167
interest to recently fed females, and females receive approximately five traumatic insemi-
nations per feed, but not necessarily from the same male.12
Although female bed bugs possess a normal reproductive tract, males do not use
it for insemination, but instead they pierce the female’s abdominal wall. The sperm are
injected through the cuticle into the body cavity and must migrate through the haemocoel
to the female’s reproductive system.
Moreover, such traumatic or hypodermic mating is costly, occurring with an exces-
sive frequency that is roughly 20 times that necessary for egg fertilization. Each copulation
increases the risk of infection or physical damage in females and reduces their lifespan.13
This mating method is an evolutionary enigma, a characteristic limited to the
Cimicidae family of insects.14 How males encounter and recognize recently fed females
is unclear. Movement of any bed bug-size object in the vicinity produces an approach
response in males.15
Eradication
Recent studies show that bed bugs around the world have developed a resistance to the
chemicals used to control them. Laboratory tests in the US, Europe and Africa demon-
strate that today’s bedbugs can survive pesticide levels a thousand times greater than the
lethal dose of just a decade ago.16
Virtually all of these pests have evolved to resist the latest generation of pyrethroid
insecticides used to control them ever since dichloro-diphenyl-trichoroethane (DDT) was
banned about 40 years ago.17 Specifically, studies have found that bed bugs in New York
City have acquired mutations in their nerve cells which blunt the neurotoxic effect of the
pyrethroid toxins used against them.
The mutations affect the sodium channels in the neuron’s outer membrane, where
electrical impulses are produced. In scientific terms, resistance is purported to result from
point mutations in the open reading frames of voltage sensitive sodium channel genes
compared to pesticide sensitive populations.18
In the past, these nervous system poisons could effectively paralyze and kill the
bugs.19 Researchers are not sure how this resistance has spread but they do know from
molecular-biology studies that bed bugs have recently evolved at least three improved
biochemical defenses against common pesticides.
Bed bugs today appear to have nerve cells better able to withstand the chemical
effects, higher levels of enzymes that detoxify the lethal substances and thicker shells
that can block insecticides.20 One possibility to explain the resistance is that many tropical
countries have drastically scaled up mosquito control by spraying indoors and providing
bed nets impregnated with pyrethroids. This has increased the likelihood of resistance,
and global travel and trade could have introduced the already-resistant bugs to the US.
Another factor involved in the increased populations is in-breeding. A single female
that has been mated is able to colonize and start a new infestation. Her progeny and broth-
ers and sisters can then mate with each other, exponentially expanding the population.21
Clinical Consequences
It can be difficult to distinguish bed bug bites from other insect bites. In general, the sites
of such bites are red, often with a darker spot in the middle, itchy, arranged in a rough line
or in a cluster and located on the face, neck, arms and hands.22
Bed bugs attack exposed areas of the skin and are attracted to the human’s high body
temperature and carbon dioxide production.23 Patients exposed to numerous bed bugs
can present with a widespread erythematous rash or urticaria (itching). Anaphylaxis has
rarely been reported.
There is no evidence that bed bugs transmit human pathogens, but they are respon-
sible for significant psychological distress, can produce anemia when abundant and
Bed Bugs—Creatures of the Night!
interest to recently fed females, and females receive approximately five traumatic insemi-
nations per feed, but not necessarily from the same male.12
Although female bed bugs possess a normal reproductive tract, males do not use
it for insemination, but instead they pierce the female’s abdominal wall. The sperm are
injected through the cuticle into the body cavity and must migrate through the haemocoel
to the female’s reproductive system.
Moreover, such traumatic or hypodermic mating is costly, occurring with an exces-
sive frequency that is roughly 20 times that necessary for egg fertilization. Each copulation
increases the risk of infection or physical damage in females and reduces their lifespan.13
This mating method is an evolutionary enigma, a characteristic limited to the
Cimicidae family of insects.14 How males encounter and recognize recently fed females
is unclear. Movement of any bed bug-size object in the vicinity produces an approach
response in males.15
Eradication
Recent studies show that bed bugs around the world have developed a resistance to the
chemicals used to control them. Laboratory tests in the US, Europe and Africa demon-
strate that today’s bedbugs can survive pesticide levels a thousand times greater than the
lethal dose of just a decade ago.16
Virtually all of these pests have evolved to resist the latest generation of pyrethroid
insecticides used to control them ever since dichloro-diphenyl-trichoroethane (DDT) was
banned about 40 years ago.17 Specifically, studies have found that bed bugs in New York
City have acquired mutations in their nerve cells which blunt the neurotoxic effect of the
pyrethroid toxins used against them.
The mutations affect the sodium channels in the neuron’s outer membrane, where
electrical impulses are produced. In scientific terms, resistance is purported to result from
point mutations in the open reading frames of voltage sensitive sodium channel genes
compared to pesticide sensitive populations.18
In the past, these nervous system poisons could effectively paralyze and kill the
bugs.19 Researchers are not sure how this resistance has spread but they do know from
molecular-biology studies that bed bugs have recently evolved at least three improved
biochemical defenses against common pesticides.
Bed bugs today appear to have nerve cells better able to withstand the chemical
effects, higher levels of enzymes that detoxify the lethal substances and thicker shells
that can block insecticides.20 One possibility to explain the resistance is that many tropical
countries have drastically scaled up mosquito control by spraying indoors and providing
bed nets impregnated with pyrethroids. This has increased the likelihood of resistance,
and global travel and trade could have introduced the already-resistant bugs to the US.
Another factor involved in the increased populations is in-breeding. A single female
that has been mated is able to colonize and start a new infestation. Her progeny and broth-
ers and sisters can then mate with each other, exponentially expanding the population.21
Clinical Consequences
It can be difficult to distinguish bed bug bites from other insect bites. In general, the sites
of such bites are red, often with a darker spot in the middle, itchy, arranged in a rough line
or in a cluster and located on the face, neck, arms and hands.22
Bed bugs attack exposed areas of the skin and are attracted to the human’s high body
temperature and carbon dioxide production.23 Patients exposed to numerous bed bugs
can present with a widespread erythematous rash or urticaria (itching). Anaphylaxis has
rarely been reported.
There is no evidence that bed bugs transmit human pathogens, but they are respon-
sible for significant psychological distress, can produce anemia when abundant and
Bed Bugs—Creatures of the Night!