Well I take it a lot of contact poisons doesn’t work on them very well. Like praying spectracide or whatever around a clean bed/sleeping area.
Freegards
It would seem to me that the most plausible method that could be invented to kill them with normal insecticides would be a trap that simulates their blood feed. This, they would dig into.
Maybe have one of those naked dogs and coat it in pyrethrin (if that is not toxic to the dog). Bedbugs go for dog. Bedbugs eat poison. Bedbugs die. But that poor dog!
Or could there be something the people could eat that would make their blood poisonous to the bugs?