Metarhizium brunneum and Beauveria bassiana are naturally occurring fungi that have been adapted by livestock and plant scientists into pesticides that specifically target house flies and stable flies. Dr. Erika Machtinger and colleagues from the University of Florida are the first to show that the fungi reduce the number of eggs that become flies.
Commercially available versions of Metarhizium brunneum and Beauveria bassiana have been available for 15 years and have been primarily used to reduce fly populations in livestock, poultry, and plants by applying the fungi to the sites where flies exist. The fungi interfere with the ability of flies to reproduce. The new study shows that the fungi also prevent fly eggs from maturing.
Metarhizium brunneum was found to be the most effective natural fly killer. The fungus killed over 50 percent of fly larvae before the larvae hatched. The purpose of the investigation was to determine which fungus worked best in preventing flies from pestering animals that are food for humans and potentially infecting the animals with disease.
Only once case of adverse human reaction to Metarhizium brunneum is known. The fungus can cause a reduction in the human immune system and is a breathing hazard like other fungi for people who are allergic to fungi. The idea is not to kill all the house flies or other flies in the world. Flies perform important functions like disposing of dead animals and waste. The study does show that fungi can be used as effectively as chemical insecticides that are toxic.
