Life
History of the Malaria Parasite
(Plasmodium
vivax) in Man and
the
Anopheles Mosquito
Note:
By 1995 at least 1 of 4 species of the Plasmodium parasite that infect
humans, e.g., Plasmodium vivax, P. falciparum, P. malariae and P. ovale, were
found living in the blood of nearly 300 million people.
Malaria is transferred to humans only via mosquitoes and now affects 300
- 500 million new people per year and kills 1.5 to 2.7 million people per year.
Quinine no longer can control malaria - the disease has developed
resistance to it. Malaria is found
in at least 102 countries. In 395 A.D. 330,000 acres of farmland in Rome’s Compania
region were abandoned due to a malaria epidemic - Rome fell 81 years later.
PEST OVERVIEW
General
Description
Mosquitoes
are blood-feeding ectoparasites of people and animals.
The English call mosquitoes “gnats”.
There are about 100 trillion mosquitoes with at least 3,450 different
species in the world. They are
found from the tropics to the Arctic regions.
All of the families belong to the order Diptera and are related to house
flies, gnats and midges. What makes
mosquitoes different from all other flies is the presence of a long, piercing
mouthpart called a proboscis and the scales on the hind margins and veins of
their wings. Morphologically,
mosquito males differ from females in that they have feathery antennae, long
feathery palps and smaller mouthparts. Mosquitoes
develop through complete metamorphosis and have four distinct states: egg, larva
or “wriggler”, pupa or “tumbler” and adult.
Mosquito eggs can be
classified into three groups: 1.
eggs laid singly on the still or very slow-moving water surface (Anopheles),
with each egg having a series of “floats” along its perimeter; 2.
eggs laid in groups forming rafts made by the adult females that float on
water surfaces (Culex and Culiseta); and 3. eggs laid singly out of the water in the mud (Aedes and
Psorophora). Mosquito larvae
are aquatic; they feed on water mites, water fleas, algae, protozoans and minute
organic debris by sweeping the food into their mouths with a pair of feeding
brushes. Mosquito pupae also live
in the water. Adult mosquitoes are
small, about 1/8" long, with a single pair of membranous wings and are free
living. A typical mosquito weights
about 2.5 milligrams, or about 20,000 mosquitoes per pound. Males do not feed as adults, but females of most species
require a human and/or animal blood meal before oviposition, utilizing the
protein in blood to produce their eggs and bring them to maturity.
There are an estimated 10 trillion mosquitoes produced just in the U. S.
each summer with about 170 species. To
give you some idea how many 10 trillion is - that amounts to 41,000 mosquitoes
for every man, woman and child or enough to fill the entire Grand Canyon!
A mosquito’s brain is the size of the period at the end of this
sentence, yet it has outwitted man since the dawn of recorded history!
Mosquitoes seriously
harm vast numbers of people worldwide
by transmitting pathogenic organisms that cause disease and death, especially in
tropical areas. Including Eastern,
Western, California and St. Louis encephalitis, heartworm, malaria, yellow
fever, dengue and filariasis. Malaria
is a constant threat even in the United States where known vectors exist.
Malaria, among all insect-borne diseases, has been the most deadly in
modern history. During this century
alone it has killed between 100-300 million people, mostly babies and small kids
and it infects and debilitates hundreds of millions of others each year per WHO!
CNN Trivia 2/4/98 noted that 700,000,000 people a year are infected by
diseases carried by mosquitoes. In
comparison, only 21 million people died in combat in World War I, World War II
and the Korean War combined. Over
60 species of Anopheles mosquitoes are known to be capable of transmitting
malaria. Travelers returning from
abroad can constantly introduce the causal agents of malaria, which are
microscopic protozoa in the genus Plasmodium spp.
On average, one person dies every 10 seconds as a result of a
little mosquito “bite”. In Canada hordes of mosquitoes can actually darken the
sky - researchers were bitten about 9,000 times per minute; at that rate they
could lose 1/2 their blood in 2 hours and die from blood loss!
But our primary reason for controlling mosquitoes usually is only to
lessen the annoyance caused by their bites and then only secondarily to reduce
the transmission of human and equine viral encephalitis and dog heartworm.
