Identification Guide to Adult Mosquitoes in Mississippi - MSUcares

113 Pages·2012·12.66 MB·English

Identification Guide
to Adult Mosquitoes
in Mississippi
es
Identification Guide to Adult Mosquitoes in Mississippi
By Wendy C. Varnado, Jerome Goddard, and Bruce Harrison
Cover photo by Dr. Blake Layton, Mississippi State University Extension Service.
Preface
Entomology, and Plant Pathology at Mississippi
State University, provided helpful comments and
Mosquitoes and the diseases they transmit are in-
other support for publication of this book. Most
Identification and Geographical Distri-
creasing in frequency and geographic distribution.
figures used in this book are from Darsie, R. F. and
bution of the Mosquitoes of North America, North
As many as 1,000 people were exposed recently
Ward, R. A.,
of Mexico
to dengue fever during an outbreak in the Florida
Mos-
Keys. “New” mosquito-borne diseases such as
, University Press of Florida, Gainesville,
quitoes of North America
West Nile and Chikungunya have increased pub-
FL, 2005, and Carpenter, S. and LaCasse, W.,
lic awareness about disease potential from these
, University of California
notorious pests.
Press, Berkeley, CA, 1955. None of these figures are
This book was written to provide citizens,
protected under current copyrights.
Introduction
public health workers, school teachers, and other
interested parties with a hands-on, user-friendly and Background
guide to Mississippi mosquitoes. The book’s util-
ity may vary with each user group, and that’s OK;
some will want or need more detail than others.
There has never been a systematic, statewide
Nonetheless, the information provided will allow
study of mosquitoes in Mississippi. Various au-
you to identify mosquitoes found in Mississippi
thors have reported mosquito collection records
with a fair degree of accuracy. For more informa-
as a result of surveys of military installations in
tion about mosquito species occurring in the state
the state and/or public health malaria inspec-
and diseases they may transmit, contact the ento-
tions. The first published mosquito records from
mology staff at the Mississippi State Department of
Mississippi resulted from an anopheline survey
Health or the medical entomologist at Mississippi Anopheles crucians An. punctipennis An.
(malaria-related) in 1927 in which the authors
State University. pseudopunctipennis An. quadrimaculatus
Acknowledgements
reported , ,
, and (Car-
ley and Balfour 1929). Two years later, another
An. quadrimaculatus An. punctipennis An.
This publication would not have been possible mcraulcairainas study in the Mississippi Delta reported
without the help and support of several individu- , , aAnndo pheles
als and state and federal governmental funding (Perez 1930). A paper published in 1940
sources. Dr. Sally Slavinski, formerly with the by the State Board of Health discussed
Mississippi State Department of Health (MSDH), population densities in Mississippi but reported
helped first establish the West Nile virus surveil- no specific species names (Bradley, Bellamy et al.
lance program in 2001. Tim Darnell, Office of Envi- 1940). During the 1940s, several military-related
ronmental Health, MSDH, supported the mosquito studies in Mississippi provided further records of
survey and identification project from inception, as mosquitoes (King and Bradley 1941; King, Roth et
did Dr. Ed Thompson (former state health officer, al. 1943; Middlekauff and Carpenter 1944; Car-
MSDH) and Dr. Mary Currier (current state health penter, Chamberlain et al. 1945; Miles and Rings
officer, MSDH). Partial funding came from a grant 1946; Michener 1947; Rings and Richmond 1953).
from the Centers for Disease Control and Preven- Michener’s work was the most complete, revealing
tion to the Mississippi State Department of Health 47 species from the Camp Shelby (Hattiesburg)
titled “Epidemiology and Laboratory Capacity for vicinity of South Mississippi (Michener 1947). In
Infectious Diseases (West Nile surveillance por- addition, a sPtsuodryo pohno crhae cmonicfainl nciosntrocl oolfu rmicbei afieeld
tion),” U50\CCU416826-03. A health department mosquitoes in 1952 and 1953 in Bolivar County
contract mosquito surveillance technician, M’Lee mentioned (as )
Hoyt Loe, collected several thousand specimens (Mathis et al. 1954). Later, the results of these
