Like most bees, bumblebees have it tough. They are fighting a battle against pesticides, habitat loss and parasites. This has ensured a sharp decline in their stocks. Up to 75 percent of the species has disappeared in certain places. Now scientists have discovered another threat. Global warming can give bumblebees breathing problems. These results were recently presented at an annual meeting of the Society for Integrative and Comparative Biology. – This study shows that some bumblebees are very vulnerable to changes in the climate. That’s what John Hranitz says. He is an ecological geneticist, studying bees at Bloomsburg University in Pennsylvania. Sees a trend The new study was carried out by researchers in the USA. They believe that approximately half of the country’s 45 bumblebee species are in trouble. Although climate change is most likely a contributing factor, the full reason why it has become so is still not known. But it is supposed to be the more specialized species, with longer tongues, which tend to disappear. And this causes concern. Because if these bees disappear, the flowers that depend on them will also be in danger. The reduction of these species can make the flower meadows less colourful, and more importantly – it can lead to major problems for entire ecosystems. Farmers also depend on the bumblebees to pollinate crops. Bumblebee death can have consequences for entire ecosystems, the researchers write. As temperatures rise, populations decrease. Photo: Kaj Hjertenes / news Collected queens Eric Riddell is a biologist at Iowa State University. Together with colleagues, he wanted to find out why climate change affects some bees, while others tolerate it better. Therefore, the researchers collected and studied local queens belonging to the species Bombus auricomus. A species that is in decline. In addition, they studied one of the species that seems to be doing well (B. impatiens). The insects were collected as they emerged from hibernation to build nests. In the laboratory, the bumblebees were allowed to live under conditions that they would have encountered outdoors. Both soils and temperatures were simulated. Were placed inside glass tubes To test the queens’ response to temperature, they were placed inside glass tubes. There, the researchers tracked how fast the insects breathed and how much water they lost. The hops were tested at 18 and 30 degrees. In this way, Riddell’s group could study the many ways that warming can affect a bee’s physiology. This must not have been done previously. At 18 degrees, the queens of both species took about one breath per hour. When the scientists turned up the thermostat, the endangered species completely transformed. It began to breathe ten times faster than before. – It’s almost like hyperventilating, explains Eric Riddell. That’s why bees are important In many parts of the world we are seeing a dramatic decline in the number of bees and other insects. Species disappear and they become fewer. A study from 2017 reported that the amount of insects in German nature reserves had been reduced by 76 percent over the course of 27 years. Insects are important for pollination, i.e. pollination of plants. This is necessary for plants to reproduce. Bees are our most important pollinators. Agriculture is completely dependent on bees in the production of food, vegetables, oil crops, fruit and berries. According to the International Panel on Nature (IPBES), around 75 percent of agricultural crops in the world depend on pollinators. The value of pollination globally is estimated to be around 351 billion dollars, (IPBES). 5 – 8 percent of global agricultural production depends on pollination. There are 20,000 bee species, 208 of which we have in Norway. One in three species, including the bumblebee, is threatened with extinction. 12 of our species are probably gone for good. Changing habitats, climate change, pesticides and disease threaten the bees. (Sources: The Assessment Report on Pollinators, Pollination and Food Production, IPBES and Sabima) Things are a little better in Norway Frode Ødegaard is an associate professor at the NTNU Science Museum. He himself has researched bumblebees, and together with colleagues has found that almost half of the species in Europe are at risk of disappearing within the next 100 years. He says it is a well-known fact that bumblebees are struggling as a result of a warmer climate. – The new study says something about the physiological mechanisms that cause them to struggle. That is, they hyperventilate to get rid of heat and then use more energy. But the decline among hops is complex, Ødegaard explains. He still thinks the research is important. – Yes, it is important to understand the problem at all levels. But I’m not surprised since bumblebees are largely an insect group adapted to cool climates. Bumblebees are therefore better off in Norway. Nevertheless, you can also see here that the little pilots are struggling. A total of 6 of our 35 bumblebee species are listed on the Red List 2021. Including tundra bumblebee and polar bumblebee, both of which are found in the high mountains and are threatened by a warmer climate. Frode Ødegaard, insect researcher and associate professor at NTNU Science Museum Photo: Liv Ødegaard Thinks to see a pattern So back to the American experiment. After three days into the project, 25 percent of the species, which is not threatened with extinction, died. Twice as many of the species Bombus auricomus had to pay with their lives. This could be an explanation for why some populations are dying little by little, as the world gets warmer, explains Eric Riddell. However, the researchers cannot determine that this is the reason why more and more bumblebees are disappearing. But they think they see a pattern. Because in addition to the two species the study is about, the researchers have also carried out the test on other bumblebee species in recent times. The populations that decrease in number are also those that begin to hyperventilate at higher temperatures, says Riddell.
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Some bumblebee species can hyperventilate when temperatures rise, new research shows – news Trøndelag
