MIT researchers and collaborators from Northeastern University have discovered what could be a more sustainable way to protect crops and buildings from damage by termites and other pest insects, which is estimated to cost more than $30 billion per year. Their technique blocks part of the insects’ immune defenses, making the pests more susceptible to deadly bacterial and fungal infections.

Professor Ram Sasisekharan and his colleagues found that proteins embedded in insect nests, known as gram-negative-bacteria-binding proteins (GNBPs), act as a first line of defense against pathogenic bacteria and fungi. When the proteins encounter such pathogens, they chop them up and expose the parts to the insects, priming their immune response.

Seeking to exploit this discovery for pest control, the researchers discovered that a sugar called GDL (glucono delta-lactone), a naturally occurring derivative of glucose, can disable the proteins, making the insects more vulnerable to infection.

Since only certain insect species (such as termites, locusts, and cockroaches) employ GNBPs as an immune mechanism, GDL is harmless to beneficial insects such as ants. Nor does it affect other animals or plants. The same cannot be said for common chemical pesticides. “When you look at the chemical pesticides now used, they’re harmful not only for insects but also for humans, too,” says ­Sasisekharan, who directs the Harvard-MIT Division of Health Sciences and Technology.

GDL, commonly used as a food additive, is biodegradable and inexpensive, making it an attractive alternative to chemical pesticides. The compound could be incorporated into building materials or paint to protect buildings from termites. It could also be made into a spray for use in fields where pests need to be controlled.