from around the state from 2001 to 2003. Joe earlier records were summarized and provided a
MacGown, Dr. Blake Layton, and Dr. Scott Willard, total of 53 species occurring in Mississippi (King et
Department of Biochemistry, Molecular Biology, al. 1960).
3
Unusual Mosquito
In 1969, the U.S. Department of Agriculture Records from Mississippi
conducted mosquito surveillance in Hancock
County as part of a pest-monitoring program. All
collections were made in February and March and
There are several unusual mosquito collection
Ae. stimulans
yielded only 10 relatively common species (USDA
records from Mississippi. King et al. (1960) men-
1969). In the mid-1960s, Harden and Poolson
tioned a record of two from Electric
(1969) published a study to determine the season-
Mills in Kemper County, Mississippi. Finding these
ality of mosquitoes in Hancock County. During a
two specimens several hundred miles south of
4-year collection period (1964–1968), a total of 33
their normal range is quite strange; however, the
species was recorded. Almost all records from the
record has been confirmed and accepted as a valid
Ae. dorsalis
1970s, 1980s, and early 1990s resulted from col-
Mississippi record (Goddard and Harrison 2005).
lections made by U.S. Air Force personnel at instal-
There is also a collection record of
Aedes dorsalis
lations in Harrison and Lowndes counties (USAF
from Como, Mississippi (Miles and Rings 1946).
1971; USAF 1975; USAF 1977; USAF 1978; USAF
is ordinarily only found in the
1979; USAF 1980; USAF 1981; USAF 1983; USAF
western United States. Even though we have no
1984; USAF 1986; USAF 1987; USAF 1988).
Aedes albopictus voucher available, the specimen was apparently
Records from 1989 show the first known pres-
identified by Alan Stone, one of the foremost dip-
ence of the introduced species in
tera experts in the country, so we must accept this
Ps. pygmea
Mississippi (USAF 1989). A master’s thesis in 1974
as a valid Mississippi record.
by Harry Fulton determined the seasonality of
Harden et al. (1967) mentioned
mosquitoes in Clay, Lowndes, and Oktibbeha coun-
from Horn Island, Mississippi. Again, we have no
ties. A total of 39 species was collected from March
specimen available. Goddard and Harrison (2005)
1972 to November 1973 during his study. Some of
Anopheles walkeri Orthopodomyia alba Culex addressed this issue and determined that since
the most interesting findings in his survey includ-
pilosus Cx. peccator this species is restricted to southern Florida and
ed , ,
no voucher specimen is available, the record must
Ae. nigromaculis
, and (Fulton 1974; Fulton et al.
Wyeomyia be deleted.
1974). In 1977 and 1983, Bradshaw published two
smithii There is one record of from
Ae. nigromaculis
papers on the pitcher-plant mosquito
Harrison County, Mississippi (USAF 1990). The
in Mississippi, with both papers reporting
distribution of borders the west-
collections from George County. He noted that the
Sarracenia purpurea ern edge of Mississippi (Darsie and Ward 2005), so
mosquito was found associated with the purple
finding this species in Mississippi is certainly pos-
pitcher-plant, , and its hybrids
sible. Nonetheless, we have no voucher specimen
(Bradshaw and Lounibos 1977; Bradshaw 1983).
and thus no positive verification of this species
In 1982, Nelson conducted a small study at Mays
from Mississippi.
Mosquito Taxonomy and
Lake in Jackson, Mississippi, to determine the
relative abundance and species composition of the Reclassification Issues
mosquito population (Nelson et al. 1985). During
the months of March through September 1982, a
total of 13 species from five genera were recorded.
For mosquito identification/surveillance, we use
In the late 1990s, research was conducted in
the illustrations in Carpenter and LaCasse (1955)
northeast Mississippi to determine arbovirus ac-
and the keys of Darsie and Ward (2005), Slaff and
tivity in the adult mosquito population. Traps were Aedes
Apperson (1989), and Darsie and Morris (2000).
set in a wetland in Tishomingo County to collect
We have accepted the recent changes in
mosquitoes for arboviral testing and to determine Ochlerotatus
nomenclature by Reinert (2000) and recognize
species diversity. A total of 23 species was col- Aedes
