Question: What Is the World's Most Venomous Insect?
The most venomous insect isn't some rare, exotic rain forest creature. You may have them in your own yard. Can you name guess what it is?
Answer: The world's most venomous insect is an ant. Not the ant in the photo... those are fire ants, which are poisonous, but don't get the award for 'most venomous insect'. That prize goes to the harvester ant (Pogonomyrmex maricopa). The LD50 for harvester ant venom (in rodents) is 0.12 mg/kg. Compare that to a LD50 of 2.8 mg/kg for a honey bee (Apis mellifera) sting. Now... that's interesting, but the part I liked was that the researchers say that is "equivalent to 12 stings killing a 2 kg (4.4 lb) rat" (University of Florida Book of Insect Records). You have to wonder about that. Did they run out of lab animals and use some wharf rat in the research? Why not just say it takes about 3 stings to kill a one pound rat?
Insect venoms are comprised of amino acids, peptides and proteins. They may include alkaloids, terpenes, polysaccharides, biogenic amines (e.g., histamine), and organic acids (e.g., formic acid). Venoms also may contain allergenic proteins, which can trigger a potentially lethal immune response in sensitive individuals.
Biting and stinging are separate actions in ants. Some ants bite and do not sting. Some bite and spray venom on the bitten area. Some bite and inject formic acid with a stinger. Harvester and fire ants bite and sting in a two-part process. The ants will grab hold with their mandibles, and then pivot around, repeatedly stinging and injecting venom. The venom includes an alkaloid poison. Fire ant venom includes an alarm pheromone which chemically alerts other ants in the vicinity. Chemical signalling is why the ants all appear to sting at once... that is essentially what they do.