While some pheromones are known to attract species for reproductive purposes, these particular pheromones act more as a repellent, Benoit explained.
"These pheromones also can be bought from any chemical company. They're well-established chemicals, are easy to make in the lab, and are readily available," he said.
Two types of desiccant dusts were used in the experiments: diatomaceous earth, a naturally occurring, chalky substance, and a compound called Dri-die, made from a silica gel. Desiccant dusts are designed to disturb the bed bugs' cuticle, particularly the waxy outer layer on insects that allows bugs to stay hydrated. Without the waxy protection, insects are more prone to dry up and die.
The researchers first tested the chemical combination on five bed bugs at a time for 10-minute exposures in petri dishes. They tested both types of desiccant dusts as well as each pheromone component alone and in a blend more typical of natural secretion.
Bed bugs exposed to Dri-die and a blend of pheromones lost water at a much faster rate than did bed bugs treated with the desiccant dust alone. The scientists found that bed bugs exposed to Dri-die alone lost 21 percent more water than untreated control bugs. Water loss nearly doubled with either (E)-2-hexenal or (E)-2-octenal applied alone and tripled with a blend of both pheromones.
Young bed bugs exposed to the combination died in about a day, three days earlier than control bed bugs. Adult female bed bugs exposed to the combination survived for about 6 days, compared to females exposed only to the desiccant dust, which lived for an average of 17 days.
In petri dish tests, the scientists found that the combined treatments using Dri-die consistently worked better than those using diatomaceous earth at generating rapid water loss in the bed bugs.
Turning to a more natural setting for bed bugs, the researchers set up a
|Contact: Joshua Benoit|
Ohio State University