as the genus for certain species that
lected (Cupp et al. 2004).
were formerly in the genus . Abbreviations
Anopheles quadrimaculatus
for genera follow Reinert (2001). As for species
complex, s.l., we have
4
accepted the Reinert et al. (1997) classification representing 57 of the 61 species discussed are
An. diluvialis An. inundatus An. maverlius
that there are five species in this complex consist- deposited in the Mississippi Entomological Muse-
An. quadrimaculatus An. smaragdinus
ing of , , , um or in the Smithsonian Institution. Nine species
An. maverlius An. quadrimacula-
, and . Three have been reported for which specimens have not
tus An. smaragdinus
of these species ( , been examined by the authors or verified as valid.
Basic Mosquito
, and ) have been recorded from
Mississippi (Reinert et al. 1997). Biology and Ecology
Recent Mosquito
Work in Mississippi
Mosquitoes undergo complete metamorphosis,
having egg, larval, pupal, and adult stages. Larvae
In 2000, the Mississippi State Department of are commonly referred to as “wigglers” and pupae
Health received a West Nile surveillance grant as “tumblers.” Larvae and pupae of mosquitoes
from the Centers for Disease Control. This grant are always found in water. Breeding sites may be
provided funding for more intensive mosquito anything from water in discarded automobile tires
collecting and West Nile testing in selected areas and the axils of plants, to pools, puddles, swamps,
around the state. As a result, several new state and lakes. It is very important to note that mos-
records for mosquitoes have been found. quito species differ in their breeding habits, biting
In 2005, Goddard and Harrison (2005) de- behavior, flight range, and so forth. However, a
Mansonia tittilans
scribed two of these new state records. One was generalized description of their life cycle is pre-
, which was recorded from Madi- sented here as a basis for understanding mosquito
Ochlerotatus trivittatus
son (2000), Copiah (2000), and Rankin counties biology and ecology.
(2003), and the other was There are two subfamilies in the mosquito fam-
from Marshall County. ily (Culicidae): Anophelinae and Culicinae. Most
Culex coronator
The most recent new Mississippi mosquito larvae in the subfamily Culicinae hang down just
records are , collected in November under the water surface by the siphon, whereas
Ochlerotatus japonicus,
2004 from Copiah County (Varnado et al. 2005), anopheline larvae lie horizontally just beneath the
Culex
and collected in 2011 water surface supported by small notched organs
coronator
from Itawamba County (Thorn et al. 2012). of the thorax and clusters of float hairs along the
is typically located in Central and South abdomen. They have no prominent siphon. Mos-
America. Previously, this species was only collect- quito larvae feed on suspended particles in the
ed in the United States from Arizona, New Mexico, water as well as microorganisms. However, there
and Texas. are a few species that capture and eat other spe-
Many gaps remain in our knowledge of Mis- cies. They undergo four molts (each successively
sissippi mosquitoes. Despite increased mosquito larger), the last of which results in the pupal stage.
surveillance, thanks to CDC funding, there remains With optimal food and temperature, the time re-
a need for a systematic statewide mosquito survey. quired for development from larva to adult can be
This publication summarizes the knowledge as short as 7 days.
on mosquitoes occurring in Mississippi. Many The pupal stage of mosquitoes does not feed.
of the distribution records used to generate this Pupae give rise to adult mosquitoes in 2 to 4 days.
list of species are the result of extensive collect- The emergence process begins with splitting of
ing conducted by the authors from 2003 to 2007 the pupal skin along the back. An emerging adult
throughout much of the state. In addition, a con- must dry its wings and groom its head appendages
tract mosquito surveillance technician (M’Lee Loe) before flying away. Accordingly, this is a critical
collected several thousand records from around stage in the survival of mosquitoes. If there is too
the state from 2001 to 2003. The collection re- much wind or wave action, the emerging adult will
cords and literature show 61 species occurring or fall over, becoming trapped on the water surface
