Bombus dahlbomii, often called the Patagonian bumblebee, stands out as one of the world’s largest bee species. This magnificent insect, with its impressive size and fluffy appearance, has earned affectionate nicknames like “flying mouse” or “el moscardón” in its native region. It is recognized for its striking, bright ginger-orange coloration, making it a unique sight in the temperate forests of southern South America. This remarkable creature is a native resident of Patagonia, a vast region spanning parts of southern Chile and Argentina.
The Patagonian Flying Mouse
Bombus dahlbomii is truly a giant among its kind, with mature queens reaching up to 40 millimeters (1.6 inches) in length, making it one of the largest bumblebees globally. Its body is predominantly a vibrant reddish-orange, covered in long, dense bristles that give it a distinctly furry appearance. The head, wings, and legs, however, are black, providing a visual contrast to its plush, ginger-colored thorax and abdomen. When in flight, this large bee produces a notably low-frequency buzz, contributing to its “flying mouse” moniker, while in Spanish, it is often referred to as “el moscardón” due to its substantial size.
This unique bee is endemic to the temperate forest regions of southern Chile and Argentina, including the broader Patagonian area. It occupies forest environments that can have both continuous and fragmented distributions of flowering plants, which are its primary food sources. Despite its imposing size, Bombus dahlbomii is known for its notably docile temperament, rarely stinging. This gentle disposition contributes to its endearing reputation among locals and researchers.
Threats from Invasive Species
The rapid decline of Bombus dahlbomii populations is primarily linked to the introduction of non-native European bumblebees, specifically Bombus terrestris and Bombus ruderatus, into South America. These invasive species were initially imported to Chile for commercial agricultural pollination, particularly for crops like tomatoes, avocados, and blueberries. Since their introduction, these non-native bees have established wild populations and expanded their range into Patagonia and Argentina.
One significant consequence is direct competition for resources. The introduced Bombus terrestris and Bombus ruderatus actively compete with Bombus dahlbomii for limited nectar and pollen resources, as well as suitable nesting sites. This competition places immense pressure on the native bee, which is less efficient at foraging quickly due to its larger size and shorter tongue. The invasive species also introduced a deadly protozoan parasite, Apicystis bombi, to which the native B. dahlbomii possesses no natural immunity.
This phenomenon, known as “pathogen spillover,” has devastated native populations. Research indicates that Apicystis bombi was not present in South America before the commercial introduction of B. terrestris in the early 1980s. Once ingested by B. dahlbomii, the parasite’s oocysts inhibit colony formation and prevent essential actions like foraging. Beyond these threats, habitat fragmentation in its native temperate forests acts as a contributing stressor, reducing available resources and increasing isolation for remaining populations.
Race to Save a Gentle Giant
Efforts are underway to address the decline of Bombus dahlbomii and promote its recovery. Scientific research aims to gain a better understanding of the Apicystis bombi parasite’s transmission mechanisms and its specific impact on the native bee’s physiology and behavior. This includes investigating how the parasite inhibits colony formation and foraging activities in B. dahlbomii.
Monitoring programs are actively tracking remaining populations, often employing innovative, non-invasive methods like passive acoustic monitoring (PAM) to collect data on bee sounds and environmental variables. This acoustic data, along with temperature and humidity readings, helps researchers develop machine learning models to identify and track Bombus dahlbomii populations and their interactions with invasive species.
Advocacy efforts are pushing for stricter regulations, or even a complete ban, on the importation of non-native commercial bumblebees into Chile and Argentina to prevent further pathogen spillover and competition. Public awareness campaigns, including citizen science initiatives like “Vi un abejorro” (“I saw a bumblebee”), encourage community engagement by asking individuals to submit photos and sightings of bumblebees, contributing to a broader understanding of population status and invasive species’ advance.