While many people are familiar with the picture of a beekeeper blowing clouds of carbon dioxide into a hive to calm the insects, little is known about its other impacts on bees. Insights into the chemical compound’s effects on bee physiology, especially reproduction, have recently come to light through research.
The research group, headed by an entomologist from Penn State’s College of Agricultural Sciences, sought to understand how carbon dioxide appears to circumvent diapause, a stage resembling hibernation in which bees sleep over the winter, to start the reproductive process in bumblebee queens.
The scientists discovered that carbon dioxide first altered metabolism, which then had unintended consequences for reproduction.The results, which were just published in Insect Biochemistry and Molecular Biology, were in direct opposition to earlier theories.
According to Etya Amsalem, an associate professor of entomology, “Previously, it was thought that CO2 directly affected reproduction, but our work provides some of the first evidence suggesting this is likely not the case.” “We discovered that CO2 alters how the body stores and distributes macronutrients. “The fact that the reproductive process is subsequently triggered is only one of these processes’ byproducts.”
Researchers found that carbon dioxide is frequently employed by beekeepers and scientists to tranquilize bees and other insects. But carbon dioxide can also cause a number of other physiological reactions in addition to having a soothing impact.
For instance, even though bumblebee queens usually go into diapause in the winter before beginning a new colony in the spring, beekeepers and researchers often utilize carbon dioxide to force the queens into reproduction earlier than they would naturally.
Amsalem stated that she and the other researchers sought to undertake the study for a variety of reasons. First, she stated that because carbon dioxide is so widely utilized, it is crucial to comprehend how it affects insects, particularly bumblebees, whose colonies can be produced in commercial apiaries to provide year-round pollination. The second goal was to comprehend carbon dioxide use’s potential impact on study outcomes.
Carbon dioxide can affect conduct as well as other things, according to Amsalem. What are you really investigating, then, if you’re looking at how a certain manipulation affects bee behavior and you’re also using CO2 as an anesthetic? Is it the result of your manipulation or the result of CO2?
The experiments for the study were run in two stages by the researchers. The scientists’ first goal was to gain a deeper fundamental understanding of the physiological effects of carbon dioxide on bumblebee queens.
The researchers divided the bees into two groups: those who received no treatment and those who received carbon dioxide treatment.After that, the researchers looked at the bees at three different times: immediately following the treatment, and then three and ten days later. The scientists looked at the ovaries and assessed the concentrations of various tissues’ macronutrients at each timepoint, which provided information regarding changes in metabolic function throughout time.
In comparison to untreated queens, CO2-treated queens showed higher levels of ovarian activation, according to Amsalem. The distribution of macronutrients changed for treated queens as well, with more protein and glycogen (a kind of glucose stored in the body) in their ovaries and less lipid in the organ known as the “fat body.”
The researchers next intended to dissect how carbon dioxide impacted both metabolism and reproduction using this baseline knowledge. A juvenile hormone antagonist was utilized to treat one group of queens that had their ovaries removed, while carbon dioxide was used to treat two further groups of queens.
According to the researchers, this antagonist lowers the bumble bees’ levels of juvenile hormone, which controls reproduction and speeds up metabolism. The researchers hypothesized that this hormone may play a significant role in how carbon dioxide may influence the physiology of insects.
This time, they discovered that the macronutrient changes in the ovaries-removed bees were comparable to those in the ovaries-remaining bees in the control group. Since bees without reproductive organs still had the same effect, the researchers claimed this demonstrated that carbon dioxide affects the metabolism first.
Furthermore, juvenile hormone inhibitor-treated bees did not display these metabolic changes, which, according to the researchers, supports the hypothesis that this hormone mediates the effects of carbon dioxide.
Amsalem stated that the results are crucial for comprehending how carbon dioxide impacts all insects, not just bumblebee queens.
According to her, “CO2 has a variety of affects on insects, therefore, as scientists, we’re attempting to find an effect they all share so we can identify the particular procedure or method causing these effects.” “For instance, it may promote reproduction in bees while preventing it in other insects.” It has varying effects on reproduction, which are inconsistent. However, we believe that it consistently modifies metabolism.
Eran Levin, a researcher at Tel Aviv University, and Katherine Barie, a former graduate student at the College of Agricultural Sciences, also took part in this work.
This study was made possible in part by the United States-Israel Binational Agricultural Research and Development Fund.