having occurred in Mississippi. Voucher specimens to die. This is the reason that little if any mosquito
5
breeding occurs in open water; it occurs at the easily when first laid. However, after embryo de-
water’s edge among weeds. velopment with each egg, the eggs can withstand
Aedes/Ochlerotatus
Adult mosquitoes of both sexes obtain nourish- dry conditions for long periods of time. This trait
ment for basic metabolism and flight by feeding on has allowed mosquitoes to use
nectar. In addition, females of most species need a temporary water bodies for breeding, such as arti-
blood meal from birds, mammals, or other verte- ficial containers, periodically flooded salt marshes
Aedes/Ochlerotatus
brates for egg development. They suck blood via or fields, tree holes, and storm water pools. Also,
specialized piercing-sucking mouthparts. mosquitoes have inadvertently
Breeding sites selected for egg-laying differ by been carried to many parts of the world as dry
Ochlerotatus
species, but generally mosquitoes can be divided eggs in tires, water jars, or other containers.
taeniorhynchus Oc. sollicitans
into three major groups: permanent water breed- Salt marsh mosquitoes, such as
Anopheles Culex
ers, floodwater breeders, and artificial container/ and , breed in salt
tree hole breeders. and many marsh pools flooded by tides and/or rain and
mosquitoes select permanent water bodies, such periodically emerge in great swarms, making
as swamps, ponds, lakes, and ditches, that do not outdoor activity in large areas of seacoast unbear-
Psorophora
usually dry up. Floodwater mosquitoes lay eggs able. Their flight range is between 5 and 10 miles,
on the ground in low areas subject to repeated but they can travel 40 miles or more.
flooding. During heavy rains, water collecting in mosquitoes also lay dry-resistant eggs. These mos-
these low areas covers the eggs, which hatch from quitoes are a major problem species in rice fields.
Ochlerotatus sollicitans Psorophora
within minutes to a few hours. Salt marsh mosqui- Eggs are laid on the soil and hatch once the rice
Aedes vexans Ps. columbiae
toes ( ), inland floodwater field is irrigated. mosquitoes may also
Psorophora columbiae
mosquitoes ( ), and dark rice field emerge in huge swarms. In 1932, is
mosquitoes ( ) are included reported to have caused a great loss of livestock
in this group. Artificial container/tree hole breed- in the Everglades, and the milk supply was greatly
Ae. aegypti Ae. albop-
ers are represented by yellow fever mosquitoes reduced during the 4 days of the infestation (Har-
ictus Oc. triseriatus Culex
( ), Asian tiger mosquitoes ( wood and James 1979).
Anopheles
), tree hole mosquitoes ( ), and mosquitoes lay batches of eggs attached
Culex
others. However, several species of and together to form little floating rafts. On close in-
may also occasionally oviposit in these areas. spection of a suitable breeding site, these egg rafts
Culex
Some of these container-breeding species lay eggs can often be seen floating on the water’s surface.
on the walls of a container just above the water Where breeding conditions are favorable,
Culex
line. The eggs are flooded when rainfall raises the mosquitoes also occur in enormous numbers. Sev-
water level. Other species oviposit directly on the eral species are notorious for their aggravat-
Anopheles
water surface. ing high-pitched hum when flying about the ears.
Female mosquitoes generally lay In tropical areas, mosquito breeding may con-
eggs on the surface of the water at night. Each tinue year-round, but in temperate climates, many
Anopheles
batch usually contains 100 to 150 eggs. Each species undergo a diapause in which the adults
egg is cigar-shaped and about 1 mm enter a dormant state similar to hibernation. In
long, and bears a pair of air-filled floats on the preparation for this, females become reluctant
Anopheles
sides. Under favorable conditions, hatching occurs to feed, cease ovarian development, and develop
within 72 hours. mosquitoes may oc- fat body. In addition, they may seek a protected
cur in extremely high numbers. In the Mississippi place to pass the approaching winter. Some spe-
An. quadrimaculatus
Delta, mosquito trapping has yielded as many as cies, instead of passing the winter as hibernating