The annoyance caused by mosquito feeding can include the itching,
restlessness, loss of sleep and nervous irritation in all people, pets and
domestic animals that suffer from their attacks.
Mosquitoes do not really “bite”, but they penetrate their victim’s
hide or skin with their proboscis or hollow, flexible snout.
The female has a pump in her head which she uses like a turkey baster to
suck in your blood. The average meal takes about 1 millionth of a gallon per
bite. Their saliva makes us itch.
Usually this minor annoyance can not be documented in terms of
economic loss, but, obviously, there may be some major economic losses, e.g.,
decreased recreation income and lower milk and beef production due to blood loss
and irritation. Occasionally extremely large numbers of mosquitoes can
actually cause the death of domestic animals through blood loss and anaphylactic
shock from reactions to mass injections of mosquito saliva. Mosquitoes are not strong flies- so fans easily blow them
away. The reproductive success
of mosquitoes depends in a large part on the ability of gravid females to locate
and select oviposition sites that will support the growth development of their
offspring. Enzymes diluted in water
create an adverse environmental condition that renders the water repellant
and/or lethal to all stages of growth.
Maintain tight screens and weather-stripping.
Use sodium vapor lamps or yellow non-attractive light bulbs
at outside entrances. Remove or empty frequently any containers that may hold rainwater (flower pots, tires, cans).
Clean out clogged roof gutters holding stagnant water. As a last resort, add light-weight oil or diluted
enzyme cleaner to surfaces of ponds, ditches and even animal hoof prints in mud where mosquitoes may breed.
Community effort is needed. Try the proper, professional use of entomopathogenic bacteria, e.g.,
Bacillus thurijngiensis strains (Bt) or Bacillus sphaericus
(Neide) (Bs), another important pathogen of mosquitoes, diluted enzyme
cleaners, dehumidifiers and/or fans and other Intelligent Pest Management® controls before spraying any volatile,
synthetic pesticide poisons.
Mosquito control agencies in the United States and Canada together send over $80 million
annually using very dangerous synthetic pesticide poisons that kill or injure non-target
species, e.g., people, pets and the beneficial creatures that feed on mosquitoes, to reduce simple mosquito annoyance. They are wasting
our money by attacking the adult populations which actually increase immediately after these toxins are sprayed.
Flight and biting activity increases over 500% on nights with a full moon. (The Asian tiger mosquito,
Aedes albopictus, is unusual in that it is active (biting) during the day- so bats, nighttime spraying and other
nocturnal controls are not very effective. Treat tires and other stagnant water with diluted enzymes.) The
mosquito's amazing whine is caused by the sound of their wings fluttering up to 600 times a second. A mosquito can
sense a person 20 feet away. In studies done on Sanibel Island, Florida, we consistently found the adult population
the day before the pesticide poison bombing was actually less than the day
after. The reason is simple - the mosquitoes can replenish faster than the natural predators, e.g., dragonflies, fish, frogs, nematodes, giant water
bugs, bats, spiders, birds, ants, backswimmers, snails, water scorpions and striders that feed on them can. In
addition, there are increases in tree pests because the adult mosquito pesticide poisons are broad spectrum killers that
kill the organisms that keep help forest pest population under natural control. Dehumidifiers, BT's, screens,
fans, caulking and personal care can provide far better and, obviously, safer control. In addition we still allow
entire wildlife food chains to survive. Proper Intelligent Pest Management® control includes the removal of all
stagnant water, the wise use of repellents and proper clothing, the use of fans, and the development of natural predators.
Remove the cause rather than treat the symptom.
While mosquitoes remain a major killer in other parts of
the world, in the United States, mosquitoes are simply not the scourge they once were. But they're still irritating,
they still bite us and there are some species in the United States that may still spread disease. Mosquitoes also
serve a vital ecological function. The larvae, pupae, and adults are important as food for fish, birds, bats, frogs,
and insects— an essential consideration when the subject of mosquito control arises. While there are more than
13 genera of mosquitoes in the United States, Most pest mosquitoes belong to one of three:
Aedes, Culex, or Anopheles.
