Researchers at the University of Warwick have discovered how a protein from a bacterium acts like a cunningly-designed poison pill box that could be used to design a range of natural insecticides.
It has long been known that nematode worms can infect and kill insect pests with the help of a bacterium which they harbour inside their intestine. The bacterium uses a toxic protein (XptA1) which helps the nematode to kill and feed on the dead body of the insect. The toxin not only kills the target insect, but also prevents other predators from eating the body, thus giving free reign to the nematode worms to consume it, multiply and move on. However, until now researchers had little idea of the make-up of XptA1 and therefore how it worked.
The XptA1 protein seemed to specifically target Pieris Brassicae ‘cabbage-white’ caterpillars. Researchers discovered that, while XptA1 was highly selective, in that it bound to the cabbage-white butterfly caterpillar, there were variants of this family of toxic proteins (such as XptA2) that targeted other insects.
“This research gives us crucial new insights into a family of naturally occurring proteins that are toxic to a number of insect pests,” said Dr Sarah Lee from the University of Warwick.” They offer an alternative to current commercial protein based insect toxins have been in use for 40 years and are now starting to meet some resistance. This potential new family of protein based insecticides would overcome such resistance as they operate in an entirely different way."