Aedes Ochlerotatus
9,000 per trap, per night! adults, produce dormant eggs or have larvae that
and mosquitoes lay their can survive the harsh effects of winter.
eggs on moist ground around the edge of the water Mosquitoes vary in their biting patterns. Most
or, as previously mentioned, on the inside walls species are nocturnal in activity, biting mainly in
Aedes/Ochlerotatus Ae. aegypti Ae. albopictus
of artificial containers just above the water line. the early evening. However, some species, especial-
eggs will desiccate and perish ly and , bite in broad day-
6
West Nile Virus Encephalitis
light (although there may be a peak of biting early
Psoropho-
and late in the day). Others, such as salt marsh West Nile virus (WNV) was introduced into the
ra
species and many members of the genus United States in 1999 and has since spread across
ordinarily bite during the night but will attack if the country (CDC 1999; CDC 2007a). The disease
disturbed during the day (such as walking through is maintained in nature in a manner similar to
high grass harboring resting adults). St. Louis Encephalitis, in a bird-mosquito cycle,
Mosquitoes and Culex
although humans and horses are incidental hosts.
Culex quinquefasciatus Cx. pipiens Cx. tarsalis
Human Disease Several spp., including the common mosqui-
Cx. salinarius Cx. restuans
toes , , ,
and and possibly , are
the principal vectors to people (Hayes et al. 2005).
Mosquitoes may impact human health directly
WNV appears to be most dangerous to elderly or
through nuisance biting (and sometimes second-
immune-compromised patients. Since WNV has
ary infection afterwards) or indirectly through
been demonstrated to amplify in the Asian tiger
disease transmission (Goddard 1994; McHugh
mosquito in the laboratory and WNV-positive
1994; Goddard 2004). Although malaria, yellow
pools of this mosquito have been detected, it is
fever, and dengue could possibly return to the
possible that this mosquito could also be involved
United States and begin spreading, the primary
in WNV transmission. In contrast to other mos-
threat from mosquito-borne disease comes from
quito-borne viruses, WNV also kills many birds in
the encephalitis viruses. There are several such
the United States, especially crows, blue jays, and
viruses circulating in the United States, leading to
raptors.
thousands of cases each year.
St. Louis Encephalitis
Surveillance efforts to detect the presence of
WNV in Mississippi, therefore, sometimes targets
Culex
the reporting and testing of those three types of
St. Louis Encephalitis (SLE) virus circulates natu-
dead birds. WNV does not generally cause as seri-
rally among birds and is transmitted by mos-
ous illness as some other arboviral diseases (e.g.,
quitoes. Humans can become infected only if bitten
EEE, SLE). In fact, only one out of every 150 to 200
by an infected mosquito. Humans are actually
people exposed to the virus will become ill, and
“dead end” hosts, meaning that the virus in human
less than 10 percent of clinically ill patients will
blood never reaches a level high enough to infect a
die (Hayes et al. 2005). Still, the public’s percep-
biting female mosquito to continue the cycle. Not
tion and reaction to local reports of WNV cases
all people infected with the virus develop clinical
causes much anxiety and fear in communities.
disease. However, SLE may produce abrupt fever,
Local officials are, then, pressured by the public to
nausea, vomiting, and severe headache in humans
provide mosquito control to protect them.
within 5 to 7 days after being bitten. Fatality rates Eastern Equine Encephalitis
range from 2 to 20 percent, with most deaths oc-
curring in people 60 years of age or older (Monath
Eastern Equine Encephalomyelitis (EEE) is the
1980).
most severe of all the mosquito-borne encephali-
Outbreaks of SLE usually occur in midsummer
tis diseases in Mississippi (Morris 1988). As with
to early fall. Since wild birds and domestic fowl Culiseta melanura
Culex
SLE and WNV, birds are the primary hosts, and
are the reservoirs of this virus, urban areas where Cs. melanura
mosquitoes, particularly , are the
large bird populations and abundant mos-
vectors from bird to bird. However,
quitoes are found together are prime sites for a
rarely feeds on humans. People usually become in-
