A Guide to Supporting Bats — Overlooked and Valuable to Agriculture
The common public perception of bats is historically negative. They are thought of as vectors of disease, aggressive towards humans, and often connotated with myths of vampires. However, bats are an integral and often overlooked component of the food system. Most people don’t know that bats act as pollinators as well as provide natural pest management, reducing the need for toxic pesticides. The diets of most microbats, which are mere inches in size and comprise 17 percent of the mammals on Earth , are composed of insects that eat developing fruit in orchards and cause significant harvest loss. However, despite these important roles, bat populations are increasingly disappearing due to encroachment of habitat, wind turbines, and diseases such as white-nose syndrome.
Economic analysis has shown that bats play a huge role in the agricultural economy. The disappearance of bats in North America could cause estimated economic losses of more than $3.7 billion dollars per year. The value of bats in agriculture is estimated to range from $3.7 billion per year to $53 billion per year. This is largely due to bats' ability to lessen reliance on pesticides, as well as their role in the pollination of many crops.
Bats are primary providers of natural pest management in agriculture. Bats eat bollworms, mosquitoes, and larvae that are harmful to many commercial crops. Studies have demonstrated that bats create ecosystem pressure on corn earworms, an insect that poses a significant risk to sweet corn production in the United States. Bats are natural predators to corn earworms and can significantly decrease the population of larvae that feed on corn crops. Corn earworms are becoming increasingly resistant to synthetic pesticides, making the role of bats in our food system even more important.
Bats also play a significant role in the pollination of many agricultural commodities. Most notably, the role of lesser long-nosed bats and tequila production. Mexican long-nosed bat and the lesser long-nosed bat are the primary pollinators of the agave plant, however, increasing demand for tequila has resulted in some farmers relying on cloning, a process of harvesting the hijuelos (baby plants) that are clones of the mother plant resulting in plants with the same genetic code. This decreases biodiversity and increases vulnerability to disease thus requiring greater use of insecticides. These insecticides are often toxic to bats, resulting in the deaths of the bats that feed on the chemically treated agave plants.
In California, many species of endangered bats serve as both pest controllers and pollinators. The Brazilian free-tailed bat primarily consumes moths, flying ants, weevils, and ground beetles. The moths consumed by the bats produce larvae responsible for the damage of crops, making the Brazilian free-tailed bat incredibly beneficial to farmers. However, their population is rapidly declining due to human disturbance, habitat destruction, and pesticide poisoning. The California Myotis bat eats moths, mosquitoes, and beetles and is currently under threat due to habitat destruction. The Yuma Myotis bat consumes small beetles, moths, flies, and termites, however, they are increasingly vulnerable due to pest control.
As important as they are to agriculture, bats are dying at increasing rates. White Nose Syndrome (WNS) is a disease responsible for the dramatic decline in bat populations throughout North America. Caused by a fungus that grows in damp dark conditions, WNS infects hibernating bats making them more active than usual thus depleting their conserved energy and limiting their ability to survive during the winter. WNS has already resulted in the deaths of millions of bats in North America including in northern California near Lassen Volcanic National Park. WNS is exacerbated by the disappearance of bat habitats due to human encroachment and cave closures, forcing bats into smaller and smaller areas amplifying the spread of the disease. The disease has spread quickly throughout the country from its first discovery in Albany, New York. Efforts to create habitats for bats are essential to the protection of species necessary for the agricultural industry.
Around the globe, farmers are beginning to adopt bat-friendly initiatives to limit the spread of infectious disease, habitat loss, and deaths from toxic agrochemicals. At the Herdade do Esporão Vineyard in Portugal, a bat conservation program has been initiated. According to Mário Carmo, the biologist in charge of the program, before 2011 no bats were living on the vineyard due to lack of shelter. To combat this, the vineyard installed 20 wooden bat boxes which are now inhabited by several native bat species. Rice farms in Northwestern Italy utilize bats to manage pests and reduce pesticide use through the YES!BAT program, which uses integrated pest management, a form of pest management that relies on natural processes rather than toxic pesticides. The program introduces bat houses into rice fields to provide adequate habitats for bat species that eat nocturnal insects that damage rice crops.
Aside from agricultural programs, individuals can also aid in the protection of bat habitats. According to Merlin Tuttle, a chiropterologist and founder of Merlin Tuttle’s Bat Conservation, installing bat boxes can provide much-needed habitats for endangered and threatened bat species. Bat houses can be mounted to outer exterior walls of buildings or homes and can provide secure shelter for hundreds of bats. Bat houses can be built inexpensively using plywood, or purchased by Bat Conservation International certified companies including California Houses for Bats and Napa Valley PSI. Merlin Tuttle offers a guide to selecting quality bat houses including ideal sizes, features, and locations.
Increasing threats against bats have widespread consequences. The value of bats to the agricultural industry are often overlooked, however they are responsible for extensive pest management and pollination. In order to protect bats, farmers and individuals can make efforts to restore habitats, limit the use of toxic pesticides and advocate for their protection.
