ÌÇÐÄÊÓƵ

Climate change may separate wild vanilla plants from pollinators, risking future supply

Vanilla flavoring is widely used in food, pharmaceuticals, and cosmetics. The primary source, Vanilla planifolia, however, is vulnerable to diseases, drought, and heat—stressors expected to become more frequent under climate change. Wild Vanilla species offer a genetic reservoir of crop wild relatives ensuring the future of the vanilla crop. Scientists have now examined how climate change could cause mismatches in habitat overlap of wild vanilla and their pollinating insects.

"Climate change may lead to a reduced habitat overlap between Vanilla orchid species and their pollinators, resulting in plant-pollinator decoupling that negatively affects the survival of wild vanilla populations," said Dr. Charlotte Watteyn, a researcher at KU Leuven and Lankester Botanical Garden Research Center at University of Costa Rica (UVR) and first author of the Frontiers in Plant Science study.

"Conserving the natural populations of wild Vanilla species, and the huge genetic diversity they hold, is crucial to ensure the future of vanilla, a key tropical crop for the global food industry," added senior author Prof Bart Muys of KU Leuven.

Mismatched habitats

The team modeled the habitat distribution and overlap of 11 neotropical Vanilla species and seven previously observed pollinators under two climate change scenarios. The "middle of the road" scenario (SSP2.4-5) represents moderate challenges to both climate change mitigation and adaptation, and follows a pathway of balanced energy development, while the "rocky road" scenario (SSP3-7.0) is characterized by many challenges, relies heavily on fossil fuels, and there is less global cooperation to mitigate climate change.

They found that for seven Vanilla species, climate conditions could become more favorable by 2050 in both scenarios. These species could expand their habitats by up to 140%, while the area with suitable habitat for the other four species was predicted to shrink by up to 53%.

For pollinators, the future on a warming planet could be more dire. Habitat suitability of all pollinators was found likely to decline, with a slightly higher negative change under the SSP3-7.0 scenario. "Despite the possible increase in suitable habitat for some Vanilla species, their pollinator-dependency may imperil the survival of natural populations," Watteyn explained.

It is unclear if other pollinators can take the place of those that might disappear from wild vanilla habitats. "Vanilla species are known for their specialized relationships with pollinators, hence, they may experience difficulties in replacing pollinators," Watteyn said. "The future may look brighter for species that are not reliant on a single vector for pollination."

Most species, however, usually depend on just one or a few certain pollinators.

Robust crops needed

Maintaining wild vanilla plants is not only important for biodiversity but also for agriculture. The commercially used crop species is characterized by low genetic diversity, which can affect product yield, quality, and stability negatively, but agricultural resilience could be enhanced by diversifying crops.

"Wild Vanilla species have the potential to mitigate these problems as they continue to co-evolve in the wild, developing traits of interest for crop improvement, for example, drought and heat tolerance and pathogen resistance," explained Muys.

Many Vanilla species are already threatened, and natural pollination rarely occurs. Forest fragmentation, habitat loss, and extreme temperatures exacerbate an already dire scenario for the survival of the "queen of all flavors."

"Collaborative research on the ecology and genetic diversity of wild vanilla across its natural distribution is paramount if we want to take vanilla breeding into the future, by ethically and sustainably using the local variation to answer global needs," said co-author Prof Adam Karremans, the director of Lankester Botanical Garden Research Center at UCR.

The results, the authors cautioned, should be interpreted carefully as occurrence records for wild Vanilla species and pollinators are sparse. Habitat overlaps could shift when ecological interactions like seed dispersion and interactions with microorganisms, or disturbances like habitat conversion and illegal extraction are also included in the models.

"Like cacao and coffee, vanilla is a global export crop with high international market value. It's grown to make profit, and is a key driver for rural development, agricultural innovation, and overall welfare," Watteyn concluded. "Cultivation benefits smallholder farming communities across the tropics, so there is an urgent need to enhance the resilience of vanilla farming systems."