetres – and can penetrate blooms more easily, they also do not glue together the pollen they collect and so can more easily attach it to the stigma of a blossom. Furthermore, they visit shadow blossoms, while honey bees prefer sunlight blossoms. Wild bees also pollinate in adverse weather and at different times of the day as honey bees.

The honey bees appear to complement the pollination carried out by wild insects. To obtain optimal crop yields both types of bee should be taken into consideration, since the common practice of deliberately placing honey bee hives near crops like canola, sunflowers, orchards, among others, only produces a basic yield. Honey bees will pollinate these monocultures, which are not sufficient to serve as a solid basis of nutrition for wild bees, however. Those bees depend on biodiversity for food and shelter. Both cannot be too far apart, because wild bees build their nests at a distance of not more than a couple of hunded metres from the flowers they visit. Conditions like these are not provided in modern cultivation areas of industrial agriculture, there is little space for blooming plants at the edges of fields or even within them, because every square inch has to be used for profit. We need the protection and the development of natural habitats, landscapes full of blooms, flower strips, hedges and varied crop rotations to sustain wild pollinators.

Agriculture could produce higher and more stable yields, if the pollination contributions of wild insects were optimally utilised. Economists and ecologists have calculated the global value of pollination by insects in 2009 to be 153 billion €. An incentive sufficient to meet the wild bees‘ needs much more than hitherto.

JPK WieseThis already happens in small scale experiments, for example in the Upper Rhine area in Baden-Württemberg. Those familiar with this region know that large areas there are covered with corn monocultures, a fact which has only changed recently with the infestation of crops with the corn rootworm. As a consequence, the ministry of agricultre ordered farmers to implement crop rotations, which meant that corn could only be grown on the same land for two consecutive years, while afterwards a different crop had to be sown there. Within the experiment mentioned, two farmers volunteered to sow flower mixtures on several experimental plots. Biologists examined the attractiveness of these areas for wild bees (bumblebees and solitary bees). Of course, honey bees also profit from this new supply of blossoms. The researchers could demonstrate a significant increase in numbers of wild bee species observed, among them some species with specific demands on food supply offered by flowers and some red listed species.

The study will continue into 2015 and shows that it is in fact possible and also advisable to promote wild bees to obtain a stable community of flower-visiting insects.

Further information (german): http://www.wildbienen-kataster.de/login/downloads/wb2013.pdf und http://www.wildbienen-kataster.de/login/downloads/wb2014.pdf

Netzfrau Jutta P. Klatt

Translated by Angela Carstensen

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