The Non-Target Effects of Bti Spraying in Maryland

Abstract

Bti (Bacillus thuringiensis israelensis) is a naturally occurring bacteria that has been used as a biopesticide to successfully control fly groups that are vectors of serious human diseases primarily in tropical countries around the world. In Europe and the United States however, Bti has primarily been utilized to control nuisance fly species such as non-biting midges, blackflies, and mosquitos. Studies in France and Germany have shown significant non-target species and ecological impacts, which include negative impacts to populations of related Diptera (true flies) and insectivorous birds (Poulin et al., 2010; Poulin et al., 2016; Algeier et al., 2018). Despite relatively long-term use for approximately 30 years, scant ecological studies have been conducted in the United States regarding the non-target ecological effects of Bti spraying. In Maryland, Bti spraying was introduced in 2016 in Senate Bill 801, which started the Maryland Black Fly Pilot Program in the Potomac River. Despite having no scientific studies regarding the effects of long-term Bti usage, larger spray programs are being implemented in the state. Referring to the results of the many European studies, the language in Senate Bill 801 should be changed to require the implementation of proper studies documenting the long-term effects of the biopesticide and the language should be changed from “may” to “must” regarding items 2 through 6.