Biological invasions are a major driver of biodiversity loss and invasive pollinators can reshape native plant-pollinator networks. A new study published in the journal NeoBiota , reveals that invasive pollinators are fundamentally reshaping native plant-pollinator networks in Chile, leading to a "silent takeover" that threatens the stability of one of the world's most unique biodiversity hotspots.
Chile functions as a "biogeographical island," isolated by the Andes Mountains, the Atacama Desert, and the Pacific Ocean. While this isolation has created a highly specialized ecosystem, it also makes the region particularly sensitive to change.
Despite this vulnerability, Chile has a long history of introducing non-native bees for agricultural purposes. A collaborative team of Chilean and Brazilian researchers sought to understand and quantify the long-term impact of these introductions, specifically focusing on how non-native pollinators like Bombus terrestris (the buff-tailed bumblebee) affect native species.
Tracking the "Silent Takeover"
To assess the impact, researchers analyzed over 2,100 records, merging historical scientific data with citizen-science data. They focused on three non-native species: the western honeybee (Apis mellifera), the buff-tailed bumblebee (Bombus terrestris), and the large garden bumblebee (Bombus ruderatus).
"The motivation was to understand whether these invasions were simply adding species to the system or quietly transforming it from within," explains Dr. Rafaela Cabral Marinho, the lead author of the study.
The study's key finding points to the overwhelming dominance of Bombus terrestris, which accounted for more than 70% of recorded interactions in the combined dataset. "That level of integration into a national pollination network is remarkable for a relatively recent invader," notes Dr. Barbara Guimarães, one of the researchers.
Furthermore, the invasive bees showed strong interaction with non-native plants and displayed highly generalist behavior. To further measure the impact on pollination networks, the team compared data from before and after 2005, the year B. terrestris began to be used extensively in open fields. They identified a concerning shift: native species like Bombus dahlbomii were being gradually displaced.
The networks did not collapse; instead, they became more generalized and homogenized. Native bees were not always disappearing completely. The system kept functioning, but in a different way. This quiet reorganization is what led us to describe the process as a 'silent takeover. Native bees were not always disappearing completely. The system kept functioning, but in a different way. This quiet reorganization is what led us to describe the process as a 'silent takeover'.
- explain the researchers.
The power of citizen science
The study also highlighted the vital role of public engagement. "We were surprised by the volume and value of citizen science contributions, and how they can provide meaningful insights when combined with research data," says Dr. Fontúrbel, one of the researchers.
This proved that citizen science is an essential tool for detecting and tracking the spread of invasive species in ecosystems, providing direct information for conservation actions.
A call for interaction-based conservation
One key takeaway is that biological invasions are not always catastrophic overnight events. They can be gradual reorganizations of ecological relationships. While invasive bees may increase pollination for certain crops, they can simultaneously reduce the specialization and stability of native mutualisms. Over time, this may lead to biotic homogenization, ecosystems becoming more similar to one another and less unique.
add the researchers
"Our research highlights that conservation is not only about protecting species, but it is also about protecting interactions," they conclude.
The researchers advocate for coordinated policies regarding species introductions, early detection monitoring, and continued public engagement to safeguard the integrity of Chile's biodiversity.
Original source:
Marinho RC, Guimarães BMdaC, Carvallo GO, Maruyama PK, Murúa MM, Rech AR, Vieli L, Oliveira PE, Fontúrbel FE (2026) Silent takeover: How invasive bees reshaped plant-pollinator interactions in a biodiversity hotspot. NeoBiota 105: 259-274. https://doi.org/10.3897/neobiota.105.174573
