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The Case of the Missing Bees: Study Shows a 25% Decrease in Wild Bee Species Across the Globe

Despite weighing less than a tenth of an ounce, bees have an immensely large impact on humans and the foods we consume, pollinating nearly 85% of all cultivated crops, such as blueberries, kale, and coffee to name just a few. Yet for insects who contribute so much to our pantries, a 2021 study published in the scientific journal One Earth discovered an enormous drop in the number of bee species reported globally. From 2006 to 2015, every continent, omitting Australia, has seen an alarming 25% decrease in wild bee species since the 1990s.

Utilizing the Global Biodiversity Information Facility’s citizen scientist run database, Eduardo Enrique Zattara, the study’s author, tracked and analyzed records of bee sightings over the past 120 years. Hundreds of thousands of photos and taxonomic records, taken by both amateurs and scientists alike, were collected. They were then separated by year taken or sampled and, depending on which of the 20,000 global bee species was depicted, categorized, and graphed accordingly.

Initially surprised by the rapid decline of species in the past few decades, Zattara verified his data was accurate by eliminating alternative causes of the phenomena. One of these alternative hypotheses is that fewer people are documenting bee species, leading to fewer data inputted into the Global Biodiversity Information Facility. Another is the possibility of observer bias — a citizen searching for a particular species in the field could fail to note others found beside. While these alternative explanations are possible, Zattara assures, “none of the artifactual trends caused by potential observation biases in the data are stronger than the real trends in bee diversity” (115).

Photo by Laura Lauch on Unsplash

Thus, Zattara confirms global bee populations are indeed decreasing at an ever-accelerating pace. Over the past ten years alone, bee species have experienced a startling reduction of as much as 25 percent. “In the best scenario, this can indicate that thousands of bee species have become too rare; under the worst scenario, they may have already gone locally or globally extinct,” Zattara writes (120). Many factors could induce these drastic disappearances such as climate change, bee pathogens, and increasing land use transformation, which in turn can lead to the homogenization of bee habitats and higher use of harmful pesticides.

Undoubtedly, the dramatic loss of bee species, whether a result of increasing rarity or extinction, requires immediate and extensive action. Promising initiatives, such as the United States’ recently proposed national bee monitoring program, can contribute to global databases and spur further research on a global scale. Reversing habitat destruction, widespread re-flowering programs, and an international move towards environmentally-friendly farming can be significant steps to restoring bee habitats. Furthermore, citizens can become scientists in their own communities by contributing to databases such as the Global Biodiversity Information Facility used in this study. Every action supporting the preservation of wild bee species, regardless of how big or small, is nothing less than essential. With the establishment of these efforts, we will ensure the vital presence of bees in our natural ecosystems, in our agricultural goods, and, most importantly, in our future.

Photo by Markus Winkler on Unsplash

Be(e) Part of the Solution! -



Zattara, Eduardo E., and Marcelo A. Aizen. “Worldwide Occurrence Records Suggest a Global Decline in Bee Species Richness.” One Earth, vol. 4, no. 1, 2021, pp. 114-123.


Written by Abby Radunz

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