Aedes mosquitoes are attracted to foot, sweat and skin odor more than
CO2, transmit dengue, yellow fever, encephalitis and West Nile virus and are more active during the day. They can not survive very long
during period of low humidity. Anopheles mosquitoes are more attracted to adult foot, sweat and skin odor than
CO2; they also are attracted to Limburger cheese; they prefer to feed indoors and they can transmit filariasis, and are
the primary transmitters of malaria. They are also more active at night. They are repelled by neem oils.
Culex mosquitoes are more attracted to
CO2 than skin odor and can transmit St. Louis encephalitis, filariasis and
West Nile virus. Mosquitoes that feed at night are more active during a full moon and are attracted to light traps.
Carbon dioxide (from your expired breath) will attract most mosquitoes and other biting flies up to a range of about
50 feet.The one thing that all mosquitoes require to complete their life cycle is water. If people could manage
all standing water, we would also manage all mosquitoes. While we can fill in a puddle, we don't want to fill in a
salt marsh. We can empty a bucket, but it's not so easy to empty a tire dump. Spray
Safe Solutions, Inc. Enzyme Cleaner in stagnant water you can not empty or drain and you will control these
pests, but remember you may also kill some beneficials.
These enzyme cleaners can remain active virtually
as long as they are wet.
ORDER
- Diptera (The true flies.)
FAMILIES
- Cuilicidae and Toxorhynchitinae
GENERA
- Aedes, Anopheles. Culex, Culiseta, Masonia and Psorophora
(Note: Toxorhynchitinae
female mosquitoes do not feed on blood like culicine female mosquitoes which do,
and contain the bulk of mosquito genera. There
are about 3,500 species and subspecies and at least 34 genera worldwide.
Canada has at least 74 species and the United States has over 169 species
belonging to 13 genera the most important genera include Aedes, Culex,
Culiseta, Psorophora and Mansonia .
(Michigan has more than 60 species of mosquitoes; Texas has at least 83
species.)
TYPE METAMORPHOSIS
- Complete
Egg
- Slender, oval, usually dark and
visible to the naked eye. Depending on the species, after each blood meal, females
produce 50 - 500 eggs in the first brood and usually fewer number of eggs in the
succeeding 8 - 10 broods. The
protein in animal blood produces the yolk in the fertilized eggs.
The egg-laying process can repeat itself every 3 days.
Anopheles eggs are laid singly; in the case of Culex
mosquitoes they are laid in clusters (rafts) in the mud or on the surface of
water or wherever water is likely to accumulate.
The mosquito eggs float until they are it is hatched in 2 - 6 days.
If optimum conditions persist for only a 2-month period, an initial
population of 1,000 female mosquitoes can grow into millions.
For every mosquito adult biting people there may be at lease 300 eggs
waiting to hatch. Mosquito eggs
can lie dormant for up to 7 years!
Larva
- They have a large head and thorax; legless with slender abdomens and look
“hairy”; up to 3/8" in length they are called “wigglers, wiggle tails
or wrigglers” and can be found in still, slow moving water feeding on small
organic debris, algae and microscopic life, e.g., protozoans.
Except for Anopheles larvae which rest horizontally on the surface
of the water and breathe directly through a hole in their abdomen - the rest are
in the water and a siphon tube on the abdomen is thrust into the air for oxygen.
This stage usually takes 4 - 10 days and
can include 4 larval instars. This
is the most vulnerable stage to attack mosquitoes - they are concentrated in
smaller areas. They sometimes go
cannibalistic and eat the smaller, newly hatched stages.
Larvae do not normally develop in water sources with a current, e.g.,
rivers and streams.
Pupa
- Found in water, it has a large combined head and thorax and slender abdomen,
giving it a comma shape. Swims actively. This
stage usually takes 5 - 10 days.
Adult
- Small and fragile, two winged with long, slender legs, capable of flying one
to several miles. A mosquito can fly up to 300 miles in its lifetime.
Some mosquitoes won’t go more than 500 feet from the larval habitat -
others can cover 6 - 8 miles a day with the help of the wind.
