A spore-producing bacterium is the source of various crystal toxins (known as Cry proteins) that are widely used in modern agriculture to combat insect pests – generally caterpillars and other larvae – that attack important crops. Pest control in corn, soybean, and cotton use these insecticidal proteins for protection against major insect pests. The pesticides are obtained from Bacillus thringiensis (Bt) bacteria to produce the proteins.
Bt Cry proteins are secreted by the bacteria but are harmless to the bacteria. They are harmless until ingested by insects and are then activated by the alkaline environment in the gut of insects which is entirely different from the acidic environment of our own digestive systems. In the insect’s gut, the proteins become a powerful feeding inhibitor by breaking down the insect’s gut lining. Bt Cry proteins are considered safe for humans.
Researchers continue to seek alternative solutions because there are concerns that insect pests could develop resistance to these toxic proteins.
Researchers from two Australian universities have analyzed the structure of a novel insecticidal protein that could be effective in protecting essential crops. The protein is naturally produced by ferns including common houseplants like brake ferns.
The newly discovered proteins offer a different mode of action from the Cry proteins and therefore are a potential solution to the problem of pest resistance to existing insecticides. The new family of insecticidal proteins is designated as iPD113 and has been shown to be very effective against caterpillar pests of corn and soybeans.
Photo, posted October 5, 2015, courtesy of Marianne Serra via Flickr.