disease outbreak. A major SLE outbreak occurred Ochlerotatus
fected with EEE as dead-end hosts when fed upon
in Mississippi in 1975 (Powell and Blakey 1976; sollicitans Aedes
by infected salt marsh mosquitoes (
Powell and Blakey 1977; Monath 1980). Numerous vexans Coquillettidia perturbans
), inland floodwater mosquitoes (
people were affected and many cases resulted in
), , and a few other
death. The threat for this to happen again is real.
species.
7
The disease will affect people of any age, with or coma (Cunnion et al. 1984; Gilles and Warrell
young children and infants being the most suscep- 1993). Falciparum malaria may also produce com-
tible. The mortality rate is more than 50 percent, plications such as renal failure, hemolytic anemia,
and children surviving the disease often suffer hypoglycemia, and acute pulmonary edema.
from some degree of mental retardation or paraly- Human malaria is caused by any one of five
Plasmodium Plas-
sis. Horses are often severely affected by the dis- species (four primary ones) of microscopic pro-
modium vivax P. malariae P. ovale P. falciparum
ease during outbreaks. However, a horse vaccine is tozoan parasites in the genus :
P. knowlesi
available. , , , ,
LaCrosse Encephalitis
and . The infective sporozoites are
Anopheles
transmitted to humans only by mosquitoes in the
Anopheles
In contrast to most other mosquito-borne viruses genus . However, not every species of
in Mississippi, LaCrosse (LAC) maintains its cycle is a vector; less than half of the 300 or
in nature via a small mammal-mosquito cycle. Usu- so known species are considered vectors. In fact,
Ochlerotatus triseriatus Plasmodium P.
ally, the mosquito vector is the tree-hole mosquito only 30 species are important vectors. Not all spe-
vivax
, and the reservoir is the cies of occur in all places. Generally,
P. ovale
gray squirrel. However, chipmunks may also be is prevalent throughout all malarious areas,
involved. Mississippi recorded its first confirmed except sub-Saharan Africa; is found chiefly
P. malariae
cases of LAC in 1967, but the disease was not often in tropical areas of western Africa (occasionally
diagnosed until eight cases were identified in western Pacific and southeast Asia);
P. falciparum
2001. LAC most often occurs in children younger is widely distributed around the world, but often
than 16 and can cause convulsive disorders in af- spotty; predominates in sub-Saharan
P. knowlesi
fected children (McJunkin et al. 2001). These facts Africa but also occurs in southeast Asia and South
may lead parents to demand that local officials America; occurs in southeast Asia.
Anoph-
implement control measures. It is believed that there are at least four malaria
Malaria eles freeborni An. hermsi
mosquito vectors in the United States:
An. punc-
(in the western U.S.), (a
tipennis An. quadrimaculatus
Malaria is the most common and devastating recently described species in the West),
An. quadri-
infectious mosquito-borne disease in the world (western U.S.), and
maculatus
today, with hundreds of millions of cases reported (eastern U.S.). As mentioned earlier,
An. diluvialis An. inundatus An.
annually from tropical and sub-tropical countries is actually a complex of five species
maverlius An. quadrimaculatus An. smaragdi-
(Sturcher 1989). Historically, the disease also oc- consisting of , ,
nus An. maverlius An.
curred in the temperate zone including Mississippi , , and
quadrimaculatus An. smaragdinus
(Goddard and Hataway 2011); however, intensive . Three of these subspecies ( ,
mosquito control efforts in the 1930s through , and ) have been
Anopheles
1950s, along with improvements in the standard recorded from Mississippi (Reinert et al. 1997).
of living (air conditioning and screening), elimi- Other species may also be involved in
nated the malady from the United States. Imported malaria transmission in the United States but are
cases still occur, and even occasional outbreaks of considered vectors of minor importance (Jensen et
locally transmitted malaria, but they are usually al. 1998). All four of the main vector species breed
quickly contained (Bradley et al. 1940; Harden et in permanent freshwater sites, such as ponds,
al. 1967; Zucker 1996; CDC 2004). pools, and rice fields, and are avid human biters.