The female flies into a swarm of males and mating takes place almost
immediately in midair. Mating takes
from 4 to 40 seconds and some stay together for over an hour.
The Asian tiger mosquito was carried in a pile of scrap tires from either
Nagasaki or Kobe, Japan to Houston, Texas and now has spread to over 21 states.
Mosquitoes can only fly at 25 mph, but they can fly up, down, sideways
and backwards. Wings, legs and
other body parts are more less covered with tiny scales. Males have bushy feather-like antennae; females do not.
They smell with their antennae. Can
live from 10 - 60 days with females capable of living up to 5 months or more,
depending on predator pressures. Note:
They cannot fly into the wind, so simply sit in the breeze or install a fan
outside. Throughout the mosquito’s lifetime it can bite up to 6
times - even more if a blood meal is interrupted.
Only female mosquitoes bite. They
can sip up to 1-1/2 times their own weight in blood and still fly away.
They can sense a person 20 feet away.
They are attracted by carbon dioxide, odor, heat, moisture and wind;
activity peaks at down or dusk. Male
mosquitoes locate females by the sound of their wings in flight- the sounds
range from 500-800 vibrations a second. Males
will come to any source (e.g., a tuning fork)
that produces these sounds.
TYPICAL MOUTHPARTS
Larva -
Chewing.
Adult Female
- Piercing, cutting and sucking. Blood
protein is needed to produce eggs. If
she gets too bloated with your blood to fly, she literally releases a little
“piddle” from her bladder on you.
Adult Male
- Tube not fitted for piercing the skin; feeds only on flower nectar and fruit
juices. The male helps pollinate
flowers.
DISEASE ASPECTS
- Mosquito bites result in red swollen areas called wheals which itch severely.
Some people are highly allergic to the proteins injected by mosquitoes and are
ill for days. They are vectors of
malaria, yellow fever, dengue, canine heartworm and several
forms of filariasis and encephalitis.
Canine heartworm disease is a serious, deadly disease wherever mosquitoes
are present. Thousands of dogs each
year just in Michigan become permanently debilitated or die from lung, heart or
circulatory problems caused by heartworms.
Heartworms, the diameter of a tooth pick, can grow from 5" to
14" long. In advanced cases, 100 or more worms have been found in a single
heart.
LENGTH OF LIFE CYCLE
- Varies among species and climatic
conditions; usually about 2 - 9 weeks.
LIFE CYCLE-
Of the four life stages of the
mosquito—egg, larva, pupa, and adult—the adult is the only stage that
doesn’t exist in standing water. Males live 1-2 weeks, but females can live up to 2 months.
The female mosquito lays
her eggs on the water or, in the case of Aedes mosquitoes, above the
water in areas that are sheltered from waves and with sufficient organic matter
to feed the larvae. Eggs laid on
the water’s surface hatch in one to three days.
Eggs laid by Aedes mosquitoes above the water line remain dormant
until they are flooded.
The mosquito larvae or
“wigglers” that hatch must live in water to survive. They float at the surface breathing through an air tube and
filtering food material through their mouth brushes. When disturbed, the mosquito larvae dive towards the bottom
with a jerking motion. The larval
stage lasts from five days to several weeks depending on the species and on
environmental conditions such as water temperature.
The mosquito larvae
transform into pupae or “tumblers”. Although
the mosquito pupae don’t feed, they are quite active and may be seen breathing
at the surface or bobbing through the water.
Inside the pupal skin, the adult mosquito is developing and will emerge
in two to three days. Mosquitoes pass the winter either in the egg stage or as
adults.
FEEDING HABITS - Only
the female mosquito sucks blood, which she needs to lay eggs, but she feeds on
plant nectar for energy. Her
mouthparts have 6 long hollow needles; through one of the needles she drips
saliva into the wound to keep the blood from clotting as she sucks it up through
the other hollow needles. Adult
male mosquitoes feed only on plant nectar and are harmless to people.
Most female mosquitoes
feed during the last 2 hours of sunlight until just after dark and begin just
again before daylight. They spend
the daylight hours hiding and resting in dark, damp, cool areas.
Some mosquito species, however, feed during the day and others feed
during both day and night.
