From Alzheimer’s to Zebrafish: Eclectic Science and Regulatory Stories 108
Pundits are predicting that global warming will result in unimaginable problems, includ-
ing the possibility that tropical diseases will become much more prevalent in the US. Also,
rainforests in Africa or in the Amazon region could disappear in this century, leading
certain disease-related insects to move on and create new breeding sites. If either occurs,
and both are likely, mosquitoes will no doubt be the vectors.
Mosquitoes are our most persistent and deadly enemy.1 They have killed great lead-
ers, decimated armies and decided the fates of nations. Alexander the Great, for example,
was likely killed by malaria in 323 BC.2 Mosquitoes are responsible for a host of devastat-
ing, difficult-to-treat diseases including dengue, elephantiasis and malaria, which affect
more than 10% of the world’s population. One bite is all it takes to be infected with West
Nile virus or other mosquito-borne diseases.3 Mosquitoes are also attracted to some people
more than others. Fortunately, they can be repelled by a number of chemicals whose repel-
lent performance can be predicted from their structure.
Mosquitoes are unique in terms of their numbers, varieties, lifecycles, geographic
distribution, appetites and habits. However, despite all we know about mosquitoes, a
number of mysteries remain. In light of the mosquito’s profound effects and potential
impact in the future, all of us should be better acquainted with this tiny insect, its mecha-
nisms of disease transmission and means of prevention. This article briefly discusses these
topics and provides a number of references for further reading.
General Information
Mosquitoes are arthropods: invertebrates with six legs and a pair of wings. Common
house mosquitoes (Culex pipiens) are 1/8”–1/4” in length. Each mosquito’s body has
three main parts: the head, which holds all of the sensory organs the thorax, to which
the wings and legs are attached and the abdomen, where digestion occurs. The head is
specialized for acquiring sensory information and for feeding. It contains the eyes and a
pair of long, multi-segmented antennae. Antennae are important for detecting host odors
as well as odors of breeding sites where females lay eggs. The head also has an elongated,
forward-projecting proboscis that females use for feeding. The proboscis consists of two
pairs of cutting stylets that stick together in a tight bundle called the fascicle, which lies in
a gutter-shaped sheath or labium.
Once a mosquito tastes blood, it holds still and begins sucking, and the sucking action
pulls the blood venule over its mouthparts. In about 90 seconds the mosquito ingests a
few micrograms of blood—two to three times its weight—into its stomach. The blood
meal consists not only of plasma and cells, but also any microorganisms that might be
developing inside these cells or floating free in the plasma. After feeding, the mosquito
will rest and allow its digestive system to draw water from the blood and excrete it in the
form of urine. This converts the blood to lighter solids that are stored for the future to feed
offspring. In the meantime, the mosquito has left behind its saliva, possibly containing
deadly microbes.4
There are approximately 3,500 mosquito species grouped into 41 genera.5 The “big
three” genera that transmit disease are various Anopheles species, Aedes aegypti and Culex
pipiens.6 Aedes aegypti is the primary vector for dengue and yellow fever. Human malaria
is transmitted only by females of the genus Anopheles. Culex pipens mosquitoes are the vec-
tors of West Nile virus and elephantiasis. Culiseta melanura is the main vector for eastern
equine encephalitis it circulates the virus among many kinds of birds but starlings are the
most important.7
Mosquitoes live all over the world and about 200 species dwell in North America.8
There may be as many as 1,000 trillion (1014) mosquitoes on the planet. Mosquitoes can
live five or six months, but few survive that long. Most live less than three weeks.9
Many mosquito species live in places that are warm, shady and damp, such as
swamps, forests and jungles. They prefer to live near water where they can deposit their
Pundits are predicting that global warming will result in unimaginable problems, includ-
ing the possibility that tropical diseases will become much more prevalent in the US. Also,
rainforests in Africa or in the Amazon region could disappear in this century, leading
certain disease-related insects to move on and create new breeding sites. If either occurs,
and both are likely, mosquitoes will no doubt be the vectors.
Mosquitoes are our most persistent and deadly enemy.1 They have killed great lead-
ers, decimated armies and decided the fates of nations. Alexander the Great, for example,
was likely killed by malaria in 323 BC.2 Mosquitoes are responsible for a host of devastat-
ing, difficult-to-treat diseases including dengue, elephantiasis and malaria, which affect
more than 10% of the world’s population. One bite is all it takes to be infected with West
Nile virus or other mosquito-borne diseases.3 Mosquitoes are also attracted to some people
more than others. Fortunately, they can be repelled by a number of chemicals whose repel-
lent performance can be predicted from their structure.
Mosquitoes are unique in terms of their numbers, varieties, lifecycles, geographic
distribution, appetites and habits. However, despite all we know about mosquitoes, a
number of mysteries remain. In light of the mosquito’s profound effects and potential
impact in the future, all of us should be better acquainted with this tiny insect, its mecha-
nisms of disease transmission and means of prevention. This article briefly discusses these
topics and provides a number of references for further reading.
General Information
Mosquitoes are arthropods: invertebrates with six legs and a pair of wings. Common
house mosquitoes (Culex pipiens) are 1/8”–1/4” in length. Each mosquito’s body has
three main parts: the head, which holds all of the sensory organs the thorax, to which
the wings and legs are attached and the abdomen, where digestion occurs. The head is
specialized for acquiring sensory information and for feeding. It contains the eyes and a
pair of long, multi-segmented antennae. Antennae are important for detecting host odors
as well as odors of breeding sites where females lay eggs. The head also has an elongated,
forward-projecting proboscis that females use for feeding. The proboscis consists of two
pairs of cutting stylets that stick together in a tight bundle called the fascicle, which lies in
a gutter-shaped sheath or labium.
Once a mosquito tastes blood, it holds still and begins sucking, and the sucking action
pulls the blood venule over its mouthparts. In about 90 seconds the mosquito ingests a
few micrograms of blood—two to three times its weight—into its stomach. The blood
meal consists not only of plasma and cells, but also any microorganisms that might be
developing inside these cells or floating free in the plasma. After feeding, the mosquito
will rest and allow its digestive system to draw water from the blood and excrete it in the
form of urine. This converts the blood to lighter solids that are stored for the future to feed
offspring. In the meantime, the mosquito has left behind its saliva, possibly containing
deadly microbes.4
There are approximately 3,500 mosquito species grouped into 41 genera.5 The “big
three” genera that transmit disease are various Anopheles species, Aedes aegypti and Culex
pipiens.6 Aedes aegypti is the primary vector for dengue and yellow fever. Human malaria
is transmitted only by females of the genus Anopheles. Culex pipens mosquitoes are the vec-
tors of West Nile virus and elephantiasis. Culiseta melanura is the main vector for eastern
equine encephalitis it circulates the virus among many kinds of birds but starlings are the
most important.7
Mosquitoes live all over the world and about 200 species dwell in North America.8
There may be as many as 1,000 trillion (1014) mosquitoes on the planet. Mosquitoes can
live five or six months, but few survive that long. Most live less than three weeks.9
Many mosquito species live in places that are warm, shady and damp, such as
swamps, forests and jungles. They prefer to live near water where they can deposit their