02. August 2018

No apples without bees

Bees and other insects that pollinate blossoms are indispensable for fruit and vegetable growing. In recent years, however, reductions in bee populations have increasingly been observed in fruit-growing areas.

Bees as an economic factor

The value of bees and other insects that pollinate blossoms has been documented by researchers here and abroad and is now widely known. International studies have shown that at least 75% of fruit-tree blossoms are pollinated by bees. The bee lands on the flowers to collect nectar; pollen then sticks to its fine hairs. This pollen then fertilises the next blossom that it visits. Bees thus ensure the continued existence and yield of almost all types of fruit. Without bees, the fertility of most fruit trees as well as the seed production of many plants would be greatly diminished. The work of bees and their colleagues therefore also has a high economic value. The value of pollinating insects – including wild bees, butterflies, ground beetles and others, as well as honey bees – is, according to a TEEB study*, worth over 150 billion euros worldwide and around 22 billion euros in Europe alone, a number that underscores the importance of bees.

Decline in bee populations

In recent years there has been a decline in the bee populations in many areas around the world. The phenomenon of entire bee populations disappearing was first observed in the USA in 2006, with bees flying away from the hive and not returning. The result is that the queen and the young bees all starve. In Germany, many colonies die each year, especially during the winter months, while bees have already disappeared from large parts of China, requiring humans to take on the hard work of pollination by hand.

Seeking the cause

Scientists have not yet been able to definitively identify the exact cause of bee die-offs. Food shortages, loss of habitat, an absence of nesting sites as well as exposure to chemicals are all suspected. Honey bees also face increasing problems of disease and parasites. Many research institutes are looking into the problem in order to discuss the relationship between fruit production and the development of bee populations, so as to understand this and develop appropriate solutions. The “Apistox” project conducted over three years (2014-2016) by the Laimburg Research Centre in Bolzano, South Tyrol, examined the impact of pesticide use in fruit-growing on bee colonies during foraging. No direct correlation was observed between the increased use of insecticides and low colony growth, but damage to secondary flowering was recorded. The lack of honey yield following apple blossoming leads the bees, after the bee conservation period, to fly back and look for flowers in the understorey of apple orchards. They then come into contact with plant protection agents that can cause increased bee mortality. It would however be too easy to blame bee deaths on fruit-growing, as orchards in fact provide bees with a habitat and a honey yield. Varroa mites undoubtedly share responsibility for bee deaths. Originating in Asia, these arrived in Europe some 35 years ago. They drink the blood of bees and reproduce on the brood, so that young bees emerge from pupation in an already weakened condition and die a short time after. A colony that is heavily infested with the Varroa mite will decline, with individuals flying to the next colony and infecting it with mites, causing the vicious circle to repeat itself.

Preventive measures

Even if the causes of bee deaths are still not fully understood, farmers are advised to take extra precautions. Without pollination by bees the apple yield would be reduced by some 2/3 and fruit quality would also be negatively affected. Every farmer thus has an obligation to do everything possible to protect these precious insects. The following measures will help protect bees when treating apple orchards with plant protection agents**:

  • No spraying of blossoming plants: when bees are not foraging there should be no spraying of blossoming plants with agents that are harmful to bees. •    Low-loss spraying: modern low-loss spraying technology can prevent drift onto blossoming plants.
  • Choose the right time of day: when bees are not foraging, agents that are harmful to bees should if possible be used in the evening hours, after the bees have ceased their daily flight activity, or at night or the early hours of the morning: the danger of bee poisoning is considerably lower if the spray has already dried.
  • Mulch the understorey: mulch the blossoming understorey before any treatment with agents that are harmful to bees. This too should be performed if possible outside bee flight times, as many bees are attracted to flowers on the understorey.
  • Never spray onto blossoms: harmful agents may not be used once the first flowers have opened and before the trees have completely ceased blossoming.

*TEEB (The Economics of Ecosystems and Biodiversity) is a research initiative that aims to highlight and implement existing approaches to the economic valuation of biodiversity and ecosystem services.

** Excerpt from recommendation by the South Tyrol Farmers’ Association “Der Biene das Leben erleichtern [Making life easier for the bee]”.

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