Laser resistance can take a lot of forms. In the case of weeds, I’d bet that cat briers are already effectively laser proof. You can burn them down, but they send off shoots and store up massive amounts of energy in fragmented little potatoes. Miss any of them, and they come back up and keep going.

So that’s one solution, and it’s a big space for biology to play in. The bigger question will probably be whether or not there’s a route where weeds can make incremental progress toward better resistance from where they are right now.

For insects, as someone else pointed out, the easiest route is probably mimicry. But we might also see insects capable of recognizing the laser bots, noticing the chemical signals of burning bugs, etc.