How spider toxin can protect crops from insects

In a discovery that offers new ways to protect crops from insects, researchers have found that insecticides can be designed to target specific pests without harming beneficial species like bees.

And the answer lies in a potent spider toxin.

"Most insecticides used today take a carpet-bombing approach, killing indiscriminately and sometimes even hurting humans and other animals. The more specific a toxin's target, the less dangerous it is for everything else," explained Frank Bosmans, an assistant professor of physiology at the Johns Hopkins University's School of Medicine.

The finding began with the mistaken inclusion of a protein called Dc1a in a shipment sent by the team's Australian collaborators.

The protein was extracted from the venom of the desert bush spider Diguetia canities which lives in the deserts of the southwestern US and Mexico and is harmless to humans.

In lab experiments on cockroaches, they used spider toxins to study the proteins that let nerve cells send out electrical signals.

First, Bosmans and his team inserted the protein's gene into cockroaches.

They then used electrodes to monitor the flow of sodium into the cells.

"Adding spider toxins that interfere with the function of the sodium channels shed light on the channels' activity, since different toxins inhibit different parts of the protein, causing different effects," Bosmans said.

The findings suggest that naturally occurring insect toxins can be lethal for one species and harmless for a closely related one.

The team's next step is to test the toxin on other insect species to determine its full range, said the study appeared in the journal Nature Communications.