The mosquito's blood-sucking habit is what causes certain species of mosquitoes to be disease vectors. If a female mosquito sucks blood from
a person infected with malaria, for instance, the disease organisms can survive and reproduce in the mosquito, ending up in her salivary glands.
When
she next feeds on a host, she inoculates her new victim with the disease.
Larval mosquitoes feed on organic debris (with the exception of a few species that are predators). They use a pair of mouth brushes to strain
out small aquatic organisms and particles of plant and animal material
present
in the water. Note: Enzyme cleaners with protease will help "eat"
the organic debris.
HABITAT
- Mosquito eggs, larvae and pupae are found in undisturbed, slow moving or
stagnant water. Adults normally
stay in protected, secluded places during the day.
They become active and bite late in the afternoon and during the early
evening and morning hours when the wind is calm.
Mosquitoes are most prevalent in moist, wooded or lowland areas.
Eliminate water habitats and you control mosquitoes!
NATURE OF INJURY
- Mosquitoes are persistent biters of all warm blooded animals and some
cold-blooded creatures, e.g., frogs and snakes.
They individually consume about 2 - 8 milligrams of blood per meal.
Aside from irritating bites, a number of species transmit diseases and
have caused allergic reactions and even death. Aedes aegypti is worldwide in distribution; carries urban
yellow fever and the only known vector of Dengue in the New World.
The malarial parasite carried by mosquitoes probably kills a million
people in Africa each year. Malaria claims 2-7 million lives throughout the world
annually. Mosquitoes also carry
yellow fever and at least 100 different viruses - these diseases adversely
affect at least 800 million people every year.
The Anopheles mosquito, for instance, carries malaria, and several
species including Culex, the common house mosquito that stings before she
bites, transport encephalitis-causing viruses.
You can sample/collect with biting or landing counts.
Seasonal Abundance.
Mosquitoes may breed and
develop any time from the beginning of spring to the first hard frost of fall.
In general, populations are highest in summer and early fall.
There may be from one to several generations of mosquitoes during a
season depending on the species, the temperature, and the amount of rainfall.
When rainfall is abundant,
many mosquito species can lay eggs continuously. Under ideal conditions with high temperatures, development
can be completed in less than a week, resulting in large populations of flying
adults. We do not suggest you use
DEET, not only do we believe this product is dangerous - the repellent only
works after the mosquito lands on treated skin, it gets confused and
forgets what they were going to do and fly away - if you forget a patch of skin
they will find it right away.
Medical Importance.
Worldwide, mosquitoes transmit
many debilitating and fatal diseases, especially in tropical, developing
countries. The most important of
these is malaria, which has been on the increase in the last decade.
The Centers for Disease Control and Prevention and the World Health
Organization both report that currently available treatments for yellow fever
and malaria are failing. In the
United States, most mosquitoes are primarily an annoyance, causing itching bites
and welts that can become secondarily infected.
Human mosquito-transmitted diseases remain relatively rare, due largely
to modern pest control methods and disease detection.
Encephalitis, among humans, and dog heartworm, among dogs, are the
main diseases transmitted by mosquitoes in the United States.
Pregnant women attract mosquito attacks more than anyone.
Malaria. As
mosquitoes become more and more resistant to insecticides each year, new control
strategies are sorely needed. Researchers
at the Johns Hopkins School of Public Health have identified a protein in the
salivary glands of the female Anopheles gambiae mosquito - the primary carrier
in Africa - that appears to help Plasmodium recognize and gain entrance to that
mosquito’s salivary gland. The
Author believes that his patent pending use of protease enzymes will help
destroy this protein.
Encephalitis.
At least six types of mosquito-transmitted encephalitis occur in the
United States. These are Eastern
equine encephalitis, Western equine encephalitis, California encephalitis, St.
Louis encephalitis, Venezuelan equine encephalitis, and La Crosse encephalitis.
Each type is caused by a different virus or virus complex affecting the
central nervous system. Symptoms of EEE in horses include fever, impaired vision,
irregular gait, reduced reflexes, inability to swallow, convulsion and death.
