- Orchid bees, which help pollinate species from at least 30 plant families and play a big role in Brazil’s agriculture, have long been under threat from land-use change.
- Data from 1996-1997 from the Amazonian state of Rondônia show the twin spread of deforestation and agriculture drove down orchid bee abundance and diversity in this region.
- Analyzed in a recent study, the data suggest that bee diversity and abundance decline after only a decade of land-use change.
- Scientists revisited the past data collected from more than 130 sites to provide a more comprehensive baseline of orchid bee biodiversity as the region continues to face deforestation.
With their metallic-blue-and-green bodies and iridescent wings, orchid bees aren’t just charismatic bugs. They’re specialist pollinators in tropical rainforests from Mexico to Brazil and are primarily responsible for the spread of the iconic Brazilian nut. But orchid bees might also provide a window into how deforestation and land-use change affect ecosystems and biodiversity, a recent study in Brazil’s state of Rondônia suggests.
Although not the only pollinators affected by habitat loss, orchid bees, from the tribe Euglossini, are “among the most spectacular, peculiar, well-known, and economically important pollinators around, and they have the potential to attract the attention of the public and policymakers,” said study lead author J. Christopher Brown, professor of geography and atmospheric science at the University of Kansas, adding the bees might be the “perfect poster child” for conservation in the Amazon.
The research, recently published in Biological Conservation, looks at how land-use change affects orchid bee abundance, richness and composition over time in various sites across the Amazonian state of Rondônia.
The region is marked by its neotropical forests, cattle ranches, and production of coffee, cacao, beans, maize and Brazil nuts. When an area is settled for human use, whether cattle grazing or agriculture, it’s first deforested. This opens up the canopy cover, leaving many of the species that rely on resource diversity unable to find what they need. In the case of orchid bees, which rely on many different food sources, with males frequenting specific plant species to collect perfumes for mating, the loss of plant resources becomes a major problem.
When the data were collected in 1996-1997, Rondônia was among the most diverse regions for orchid bees worldwide. But between 2000 and 2023, Rondônia lost 27% of its tree cover, according to Global Forest Watch. And deforestation isn’t slowing down. In just one week, from May 20-27, 2024, there were 127,301 deforestation alerts recorded in the state.
To determine how settlement, agriculture and deforestation affect the species, Brown and his team reviewed orchid bee surveys dating from September 1996 to September 1997. While the data were collected almost 30 years ago, they hadn’t been analyzed until now. “It’s incredibly gratifying to finally see this work come to light. That’s the great thing about science. If data is collected well, documented well, and analyzed well, it never expires,” Brown said.
Rather than count the orchid bees in one fragment of land over a long period of time, like most related studies, they collected bees from 130 sites around Rondônia. Their haul of more than 2,000 bees, across 48 species, included specimens from two new, still unnamed species, and four species previously unrecorded in Rondônia: Eufriesea violascens, Euglossa decorata, Euglossa ioprosopa and Euglossa viridis.
When comparing conserved land to settled areas that were disturbed before and after 1981, the researchers found the most orchid bees and highest species diversity in conserved land units. Areas settled more recently, since 1981, were intermediate in terms of bee abundance and diversity, while older settlements, those settled before 1981, had the lowest values for both.
“If we were in a conservation unit, we would find 3.4 more species than if we were in an older settlement, and 1.9 more species in newer settlements [compared to older settlements],” Brown said. “Those numbers give you a sense of how much the number of species drops when you go from fully forested areas to areas that have been settled and deforested.”
Because orchid bees need many different types of plants for foraging, nesting and mating, they’re considered an indicator species for environmental conditions. The findings suggest that whether an area was settled for cattle and agriculture 10 years ago or 30, orchid bees may not be able to find the resources they need.
Without healthy pollinators, the agricultural economy collapses alongside the wild ecosystems. “If we’re losing these bees, chances are we’re losing a lot of other species,” Brown said.
Breno Freitas, a zoologist at the Federal University of Ceará, who wasn’t involved in the study, said the results aren’t surprising.
“Most research is conducted in fragmented areas because it is expensive, time-consuming, and difficult to access these forested areas in the Amazon. But what’s different about this paper is that they didn’t work with one or two samples, they worked with a lot of different sites with many different situations. This kind of data is much more likely than fragment research to represent reality. It would be great if we could have more works like this,” Freitas said.
While the count isn’t recent, Daniel Souto Vilaros, a postdoctoral biologist at Utah State University who wasn’t involved in the study, said it still provides an important baseline for biodiversity in the region that could be compared to the current state of orchid bees as deforestation and the spread of agriculture continue.
“If they replicated the study now, the age of the data would actually be an advantage. They could try to find areas that have been disturbed more recently. I think it would be cool to replicate it in time and see if the result holds. I think that would be the next thing to do,” Souto Vilaros said.
Taxonomist Marcio Luiz Oliveira from the National Institute of Amazonian Research in Brazil, who was responsible for identifying the species of each bee collected for the study, said he hopes to continue working with orchid bees in the Brazilian Amazon because there are so many areas still targeted for land development. “We would like to study bees in these areas before the devastation,” Luiz Oliveira said.
Brown and his colleagues said they hope these results will inspire other researchers to try different methods of measuring biodiversity. “You don’t have to stay in one forest fragment for a whole year, you can go over many different areas for a shorter period of time and learn so much more about the population,” Brown said.
Research into orchid bees and stingless bees, Brazil’s other group of native bee species, continues to paint a broader and more detailed picture of the Amazon’s native pollinators.
“Regular monitoring of these populations could help us see more clearly the impacts of destruction on the biodiversity we rely on for our own survival, and work with stakeholders to ensure these and other pollinators remain part of our lives,” Brown said.
He added that while he’s not aware of any successful reversals of orchid bee species decline, it’s essential to slow deforestation and habitat fragmentation so that the resources that orchid bees need for nesting and feeding can support existing and future populations and allow continued gene flow. For orchid bees, that includes the maintenance of flowers for perfume collection for mating.
“It sounds sappy, but pollinators are key to our human survival,” Brown said. “With such a beautiful bee, we can get people interested in learning more, because pollinators are so important in helping people realize that they are connected to all that’s around them.”
Citation:
Brown, J. C., Corrêa-Neto, J. D., Ribeiro, C. F., & Oliveira, M. L. (2024). The impact of agricultural colonization and deforestation on orchid bees (Apidae: Euglossini) in the Brazilian Amazon. Biological Conservation, 293, 110560. doi:10.1016/j.biocon.2024.110560
Banner image: An orchid bee. Image via Wikimedia Commons.
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