Bees and other important insects may be spared thanks to a new discovery that could refine pesticides to only targets specific pests.
A team from Michigan State University has found the protein that with a few molecular tweaks could be used in pesticides to ensure they only eliminate necessary targets and not beneficial insects like bees.
Pyrethroids pesticides target the voltage-gated sodium channel–a protein found in nerve and muscle cells used for rapid electrical signaling. They bind to the voltage gate of the sodium channel and prevent it from closing.
The researchers focused on a single protein that could afford bumble bees the same resistance as humans – tau-fluvalinate, a pyrethroid insecticide.
“For the first time we are showing that unique structural features in bee sodium channels interfere with the binding of tau-fluvalinate to bumble bee sodium channels,” Ke Dong, MSU insect toxicologist and neurobiologist and co-author of the paper, said in a statement. “This opens the possibility of designing new chemicals that target sodium channels of pests but spare bees.”
Sodium channels are large transmembrane proteins of more than 2,000 amino acid residues. The researchers initially focused on sodium channels in several insects including mosquitoes, fruit flies, mites, roaches, and ticks.
“By examining wild mosquitoes that have become resistant to pyrethroids, we were able to help narrow down the potential sites on which to focus,” Dong said.
The researchers previously identified mutations that made the channels more resistant to pyrethroids and were able to identify two distinct pyrethroid binding sites on insect sodium channels. They also uncovered the molecular differences between mammals’ and insects’ differing reactions to pyrethroids.
In the new study, they focused on honey bees and bumble bees, both of which are highly sensitive to most pyrethroids, but were resistant to tau-fluvalinate.
The team discovered that the channel is resistant to tau-fluvalinate but sensitive to other pyrethroids and further mutational analysis and computer modeling showed that specific amino acid residues in bumble bee sodium channels are responsible for the selective toxicity.
The researchers now plan on examining sodium channels from various pest and beneficial insects to explore the features of pyrethroid binding sites, which could lay the groundwork for designing new and selective pesticides.
