Andy Morffew. Short-tailed Fruit Bat. Flickr.com, taken on Jan 21, 2015.
Bats are agricultural treasures
Bats are the second most common mammalian species (after rodents). Many of us are not aware of the vital importance of bats in agricultural ecosystems (1, 2, 3).
Bats as exceptional pest controllers
For one thing, insect-eating bats are phenomenal at keeping pest populations under control (1, 2). Given that bats feed at night, they take care of many moth pests. For example, Mexican free-tailed bats eat a lot of corn earworm moths as well as other crop pests.
To get an idea of the far-reaching effect of bats on pest control, you only have to visit Bracken Cave, north of San Antonia, Texas. Bracken Cave houses the largest bat colony in the world: there are more than 15 million Mexican free-tailed bats in that cave. Amazingly, this batch of bats munches on almost 150 tons (~300,000 lbs) of those moths every night.
Fruit bats are more effective pollinators than birds
The common pollinators - birds, bees, butterflies - are usually diurnal, that is they are around during the day time. However, bats are up at night. In fact, bats are a significant pollinator of over 700 different types of plants.
Significantly, research suggests that bats are more effective pollinators than birds. Bats are particularly adept at pollinating plants (3). They carry large amounts of pollen on their fur and transfer a lot of grains of pollen per flower visit. Studies have shown that bats deposited 22 times more pollen than hummingbirds.
Moreover, bats can carry pollen over substantial distances. This is very helpful as bat pollination takes place in plants that live in low densities (3).
"Birds of the night": Fruit bats work the night shift
Most bats are active only at night. This is perfect for plants whose flowers open at night. Interestingly, certain flowers have adapted to attract the larger animal pollinators.
Thus, flowers that attract bats tend to be large, open late in the day or at night, are dull in color, and have a musty, sulfurous odor. Some flowers are so adept that they also cater to echolocating bats. Flowers that contain more nectar return more echoes back to the bats (3).
In addition to their pollination prowess, fruit bats are effective seed dispersers, particularly in tropical forests. In the same vein, bats play a role in improving the yield of mango orchards. Not only do fruit bats - like flying foxes - help with cross-pollination of the trees, they also disperse mango seed. Bat-processed mango seeds have higher rates of germination and fruit bats are strong enough to carry the larger fruit, dispersing the seed.
In India, bat conservation teams call bats "birds of the night" for their valuable role in agriculture.
Baby fruit bat sitting in a blanket munching on a banana, Courtesy of Dall-e 2, Jan 30, 2023
How did bats and bananas co-evolve?
This article highlights the co-evolution of bats and bananas over 50 million years. Wild banana trees have a characteristic large flower with an intense musty odor. The flower only opens at night and is high in nectar. This attracts fruit bats that help spread the pollen across the plants.
Bats also eat the wild fruit. This has large seeds that are too large for birds. The seeds are excreted with bat poop along the forest floor giving the seeds a fertilizer cover to jump start their growth.
Wild banana fruit would not be appetizing for us, as the fruit is mostly seeds with very little pulp. However, wild banana trees were valued for their large leaves which were used for ropes, nets, and wrappers for food. Thousands of years ago, villagers would transplant new stems from the wild banana trees ("suckers") that had more edible fruit to create locally grown plants.
Over time, those cultivated plants produced more edible fruit, However, commercially grown plants (from suckers) are either seedless or the seeds are sterile. And those genetically uniform domesticated plants are highly susceptible to fungal disease.
Thus, one needs the original wild banana trees to continue to provide suckers to generate new banana plants with edible fruit. Unfortunately, the bats and the wild banana trees are in decline.
If fruit bats disappeared from the world
This topic of bats and bananas is an odd one to include in posts about health.
However, when I was researching bats, I came up on several articles that highlighted the importance of bats in keeping certain plants alive. I wondered why those plants were so dependent on bats.
Thus, this article. It is curious how some species are adversarial and others create positive feedback loops in their evolution. Wild banana trees evolved to produce just the perfect blend of odor, taste, and amount of nectar to attract bats. If fruit bats disappeared from the world, so would bananas (and many other fruit).
References
- RamÃrez-Fráncel LA, GarcÃa-Herrera LV, Losada-Prado S, Reinoso-Flórez G, Sánchez-Hernández A, Estrada-Villegas S, Lim BK, Guevara G. Bats and their vital ecosystem services: a global review. Integr Zool. 2022 Jan;17(1):2-23. doi: 10.1111/1749-4877.12552. Epub 2021 Jun 8. PMID: 34003577.
- Aguiar LMS, Bueno-Rocha ID, Oliveira G, Pires ES, Vasconcelos S, Nunes GL, Frizzas MR, Togni PHB. Going out for dinner-The consumption of agriculture pests by bats in urban areas. PLoS One. 2021 Oct 21;16(10):e0258066. doi: 10.1371/journal.pone.0258066. PMID: 34673777; PMCID: PMC8530310.
- Fleming TH, Geiselman C, Kress WJ. The evolution of bat pollination: a phylogenetic perspective. Ann Bot. 2009 Nov;104(6):1017-43. doi: 10.1093/aob/mcp197. Epub 2009 Sep 29. PMID: 19789175; PMCID: PMC2766192.