(Beyond Pesticides, June 11, 2009) Massachusetts Institute of Technology (MIT) researchers and collaborators from Northeastern University have discovered a novel way to make pest insects more susceptible to bacterial and fungal infections by blocking part of the immune defenses. The new technique could offer a more sustainable way to protect crops and buildings from damage by termites and other pest insects. The study, “Targeting an antimicrobial effector function in insect immunity as a pest control strategy,” published in this weeks Proceedings of the National Academy of Sciences, finds that a sugar called GDL (glucono delta-lactone), a naturally occurring derivative of glucose, disables the specific proteins that insects embed in their nests and makes the insects more vulnerable to infection. GDL, commonly used as a food preservative, is biodegradable and inexpensive, making it an attractive alternative to chemical pesticides.
The researchers, including senior author MIT Professor Ram Sasisekharan, Ph.D., found that the proteins, known as gram-negative bacteria binding proteins (GNBPs), act as a first line of defense against pathogenic bacteria and fungus. Once the researchers discovered this function, they decided to try inhibiting the proteins, with an eye toward new methods of pest control.
The researchers gauged the effectiveness of GDL in laboratory tests using termites. A few days after being exposed to GDL, all of the insects died from opportunistic pathogenic infections. A control group of termites not exposed to GDL lived twice as long. Since this defense mechanism is only employed by certain insect species such as termites, locusts and cockroaches, GDL is harmless to beneficial insects such as ants, as well as other animals and plants, according to the researchers. The same cannot be said for chemical pesticides now commonly used.
“When you look at the chemical pesticides now used, they’re harmful not only for insects but also for humans too,” said Dr. Sasisekharan, who is the Edward Hood Taplin Professor and director of the Harvard-MIT Division of Health Sciences and Technology (HST).
According to Dr. Sasisekharan, “The GDL compound could be incorporated into building materials or paint to protect buildings from termites, or could be made into a spray for use in fields where pests need to be controlled. It could also be used in food processing and storage facilities. This research also lays the groundwork for possible development of similar agents to target pest insects.”
“Dr. Sasisekharan’s basic studies on innate immunity in insects have enabled him to devise a strategy to defeat them,” said Pamela Marino of the National Institutes of Health’s National Institute of General Medical Sciences, which partially supported the work. “The findings may lead to the development of new pesticides that pose a far lesser threat to human health than the chemical pesticides commonly used now.”
See Beyond Pesticides’ non- and least-toxic pest control methods fact sheets for more information on alternatives to chemical pesticides.