Bed bugs’ ability to withstand inbreeding and still produce healthy offspring is one of the reasons just one or two introductions into a building can soon result in a serious infestations, researchers announced at the American Society of Tropical Medicine and Hygiene (ASTMH) annual meeting. After virtually disappearing in the 1950s, Cimex lectularius, the common bed bug, has returned in a big way over the last ten years.Bed bugs have also
developed resistance to pyrethroids, a type of insecticide that used to be much
more effective in controlling them.
ASTMH researchers also offered new
ways of controlling these pests in apartments and houses. They say it is
possible to prevent insecticide resistance. There are new compounds about that
can attract and repel them, they added.
Bed bugs are blood-suckers.
However, they do not transmit disease. They provoke allergic reactions,
including itching and inflamed welts. They are known as pests that pose an
economic and social threat to residents and owners of homes, apartment
buildings, public buildings and hotels. Controlling them can be costly.
Rajeev Vaidyanathan, PhD, associate director of Vector Biology and Zoonotic
Disease at SRI International,said:
“New York City alone spends between $10 million and $40 million per
year on bed bug control, and these numbers are repeated in other major cities
across the US.
Over 95 percent of pest control agencies reported bed bugs
as a priority in 2010, thus superseding termites as the number one urban
There are from ten to one hundred times more reports
of infestations today in hotel rooms, apartment blocks, and family homes
compared to twenty years ago, the researchers explained. Scientists are still
not completely sure why.
Bed bugs are able to inbreed without
compromising their genetic integrity, i.e. they can still produce healthy young
– this means that you only need a few of them to start a serious
Coby Schal, PhD, and Ed Vargo, PhD, from North Carolina
State University (NCSU), set out to examine the genetics of bed bugs. They
performed two studies on three apartment buildings in New Jersey and North
Carolina. They found that within each apartment the bugs were very closely
related – there was an extremely low genetic diversity within each single
building. This means that each infestation started off with a very small number
of bugs. Their studies are currently being peer-reviewed.
If bed bugs are
able to inbreed and still produce healthy offspring, they can spread easily from
one apartment to the next in the same building rapidly.
The team carried
out a separate study which looked at 21 infestations from Florida to Maine. In
virtually all cases, the source was a single room within a
“Inbreeding gives bed bugs an advantage in being able to colonize. A
single female that has been mated is able to colonize and start a new
infestation. Her progeny and brothers and sisters can then mate with each other,
exponentially expanding the population. With many organisms, extensive
inbreeding would cause serious mutations that would eventually bring about an
end to the population.”
The researchers added that
cockroaches also appear to be successful inbreeders.
How to overcome insecticide resistance
bugs have become progressively resistant to previously effective insecticide
treatments. A new study has shown that it is possible to neutralize the
mechanism that makes the bed bug resistant to pyrethroids
Ken Haynes, PhD, an entomologist from the University of
Kentucky and team have been researching on bed bug insecticide resistance.
Collaborators, Subba Reddy Palli and Fang Zhu targeted specific enzymes within
the insects that are linked to the P450 detoxification system that breaks down
the insecticides before they reach their targets. They used RNA interference
against the P450 family enzymatic partner to selectively switch off the system
inside the bed bugs, thus preserving the efficacy of deltamethrin (the
Better traps and detectors
Bed bug behavior is
influenced by several compounds. Scientists say they are discovering new ones.
If they can identify and understand what the functions of chemical compounds the
bed bugs secrete are, they might have a better chance of controlling
Vaidyanathan and team isolated seven new bed bug compounds
that had never been detected before. These could become attractants (to attract
the bugs). The idea is to create a cocktail of these compounds to attract the
pests into a trap.
Entomologist, Mark Feldlaufer, PhD, who works in the
US Department of Agriculture’s Agricultural Research Service, is carrying out
research into pheromones that can influence bed bug behavior. There are some
alarm compounds that warn insects of the same species that there is
danger – the team has examined their chemical blueprint.
investigation discovered which chemicals are associated with the outer skeleton
of bed bugs. He is trying to find out whether dogs might be able to sniff out
some of these chemicals, i.e. sniff out bed bugs. Dogs are used by professionals
in pest management to seek out pests, just as they are used to find drugs, lost
people and explosives.
Bed bugs and humans
“Bed bugs are our oldest roommates. There is even evidence of bed
bugs in Pharaonic Egypt. The problems we are seeing with bed bugs in North
America did not happen overnight. They are the consequence of multiple repeated
introductions from all over the world.
We have the highest concentration
in the history of our species of humans living in cities. For as long as we’ve
been standing on two legs, we’ve lived in rural areas. Over the last ten years,
the majority of humans have moved to urban areas.
This is the perfect
setting for creating a high density of mammal nests for bed bugs. Bed bugs do
not have wings; they are nest parasites, so our own population density has
helped them to thrive.”
Within a single building the genetic
diversity of bed bugs is limited. However, the NCSU scientists explain that the
genetic diversity of bed bugs throughout East Coast high – the pests come from
several places, from both within the USA and abroad.
international travel is a major factor in the increase of bed bug infestations.
Industrial poultry production is another – bed bugs feed on chickens. Household
furniture and items are also partly responsible for the explosion in the number
of reported infestations in the USA.
Insecticides and heat treatment for infestation
Heat treatment and insecticides are currently used to deal with
infestations. Insecticides which humans have easy access to have not usually
been tested on bed bugs, the researchers stressed.
With heat treatment
you heat the whole home – furniture and belongings can be packed in boxes and
heated at a high temperature for about sixty minutes. These options are
expensive and not suitable for long-term infestations. President of ASTMH, Peter
J. Hotez, MD, PhD, said:
“Just as with other global diseases once thought under control and
then neglected, bed bugs have shown the ability to resurge in great numbers once
our vigilance wanes.To stay one step ahead of bed bugs and other parasitic
organisms, we need to sustain investment in research for new