These viruses are normally transmitted by mosquitoes from birds or small
mammals. Occasionally horses or
humans are infected. Despite the
small number of people infected annually by eastern equine encephalitis, it is
considered a serious disease because it is often fatal.
Vaccinating horses properly will prevent them from contracting Eastern
equine encephalitis.
Dog heartworm.
This is a filarial parasitic
disease transmitted by a number of different mosquitoes to dogs and, rarely,
man. Once a problem only in the U.
S. coastal areas, dog heartworm is now found in every state in the United
States. The nematodes, which lodge
and grow in the heart tissue, can be fatal to dogs if left untreated.
There has been some
concern about whether mosquitoes are capable of transmitting AIDS
from an infected person to an uninfected person. Unlike encephalitis viruses and
other mosquito-transmitted (viral) diseases, the HIV virus that causes AIDS is
supposedly not able to survive inside the body of the mosquito.
However, the American cockroach and ticks in Africa have already been
implicated in the spread of HIV.
MONITORING AND
THRESHOLDS
Introduction
Mosquito sampling and
counting the mosquito population accomplishes a number of things.
It helps determine whether mosquito control is necessary.
It determines what growth stage the mosquitoes are in, providing
information necessary to properly time control methods.
It tells which mosquito species are present, especially important in
areas of disease outbreaks. Finally,
it helps to gauge how effective control efforts have been and when they need to
be employed again.
Mosquito sampling should
be done at least once a week, and more often during peak season.
It is important to consistently sample the same sites each time.
The numbers counted, the growth stage, and the species and sex should be
needed when possible. All of this
information gives an estimate of the population and must be compared with
previous counts to determine whether the number of mosquitoes are increasing or
decreasing. You can make an
estimate of the number of mosquitoes in an area by counts of larvae or adults or
both.
Larval Dipper Counts
Mosquito larval dippers can be purchased through biological supply houses or you can make your own. It
is basically a shallow, plastic, enamel, or aluminum cup attached to a long handle. To collect floating
mosquito larvae, pupae, depress one end of the dipper under the surface and quickly but smoothly scoop up larvae. If
you move too quickly or cast a shadow over the surface, they will dive to the bottom. The number of dips at each
site will vary according to the size of the water body, but generally are in multiples of ten. Take five dips from open
water and five from the water's edge, near vegetation if possible. Dipper instructions should be made weekly
during breeding season. Larvae can also breed in rainwater that has collected in containers such as eavestroughs,
toys, buckets, garbage cans, canoes, tires, and animal watering troughs. To sample larvae in less accessible
areas such as tree holes, use a large basting syringe to collect them. Empty them into a white pan for counting
to mosquito larvae. One advantage to sampling larvae is that the problem can be treated with
Safe Solutions, Inc.'s Enzyme Cleaner at the same time it is identified. When counting adult mosquitoes, the mosquitoes can be flying in from
some distance away.
Adult Trapping
Trapping of adult
mosquitoes gives information on the relative population size and the species
composition. Light traps are very
helpful for monitoring certain species of mosquitoes. Not all mosquito species are attracted to lights, e.g.,
Anopheles and Aedes. Different
models of traps vary in the numbers, the species, and the proportion of males to
females that they each attract and catch. New
Jersey light traps with a frosted 25 watt bulb and CDC light traps (and their
variations) are the traps most commonly used.
Light traps are operated from dusk to dawn, powered either by electric
line or a battery. Some traps are
available with a photoelectric cell that turns the light on at dusk and off at
dawn. When mosquitoes approach the
light, they are blown by a small fan down through a funnel into a killing bag or
jar. The light mosquito trap should
be hung about 6' off the ground in an open area near trees or shrubs but away
from competing lights and buildings. Traps
should be emptied each morning and the catch stored in a labeled box until it
can be sorted and identified.
Since mosquitoes are
attracted to carbon dioxide in the host’s breath, some light traps are
augmented with a one pound block of dry ice, wrapped in newspaper and hung next
to the trap. The addition of dry
ice also allows sampling on moonlit nights or in areas where bright lights may
conflict with the light trap. And
it allows daytime sampling of species that are active during the day or that are
not attracted to lights. Other
traps include sweep nets and large drop nets of various designs.
