Even lizards could pose a threat. I've heard a fishy tale when a common house gecko bit into a fishes gill stuff. The end result was like removing 1 lung.
You'd better be turning over 4-5x an hour to get away with feeding live insects on a regular basis...feedings crickets or other live non-worm insects is like setting off a bug bomb in your tank...mayhem everywhere.
I feed my Oscars, jaguar, dempseys etc wasps all the times. The oscar sometimes jumps up to eat the wasps if it flies beneath the cover glas. That is no harm to the fish.
I have many times caught fish in the nature which have wasps in their belly so i guess that is a normal food for them.
with the Venom or posion, i am pretty sure that it has to get into the bloodstream of its victim to cause an effect. by going through the digestive sytem first, it will become neutralised and won't have an effect. that is my theory!!! (don't hold me to it). i am talkin about dead wasps and stuff tho, ones that don't struggle and wiggle and what have ya.