I wonder why they haven't started using the stuff that rodents don't like. Underground cables have used it for a while now. Maybe cause they can't make it in the cross linked high temp version for engine bays?
We've had several vehicle repairs due to rodents. Squirrels are the worst. Thankfully the bike has not been 'eaten' yet, although it would be easier to fix than some of the wires they have gotten to on the truck.