A team from the Technical University of Munich (TUM) has developed a biodegradable agent that keeps pests at bay without poisoning them. Like mosquito repellent used by bathers in the summer, biotechnologically produced cembratrienol deters voracious insects. If aphids have the choice between wheat seedlings with (right) and without CBT-ol treatment (left), they avoid the treated seedlings. Source: Wolfgang Mischko / TUM

With summer right around the corner and warmer days on the way, people want to spend time outside — from BBQs to gardening to lying on a hammock in the backyard.

But with warm weather comes pests. Insects can be annoying, but they can also destroy lawns and plants. One easy route to getting rid of pests is synthetic insecticides. While the insecticides get rid of pests, they are horrible for the environment. Luckily, a research team from the Technical University of Munich (TUM) has developed a biodegradable agent that keeps pests away without poisoning them or harming the environment.

Traditional synthetic insecticides are dangerous to bees, beetles, butterflies and grasshoppers because they are poisoning them and their environment. These insecticides affect the biodiversity of the environment, including the soils, lakes, rivers, seas, pretty much wherever insects live. Keeping these insects alive is important not only to their species livelihood but ours as well.

"It's not just about the bees, it's about the survival of humanity," says Professor Thomas Brück, who heads the Werner Siemens Chair of Synthetic Biotechnology at TU Munich. "Without the bees that pollinate a wide variety of plants, not only would our supermarket shelves be quite bare, but within a short time, it would no longer be possible to supply the world's population with food."

The new insecticide is biodegradable and virtually harmless to the environment. The plant spray keeps insects away just by a smell that is unpleasant to them.

"With our approach, we are opening the door to a fundamental change in crop protection," says Brück. "Instead of spraying poison, which inevitably also endangers useful species, we deliberately merely aggravate the pests."

The researchers took inspiration from the tobacco plant to create the new insecticide. Tobacco plants use the chemical cembratrienol (CBTol) to ward off pests using the chemical’s unpleasant smell. The research team uses synthetic biotechnology to isolate the parts of the tobacco plant genome that produces the CBTol. These parts were then built into the genome of E. coli bacteria. The bacteria were then fed grain-mill byproducts, fermenting the fodder in CBTol.

The biggest problem researchers ran into while developing the biodegradable insecticide was separating the active ingredients from the nutrient solution in the tobacco plant. The team uses centrifugal separation technology to achieve the separation. This technology uses a highly efficient process that works on an industrial scale. It was the first time that it was used to separate products of a fermentation process.

Pest control isn’t the only use for the CBTol spray. The spray could also be used as an antibacterial spray against gram-positive bacteria like MRSA and pneumonia.

The paper on the biodegradable insecticide was published in Green Chemistry.