Beyond Bt: Using Microbial Pesticides
Bactur, Bactospeine, Bioworm, Dipel, Javelin, Topside – All names for a commonly used microbial pesticide, Bacillius thuringiensis (Bt). Bt has been used commercially since 1961, when it was first registered by the EPA. Today there are over 187 microbial pesticides on the market, and many are used successfully to control a variety of insects and diseases in landscape and agricultural settings. These materials are great alternative to synthetic, broad-based chemical pesticides.
Microbial pesticides are made from bacteria, fungi, protozoa, viruses, and other organisms (or their toxins) that cause death or disease of insects or plant pathogens. They are sold as dusts, wettable powders, sprays, granules, etc. and are applied in the same way as conventional pesticides.
The greatest advantage to using these products is that they are safe for the environment. They target a certain pest or pest group and are thus non-toxic to humans and other life not related to the target pest. For example, the microbial insecticides do not harm predatory and parasitic insects because the toxin that a given organism produces is harmless on its own, and only becomes activated when it encounters a specific "receptor site" on its host.
There are a few caveats to using microbials. Some require multiple applications, and correct timing of application is crucial. They also have a short shelf life, and must be protected from exposure to UV light and excessive heat. Most of the products that control insects must be ingested to be effective. And finally, some materials are costly due to their time-consuming production and difficulty in large-scale production.
Bacillius thuringiensis is the most common organism used in microbial products. Several strains have been discovered, each targeting the larvae of specific pests. One strain targets beetles, specifically Colorado potato beetle, elm leaf beetle, and cottonwood beetle. Another strain targets only mosquito, black fly, and fungus gnat larvae, but not house fly larvae. Research continues to identifying other strains. The table below lists several microbial products available to Utah growers and landscapers.
So why do synthetic pesticides still significantly outnumber bio-pesticides? One reason is the "caveats" listed above. More likely, the pest control industry has not heard a large enough demand from consumers. The need for a wider variety of organic and alternative pest control treatments will certainly drive the product development in the future.