Say, in a perfect world situation, the weevils eat every bit of the salvinia, then what? Do the weevils die off? Or do they figure out a way to adapt to eat on beneficial plants? Former cotton farmer here. Weevil is a 4-letter word in the agricultural world.
Insects such as the salvinia weevil, which have been approved by the USDA for use as biological controls, have gone through extensive testing to ensure that they will not consume other native plants due to these very concerns. They will only consume the salvinia. While it is unlikely that the weevils would be effective enough to consume all of the salvinia, and therefore they’re just one tool in our Integrated Pest Management toolbox, without salvinia to eat they would not be able to survive and would not consume other plant species.