Classic malaria includes symptoms such as fe- Accordingly, there is always the possibility of rein-
ver, chills, sweats, headache, muscle pain, and mal- troduction of the malaria parasite into the United
aise. There may be a repeating cycle of high fever States and resumption of indigenously acquired
and sweating. Infants may display only lethargy, ir- cases.
Dengue
ritability, and anorexia. In rare forms of falciparum
malaria (there are five different species of malaria;
see below), chills and fever may be absent, and the Dengue is a serious mosquito-borne human dis-
patient may present with medical shock, delirium, ease occurring in Asia and Africa, as well as in the
8
Aedes
Caribbean and in Central and South America. It is Dengue virus can be transmitted from person
aegypti Ae. albop-
caused by a flavivirus related to yellow fever virus, to person by the yellow fever mosquito (
ictus
which has four serotypes (Den 1, Den 2, Den 3, and ) and the Asian tiger mosquito (
Den 4). As far as is known, humans are the main ) (Goddard 1996; Gubler 1998). Generally,
vertebrate reservoir of the virus, although there other than humans, no bird or mammal reservoirs
may be a monkey-mosquito cycle in some areas. exist for dengue. A mosquito can become infected
The disease is characterized by fever, headache, with the virus by feeding on a person with the
retro-orbital pain, and intense aching; it is some- disease, then the virus must go through an 8- to
times referred to as “breakbone fever.” Occasion- 10-day incubation period in the mosquito before it
ally, a more severe form of the disease occurs, den- becomes infective. The mosquito will then remain
gue hemorrhagic fever/dengue shock syndrome infective for the rest of its life.
Dog Heartworm
(DHF/DSS), which may result in a hemorrhagic
shock syndrome with a fatal outcome.
Dengue is not an insignificant disease en- Dog heartworm is a serious canine disease in the
tity—there are approximately 50 million to 100 midwestern and eastern United States (Harwood
million cases each year (Gubler and Clark 1995; and James 1979). Almost 100 percent of unpro-
Spira 2005). Currently, it is not widespread in tected dogs more than 5 years old are infected.
this country (except in the Florida Keys), but it is Mosquito vectors that feed on an infected dog take
literally “knocking at the door” awaiting further in immature worms (first stage larvae) with the
spread. Hundreds of cases occurred in the summer dog’s blood. The immature worms undergo devel-
of 1995 along the Texas–Mexico border, especially opment within the mosquito, reaching an infec-
in the Reynosa area. A few cases were acquired on tive state (third stage larvae) in 9 to 14 days after
the U.S. side. Recently, there was a report of DHF entering the mosquito. These infective larvae can
in a resident of Brownsville, Texas (CDC 2007b), then be transmitted to an uninfected dog when the
and about 60 cases of dengue in the Florida Keys. mosquito feeds. The worms migrate to the dog’s
There is always the possibility of a widespread heart and grow into adults. These adult worms
dengue epidemic in the United States since there produce first stage larvae that circulate within the
is an abundance of the mosquito vectors in the dog’s blood and are taken up by feeding mosqui-
Culex quinquefasciatus
south-central United States. Also, with the thou- toes to continue the cycle. The southern house
sands of people returning home from cruises to mosquito ( ) is the primary
the Caribbean each month (especially during the vector of dog heartworm in Mississippi, although
summer), there is a good chance of infected people several other mosquitoes are involved.
returning and infecting local mosquitoes with the
virus.
Additional Resources
www.mosquito.org
American Mosquito Control Association
www.floridamosquito.org
Florida Mosquito Control Association
http://mississippientomologicalmuseum.org.msstate.edu/
Researchtaxapages/Mosquitoes/Introduction.html
Mississippi State University, Mosquito Webpage
Silver, J. B. (2008). Mosquito Ecology: Field Sampling Methods. Dordrecht, Springer.
9
References Cited
Southern Med J
Bradley, G. H., R. E. Bellamy, et al. (1940). “The work of state board of health entomologists on malaria con-
trol.” 33: 892-894.
Wyeomyia smithii Metriocnemus

