Scientists have determined that combining bed bugs’ own chemical signals with a common insect control agent makes that treatment more effective at killing the bugs.
The researchers found that stirring up the bed bugs by spraying their environment with synthetic versions of their alarm pheromones makes them more likely to walk through agents called desiccant dusts, which kill the bugs by making them highly susceptible to dehydration.
A blend of two pheromones applied in concert with a silica gel desiccant dust proved to be the most lethal combination.
In the past decade, bed bugs have become an increasing problem in industries ranging from agriculture and housing to travel and hospitality, so much so that the Environmental Protection Agency hosted a National Bed Bug Summit in April of this year.
These results were achieved in small areas, but Benoit and colleagues hope the technique could also be applied to large environments infested with bed bugs. Benoit is reluctant to suggest the use of desiccant dusts with alarm pheromones until additional experiments are conducted.
The species, Cimes lectularius, also is developing resistance to the insecticides approved to spray infested areas, treatments that belong to a group of compounds called pyrethroids.
Desiccant dusts that are sprinkled in infested areas, however, are among the oldest forms of insect control and are still considered effective killers as long as the bugs walk through them.
“Once we put the alarm pheromone in the places bed bugs hide, boom, they instantly started moving around and moving through the desiccant dust,” said Joshua Benoit, lead author of the study and a doctoral candidate in entomology studying under David Denlinger at OhioStateUniversity.
“Consistently, the addition of a pheromone blend to desiccant dust was more effective than adding either chemical by itself or by using desiccant dust alone.”
The research is published in the current issue of the Journal of Medical Entomology.
The two bed bug alarm pheromone ingredients are known as (E)-2-hexenal and (E)-2-octenal. When bed bugs are disturbed or excited, they secrete these two pheromones and tend to want to move around.
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.
