Drought destroys grazing, reducing the number of bee colonies

10. 7. 2020 -

In recent years, domestic farmers have increasingly grown plants that produce less nectar. Bee grazing is also declining due to severe drought, especially due to rising temperatures. In the future, it may weaken bee colonies, even more, says Antonín Přidal from the Department of Zoology, Fisheries, Hydrobiology and Apiculture, Faculty of Agriculture, Mendel University in Brno.

Scientists around the hives have been measuring temperatures for a long time. "In the last 10 years, breaking the top records has become more and more common. The episodes of heat are getting longer every year," says Přidal, who advises beekeepers to ensure grazing by planting honey trees, such as willows, fruit species, and lindens.

On the contrary, according to Pridal, the disadvantages in cities are often mown lawns and planting ornamental trees, such as sakura, which have nectar at all. In recent years, Czech farmers have also more often chosen crops that give less nectar than the original ones. An exception is not rape, for which currently cultivated varieties are in many places completely insignificant in terms of providing nectar and pollen. In addition, rapeseed is associated with its excessive use of chemicals, as a result of which bee colonies weaken and have problems with the creation of the subsequent winter condition and resistance to viruses.

Beekeepers have had to deal with significant deaths after this winter. The mite population graduated in 2019 and participated in the distribution of dangerous bee viruses. Experts estimate that about a fifth of the hives has died. In the Czech Republic, there are almost 800,000 hives and more than 60,000 beekeepers. Both numbers are record-breaking within the planet.

Mites cause varroosis, in which bee viruses also spread. "The problem is the transmission of viruses by the external parasitic mite Varroa destructor. Viruses have recently had increasing virulence, and the damage is becoming more and more frequent. Even timely suppression by natural substances such as organic acids may not bring a solution, as has been the case so far," says Přidal, who, together with experts from CEITEC MU, also participates in clarifying the structure of bee viruses. "We are also involved in verifying procedures for improving the condition of bee colonies," said Přidal.

They also had to deal with the deaths of bee colonies at the MENDELU beekeeping department. This year, they lost more than half of them during the winter, early spring, and spring. "At the time of the quarantine measure, workers and students had time to analyze dead bees and rescue the remaining hives. Even so, some research data was partially lost," Pridal added.