knabi Sarracenia purpurea Phytotelmata: Terrestrial Plants as Hosts of Aquatic
Bradshaw, W. E. (1983). Interaction between the mosquito , the midge
Insect Communities
, and their carnivorous host .
. J. L. Franks and L. P. Lounibos. London, Plexus: 161-189.

Evolution
Bradshaw, W. E. and L. P. Lounibos (1977). “Evolution of dormancy and its photoperiodic control in pitcher-
plant mosquitoes.” 31: 546-567.

Southern Med. J
Carley, P. S. and M. C. Balfour (1929). “Prevalence of malaria in Humphreys and Sunflower Counties, Missis-
sippi, in 1927-1928.” . 22: 377-382.

J Econ Entomol
Carpenter, S. J., R. W. Chamberlain, et al. (1945). “New distribution records for the mosquitoes of the south-
eastern states in 1944.” 38: 402-403.
Mosquitoes of North America: North of Mexico

Carpenter, S. J. and LaCasse (1955). . Berkeley and Los Angeles,
University of California Press.

CDC (1999). Outbreak of West Nile-like viral encephalitis in New York, CDC, MMWR, 48: 845-848.

CDC (2004). Multifocal autochthonous transmission of malaria—Florida, 2003, CDC, MMWR, 53: 412-413.
CDC (2007a). West Nile virus activity—United States, 2006, CDC, MMWR, 56: 556-559.

CDC (2007b). Dengue hemorrhagic fever—U.S.-Mexico border, 2005, CDC, MMWR, 56: 785-789.

Cunnion, S., T. Dickens, et al. (1984). Navy medical department guide to malaria prevention and control, U.S.
Navy Environ. Hlth. Cntr., Norfolk, VA.

J Med Entomol
Cupp, E. W., K. J. Tennessen, et al. (2004). “Mosquito and arbovirus activity during 1997-2002 in a wetland
in northeastern Mississippi.” 41: 495-501.
Identification and Geographical Distribution of the Mosquitoes of North

America, North of Mexico
Darsie, R. F. and R. A. Ward (2005).
. Gainesville, University Press of Florida.

Entomology Department
Fulton, H. R. (1974). The Seasonal Occurrence of Mosquitoes in Clay, Lowndes, and Oktibbeha Counties,
Mississippi and Their Associated Pathogens. . Starkville, Mississippi State Univer-
sity. Master of Science: 54.
Bruce-Chwatt’s Essential Malariology

Gilles, H. and D. Warrell (1993). . London, Arnold Publishers.

Goddard, J. (1994). “Direct injury from arthropods.” Lab Med 25: 365-371.
Infect Med
Goddard, J. (1996). “Viruses transmitted by mosquitoes—dengue fever.” 13: 933-934.
Infect Med

Goddard, J. (2004). “Clinical consquences of mosquito bites.” 21: 373-376.
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