An overview of contaminants and bats, with special reference to insecticides and the Indiana bat


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January 2002


Bats accumulate and suffer from adverse effects of environmental contaminants, and this raises concern about potential impacts on endangered species, such as the Indiana bat (Myotis sodalis). Organochlorine insecticides are persistent, lipophilic neurotoxins that have been implicated as agents of mortality in populations of other species of bat, including gray bats (Myotis grisescens) in Missouri. We provide previously unpublished data, obtained in 1975-] 978, on organochlorines in carcasses and brains of 3 8 Indiana bats and guano from five roosts. These data provide the first evidence for mortality of Indiana bats due to insecticides of the organochlorine pesticide era and provide a benchmark for future studies. Most organochlorines have been eliminated from use in the United States, but they are stil1 found in decreasing amounts in bats and continue to be elevated at "hotspots" of contaminati on. Organophosphate, carbamate, and pyrethroid insecticides are used most widely in place of organochlorines, but their occurrence and effects in bats are poorly known. Three studies suggest inhibition of cholinesterase in brains of bats caused by exposure to organophosphates or carbamates. Pyrethroid insecticides recently were detected in tissues or guano of some bats, including species of Myotis in Missouri. We compare data on insecticide use and agricultural production from counties with records of reproductively active females or juveniles in Missouri and Indiana, searching for differences associated with declines in populations ofIndiana bats at hibernacula in Missouri but not in Indiana. Intensity ofagricultural production, types of crops requiring insecticides, and general insecticide use and intensity were higher in Indiana. However, pyrethroid insecticides were used more in Missouri. Use of insecticides in southeastern Missouri is very intensive because of applications to cotton, and this area should be investigated for use by Indiana bats and their possible exposure to insecticides.


Bat, Bats, Indiana Bat, Contaminants And Bats, Insecticides And The Indiana Bat

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