Caretakers versus Exploiters: Impacting Biodiversity in the Age of Humans

Why Should We Care?

It is important to realize how much of a role bats in North America play in insect control.  This is difficult to estimate or place a value on, but current estimates are at about $23 billion annually in the United States alone.¹⁵  Thomas Kunz, a renowned bat researcher at Boston University, calculated how more farmers in different regions would spend on pesticides if bats were not present. The value varied per each region in various studies.  One such study occurred in the Winter Garden agricultural region in southern Texas. The researchers estimated that at least 1.5 million bats feed nightly over the agricultural fields each summer night and the researchers calculated that the annual value of insect suppression by bats in the region approached $1.7 million. What they discovered was that the consumption of moths by Brazilian free-tailed bats reduces crop damage, eliminates one application of pesticide, and possibly delays the time when pesticides are first used. Each of these findings has important positive economic and environmental benefits.¹⁶

In addition to insect control for agricultural purposes, bats also reduce the insects responsible for the transmission of some infectious diseases.  According to the CDC, “West Nile virus is the most common virus spread by mosquitoes in the continental United States. People can also get sick from less common viruses spread by mosquitoes, like La Crosse encephalitis or St. Louis encephalitis. In rare cases, these can cause severe disease or even be deadly. Most people infected with these viruses do not have symptoms, or have only mild symptoms like fever, headache, nausea, and vomiting.”¹⁷ Other mosquito-borne illnesses include viruses like dengue, Zika, and chikungunya and are well-known to people living in US territories like Puerto Rico and the US Virgin Islands. Many people infected with these viruses can have symptoms that include fever, headache, rash, muscle pain, and joint pain.¹⁸ Zika virus can also affect the development of unborn children, causing a birth defect called microcephaly, a condition where a baby’s head is much smaller than expected because a baby’s brain has not developed properly during pregnancy or has stopped growing after birth.¹⁹