Economic value of the pest control service provided by Brazilian free-tailed bats in south-central Texas

www.frontiersinecology.org © The Ecological Society of America T the world, humans compete with a multitude of pest species for food, fiber, and timber, although natural predators greatly reduce the densities of many of these pests. Loss of natural pest control services could have important economic, environmental, and human health consequences (Daily 1997). The Brazilian free-tailed bat (Tadarida brasiliensis; Figure 1) provides a continental-scale, natural pest control service in North America. This species overwinters in south and central Mexico and migrates north each spring to form large breeding colonies in northern Mexico and the southwestern United States (Davis et al. 1962). Historic records of some summer cave colonies of this species reportedly exceed 20 million individuals. Over 100 million bats may disperse nightly from caves and bridges in south-central Texas to feed. These bats consume enormous quantities of insects throughout the warm months; lactating females, in particular, may ingest up to twothirds of their body mass each night (Kunz et al. 1995). The prey of these bats includes adults of several Lepidopteran species in the family Noctuidae (Lee and McCracken 2002, 2005), whose larvae are known agricultural pests, such as fall armyworm (Spodoptera frugiperda), cabbage looper (Trichoplusia ni), tobacco budworm (Heliothis virescens), and corn earworm or cotton bollworm (Helicoverpa zea). The cotton bollworm is among the most destructive agricultural pests in the Americas. Here we evaluate the magnitude of this previously unaccounted pest control service in cotton.