Andrew M. Barton, Ph.D.
EXCERPT: “The need for public education about bats, including their positive and negative impacts, is urgent and vital to their conservation.” (Zhao 2020)
BATS AND COVID-19
The world is gripped by a struggle to reduce the impacts of COVID-19. Global initiatives are focusing on reducing disease transmission through social distancing and travel restrictions, bolstering health care systems, and developing new treatments and vaccines. Less prominent but equally important in the long run are efforts to better understand how the virus and other microbial pathogens are transmitted to humans. Conservationists are highly supportive of such initiatives, but are cautioning that the identification of wild reservoirs of diseases could lead to useless and indiscriminate harm to wild animals, particularly bats (Zhao 2020). In a paper in Nature in early February 2020, scientists concluded that the RNA of SARS-CoV-2, the virus causing COVID-19, was most similar to a coronavirus found in horseshoe bats (Rhinolophus affinis) sampled not far from Hubei province, where the disease first emerged (Andersen et al. 2020).
WHAT DO BATS DO?
Given the role of bats as reservoirs for disease-causing viruses such as SARS-CoV-2, we might wonder what other functions bats provide in ecosystems. In fact, they play extraordinarily important ecological roles: as predators of insects, prey for larger vertebrates, pollinators of plants, and dispersers of seeds. In a review of the importance of bats, Kasso and Balakrishnan (2013) estimate that bats consume at least 25% of their body weight in insects each night, with lactating females gobbling down more than their own weight. That can add up in large colonies (Figure 1). A colony of 30,000 southeastern bats (Myotis austroriparius) in Florida, for instance, consumed about 15 tons of mosquitoes per year.
These feeding habits translate into substantial economic benefits for humans. For example, Brazilian free-tail bats (Tadarida brasiliensis) live in enormous breeding colonies in Texas and northern Mexico, where they prey on the corn earworm and cotton bollworm, serious pests of those crops. The value of their predation has been pegged at more than $700,000 per year for the cotton crop alone in an 8-county region of south-central Texas (Cleveland et al. 2006).
Although bats cannot compete with birds as pollinators, they’ve been documented pollinating at least 528 plant species in 67 families worldwide. They are the major pollinator for columnar cacti and agaves in desert ecosystems where those two groups of species make up a large portion of the plant biomass (see Figure 2 below). They also play important roles as seed dispersers in tropical forests, especially in helping initiate forest regeneration after disturbance (Kasso and Balakrishnan 2013).
SETTING THE RECORD STRAIGHT ABOUT COVID-19 AND BATS
Disease strikes fear in people, which can lead to actions that appeal to a sense of security but do little to solve the underlying problem—sometimes even negatively impacting ecosystems and people alike. This has certainly been the case with COVID-19.
Residents of a town in northern Peru set out to destroy a local population of Myotis bats after hearing of their role in COVID-19. The bats were spared only by their quick relocation by the Peruvian National Forest and Wildlife Service (Gómez Durán 2020). Similarly, some people in Hubei province advocated for the elimination of bats because of their association with the virus (Zhou et al. 2020). This was despite the fact that horseshoe bats, the purported disease reservoir, generally roost and feed far from human habitations. Scientists and wildlife managers in Peru, China, and across the world are working hard to educate people about the benefits of bats and the uselessness of killing them in their native habitats as a method for staving off disease.
THE WILDLIFE TRADE AND THE ONE HEALTH PERSPECTIVE
Conservationists and infectious disease scientists have argued vehemently that the cause of diseases like COVID-19 that jump from wild animals to humans is NOT the wild populations themselves. Rather, it is the enormous market for parts of those animals, which are used for food and traditional medicines.
Accordingly, as shown in Figure 3, the solution to reducing the emergence of such zoonotic diseases is NOT eliminating wildlife but eliminating wildlife trafficking and live animal markets (Global Wildlife Conservation 2020; Kimbrough 2020).
A silver lining of the COVID-19 pandemic may be the creation of new laws that ban the wildlife trade, especially in Asia, where it is most common. China has already imposed a temporary ban on live wild animal markets. The acting executive secretary of the United Nations Convention on Biological Diversity, Elizabeth Maruma Mrema, has strongly advocated for a permanent global ban on such wildlife trade, as have other conservation leaders (Wildlife Conservation Society; Global Wildlife Conservation). Mrema remarked that “there were clear links between the destruction of nature and new human illnesses.” (Greenfield 2020).
An even larger perspective on human and ecological health has been called for as humans continue to alter Earth systems and new human diseases emerge. One of the most ambitious approaches is the
One Health Initiative, which “is a movement to forge co-equal, all-inclusive collaborations between physicians, osteopathic physicians, veterinarians, dentists, nurses and other scientific-health and environmentally related disciplines…” (Figure 4).
The goal of the initiative is “improving the lives of all species–human and animal” (One Health Initiative 2020). COVID-19 has revealed that better management of both public health and the environment are needed to make strides towards a true one-health approach—and that such progress is desperately needed (Jupiter 2020).
The COVID-19 pandemic has laid bare the intimate relationships between human disease and the environmental support systems of the Earth. This current disease afflicting humanity is just one in a long series of diseases that have emerged as a result of human invasion of forests and exploitation of wildlife populations. Legally restricting the trafficking of wild animals would be an important step in breaking one of the links of these pathways. A larger, comprehensive one-health perspective provides a blueprint for recognizing and acting on the inextricable connections between Earth systems and human well-being.
Andersen, K.G., A. Rambaut, W.I. Lipkin, et al. 2020. The proximal origin of SARS-CoV-2. Nature Medicine. https://doi.org/10.1038/s41591-020-0820-9.
Global Wildlife Conservation. 2020. “Coronaviruses and the human meat market.” https://www.globalwildlife.org/blog/coronaviruses-and-the-human-meat-market/ [Accessed 11 April 2020]
Greenfield, P. 2020. Ban wildlife markets to avert pandemics, says UN biodiversity chief. The Guardian, 6 March 2020. https://www.theguardian.com/world/2020/apr/06/ban-live-animal-markets-pandemics-un-biodiversity-chief-age-of-extinction [Accessed 11 April 2020]
Jupiter, S. 2020. Better environmental management required for One Health. Medium, 7 April 2020. https://medium.com/@WCS/better-environmental-management-required-for-one-health-ee404467911 [Accessed 11 April 2020]
One Health Initiative. http://www.onehealthinitiative.com [Accessed 11 April 2020]