A soil bacterium is revolutionizing agriculture by turning crops into their own pest killers.

Nature · Published 3 October 2026 Swipe more like this →

In short: Bacillus thuringiensis, a naturally occurring soil bacterium, produces proteins lethal to specific insect pests. By applying these as sprays or engineering them directly into crops, farmers can target harmful larvae while sparing pollinators and beneficial insects. It is a cornerstone of modern organic farming and genetically modified agriculture alike.

Discovered in 1901 by a Japanese scientist investigating silkworm decline, Bacillus thuringiensis (Bt) has become a primary tool for biological pest control. The bacterium produces crystal proteins, known as delta endotoxins, during sporulation. When susceptible insects like caterpillars, beetles, or fly larvae ingest these crystals, the proteins bind to receptors in their mid-gut, causing a rupture that leads to starvation and death. Because humans and other mammals lack the specific digestive enzymes and receptors required to activate these proteins, Bt is considered nontoxic to them.

The application of Bt has evolved significantly since it was first used commercially as a spray in the United States in 1958. Since 1995, when the U.S. Environmental Protection Agency first approved the technology, genetic engineering has allowed scientists to introduce Bt genes directly into crops like corn, cotton, and potatoes. This innovation has dramatically reduced the need for broad-spectrum chemical insecticides, which often kill both pests and beneficial insects. For instance, conventional pesticide use for the European corn borer dropped by approximately one-third following the introduction of Bt corn.

Despite its benefits, the widespread use of Bt faces challenges. Sunlight degrades spray formulations within a week, and some newer strains lose effectiveness in as little as 24 hours. More critically, the evolution of pest resistance threatens the long-term viability of Bt technology. To mitigate this, farmers often plant refuges—plots of non-Bt crops—to maintain populations of susceptible insects. Furthermore, research continues into the environmental impact of Bt, including how proteins accumulate in soil and the potential for gene flow to wild plant relatives, such as the 2003 study on wild sunflowers.

Bt is closely related to other bacteria in the Bacillus cereus group, including the pathogen that causes anthrax. The primary difference between these organisms often lies in their plasmids, which carry the genes for toxin production. While Bt is a powerful tool for integrated pest management, its future depends on careful risk management to ensure that pests do not render this environmentally benign solution ineffective.

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