German researchers have extracted an insect repellent from tobacco plants that might scare away pests, such as aphids.
It also acts as an antibacterial agent, they report in a scientific paper.
The insect repellent they have developed is biodegradable and ecologically harmless.
It works much like mosquito repellents, they say.
"With our approach, we are opening the door to a fundamental change in crop protection," said Professor Thomas Brück of the Technical University of Munich.
"Instead of spraying poison, which inevitably also endangers useful species (such as bees), we deliberately merely aggravate the pests," he said.
The researchers extracted the gene responsible for producing cembratrienol in tobacco leaves, moved it to bacteria which they could then multiply in fermentation tanks, using a process similar to producing insulin.
"The key challenge during production was to separate the active ingredients from the nutrient solution at the end of the process," explains Mirjana Minceva, Professor of Biothermodynamics at the TUM Weihenstephan Campus.
The solution was centrifugal separation chromatography: a highly efficient process that works equally well on an industrial scale, but hitherto had never been used to separate products from fermentation processes.
Initial investigations indicate that the CBTol spray is non-toxic to insects, yet still protects against aphids. Since it is biodegradable, it does not accumulate.
In addition, the bioactivity tests showed that cembratrienol has an antibacterial effect on gram-positive bacteria.
It can thus be used as a disinfectant spray that acts specifically against pathogens such as Staphylococcus aureus (MRSA pathogen), Streptococcus pneumoniae (pneumonia pathogen) or Listeria monocytogenes (listeriosis pathogen).