Because some mosquito
species are not attracted to light traps they should be used in conjunction with
other kinds of sampling methods. Monitoring
for adult mosquitoes is an important part of the management of some
mosquito-vectored diseases such as eastern equine encephalitis.
The decision to use pesticides for mosquito suppression should be made only
after intensive monitoring of the mosquito population in an area to determine if
the species that actually vectors the disease to humans or horses is
present. The incidence of the
disease in the wild animal population (or in caged chickens) is monitored as a
way to estimate the possibility of transmission to humans or horses. Education
is also emphasized to alert people to the presence of the disease and how to go
about protecting themselves.
Resting Stations
Adults of many species are
inactive during the day and rest quietly in cool, dark and damp places.
Daytime collections made at these sites give a good indication of the
species of mosquitoes present in the area.
Adult Landing/Biting
Counts
Collecting mosquitoes as
they land on you or an animal to bite is a convenient method of sampling biting
populations. It simply involves
rolling up a sleeve or pants leg or exposing your back and sitting quietly for a
designated period of time, usually 10 minutes.
During that time, each mosquito that lands on the leg or arm or back is
collected with a battery or mouth-operated aspirator. It is important that you collect each landing mosquito for
counting and identification and to ensure that you don’t count the same
individual again. Mosquito biting
counts are best conducted from 30 minutes before sunset to 30 minutes after
sunset (unless sampling day-biting species) by the same person each time.
The advantage to using
landing counts as a mosquito sampling device is that you are counting only the
biting (female) mosquitoes. The
method does not collect male mosquitoes or species that do not actively bite
people. It can also be used to
count and collect daytime biters.
When sampling adult
mosquitoes, sample any and all areas where mosquitoes may be a nuisance.
Obviously, you should sample areas from which you have received
complaints and near areas with high larval or pupal counts.
Sample the same sites regularly, from one to seven nights a week.
Adult mosquito information is most useful in gauging the extent of your
mosquito problem, since it is only the adults which transmit disease or create a
nuisance.
Threshold/Action
Population Level
The data from mosquito
sampling and monitoring will be used to help decide at which mosquito
infestation level to initiate management tactics. This decision level may be based on larval and/or adult
counts, mosquito complaints from visitors, residents, students, patients, etc.
the potential for disease outbreaks, and the risk of the management tactics to
other animals. For instance, in an
area where there have been actual reported encephalitis cases, the risk is
higher and the action level will, obviously, be lower than in other cases.
The number and location of
mosquito complaints should be plotted on a graph against the counts of immatures
adults for the same date and site. The
amount of unacceptable complaints is the injury level.
The graph should show the number of mosquitoes that correspond to the
complaint injury level. This is
your action level.
Action levels will,
obviously, be different for each situation.
In some areas, general annoyance does not occur until the number of
female mosquitoes caught in light traps exceeds 25 per night.
Other action levels that have been used are landing rates averaging more
than 5 mosquitoes in 10 minutes and dipper counts averaging 5 larvae per dip or
the outbreak of disease.
HARBORAGE POINTS
- Young mosquito stages breed in any available water.
Mosquitoes may be found in birdbaths, blocked rain gutters, rain barrels,
buckets, old tires, bottles, dishes, tin cans, jars, cisterns, watering cans,
toys, carts, hollow stumps or trees, plastic wading pools, septic tanks, air
conditioner drain outlets, utility meters, wheelbarrows, ponds, over irrigated
lawns, cesspools, watering troughs, drainage ditches, mud puddles, flower vases,
potted plant saucers, unused toilets, hoof
prints, water softening tanks, wells, on flat roofs and any other place where
undisturbed or stagnant water can
collect. At night, like vampires,
the adults emerge from breeding sites and fly to areas of human and animal
habitation to obtain blood. During
the day most adults remain secluded in such places as trees, outbuildings,
shrubbery, cars and homes. Eliminate
cool, dark, damp areas. Wash/fog/spray infested areas with diluted
Safe Solutions, Inc.
Enzyme Cleaner.
