Research on a biopesticide derived from a strain of naturally occurring soil fungus has confirmed the material’s effectiveness at suppressing the most common variety of tick that spreads Lyme disease. Researchers from the Connecticut Agricultural Experiment Station demonstrated a significant reduction in the number of blacklegged, or “deer” ticks, up to five weeks after the material’s application. The biopesticide’s active ingredient, which has been registered with the U.S. Environmental Protection Agency (EPA), is derived from the fungus Metarhizium anisopliae. The researchers used two applications of the biopesticide approximately seven weeks apart and at two rates before measuring for blacklegged ticks. There was no significant difference in the number of tick nymphs after the first application compared to the control but both treatment rates showed significantly fewer nymphs both three and five weeks after the second application. During the third week after the second application, 87.1 and 96.1 percent fewer ticks were collected from lower and higher rate-treated sites, respectively, and after the fifth week, tick reductions were 53.2 and 73.8 percent, respectively.
Data submitted as part of the registration process also indicates that the biopesticide is less toxic to humans and many non-target organisms than other products currently use to prevent the transmission of Lyme disease. These pesticides include DEET applied as a topical repellent and synthetic pyrethroids including permethrin and bifenthrin which are sprayed in outdoor settings to kill disease-bearing ticks. For years scientists have raised concerns about the use of DEET and seizures among children, even though the EPA says that there is not enough information to implicate DEET with these incidents. DEET is quickly absorbed through the skin and has caused adverse effects including severe skin reactions such as large blisters and burning sensations. Use of DEET by pregnant woman has been linked to birth defects, and laboratory studies have found that DEET can cause neurological damage, including brain damage in children. EPA classifies permethrin as a possible human carcinogen, based on evidence of lung tumors in lab animals exposed to the chemical and also lists it as a suspected endocrine disruptor. In addition to these human health effects, pyrethroids are persistent in the environment and adversely impact non-target organisms.
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