INTELLIGENT PEST
MANAGEMENT® CONTROL - First of all,
identify the pest mosquito species then establish a quantity tolerance or
acceptable injury levels. Remember
to keep all screens in good repair. Mosquitoes
have become resistant to many insecticide poisons. Cover all flues and chimneys, especially during the
summer months. Eliminate resting
places such as tall grass, weeds, shrubbery and vines from around the buildings.
Eliminate rainwater-collecting items such as old tires, pans, cans,
buckets, etc. Never kill any
dragonflies or damselflies who both eat lots of mosquito larvae and adults.
At least once a week, drain or treat plastic swimming pools and
birdbaths. Provide for proper water
drainage around the foundation of the building.
When visiting mosquito-infested areas, wear protective clothing to
prevent bites. If small garden
ponds are present, use fish (Gambusia sp. or others), or treat ponds with
Bacillus thuringiensis israeliensis or
or diluted enzyme cleaner as a safe and effective
alternative.
The key factor in a
mosquito intelligent pest management® program is determining whether or not
control is necessary. This decision
requires a regular mosquito sampling program to determine what species are
present and in what numbers, and a set of action thresholds to determine if
management tactics are necessary. If
control is needed, then decisions have to be made on the best combination of
tactics to suppress the mosquito population while affecting the environment as
little as possible. You can always
swat them, but often you create a breeze with your intended blow that blows them
away. If you lightly pinch your
skin on either side, the pressure
will trap her stinger inside and even when her sensors tell her to stop,
she’ll continue to take in blood until she literally explodes.
Normally, source
reduction—eliminating or altering the water so that the mosquitoes cannot
breed or complete their life cycle—is the first choice for control.
If source reduction is impossible or incomplete, the next tactic to
consider should be biological control of the larvae with predators, bacterial
insecticides, or growth regulators. Measures
that increase water circulation like the Clean-Flo® system and vegetation
removal or altering water circulation patterns may reduce mosquito breeding.
Interpretive displays (education) can be used to explain the role of
mosquitoes as a food source for animals such as bats, birds, fish, and to help
people understand that not all mosquitoes bite or carry disease and so all
mosquitoes do not need to be killed. Personal
protection through the use of proper clothing and mosquito repellents and fans
can be explained, as well as the avoidance of areas with high mosquito
populations.
Source Reduction
The simple fact that all mosquito species require water and aquatic vegetation to develop is the
obvious key to their control. No standing water means no mosquitoes. Aquatic vegetation offers mosquito larvae
and pupae protection form wave action and natural predators. Source reduction is the first step in an intelligent
pest management® program for mosquitoes. It is simply the use of mechanical methods to eliminate standing water.
Source reduction involves filling, deepening, draining, ditching, managing water levels, maintaining
shorelines, managing aquatic and inundated vegetation, and others. While these methods may prove to be more extensive
and more expensive than some other controls, in most cases they need be done only once. Unfortunately,
these methods will most likely require permitting from several agencies before they can be implemented. They are
also not feasible in natural zones. Look in the water to see the "wigglers" (larvae) and "tumblers" (pupae) that
indicate mosquitoes are breeding in the water then add enzyme cleaner or Not Nice to Bugs™ and see your
mosquito population in or out of the water disappear.
Source reduction controls
the immature mosquito stages—eggs, larvae and pupae. Because these stages are concentrated in discreet bodies of
water, they are much easier to control than are dispersed adult mosquitoes.
Two water management tactics are ditching and ponding.
That these would only be allowed in a developed zone. Ditching controls mosquitoes in two ways.
In some cases water drains out of the potential breeding sites.
In others, ditching allows fish access to the isolated pools where they
prey upon the larvae and pupae. Ponding
is another water management tactic that turns a temporary pool breeding
mosquitoes into a permanent one capable of supporting fish and other mosquito
predators. Ponding is accomplished
by raising water level, digging new pools, or through impoundment.
If standing water can't be completely eliminated, control of mosquito larvae in the water is the next step. This
is best done with natural controls such as mosquito fish or biorational insecticides. The latter do not affect pupae
and should not be used if this is the predominant life stage. You can use Safe Solutions, Inc. Enzyme Cleaner at any stage to gain immediate control.
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