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Forty-nine native species and one
recently introduced species of mosquitoes have been
observed in Suffolk County, Long Island, New York, and
are assumed to be resident in 2004. Fifteen
of these species impact the quality of life or are
disease vectors. Following is a discussion of mosquito:
Reproduction
Development
Feeding
Transmission of Disease
Species of Mosquito
in Suffolk County
For detailed information
see Task 3 - Literature Review (Book1)
One way to classify mosquitoes is by their mode of
reproduction. Mosquitoes that breed in a similar manner
frequently have other similarities, such as their larval
lifestyles. Because control measures are best directed
at the larval stage these groupings can have practical
applications.
Some species reproduce once a year (univoltine), while
others lay eggs that hatch at various times throughout
the year (multivoltine). All mosquitoes require damp
to wet conditions to lay their eggs. Some mosquitoes
require that their eggs remain in water, whereas, desiccation
tolerant mosquitoes require that their eggs dry out
prior to further development. Desiccation tolerant mosquitoes
tend to hatch in “broods,” as environmental
conditions result in eggs developing at approximately
the same time. Desiccation intolerant mosquitoes may
not hatch at one discrete time, but rather in a more
diffuse manner. Some mosquitoes need organically polluted
water as breeding sites, and others can tolerate or
need salt water. Some mosquitoes overwinter as adults,
but others overwinter as eggs or larvae.
All mosquitoes follow the same developmental
pattern. After hatching from an egg, each individual
lives in an aquatic environment as an air-breathing larva,
and undergoes metamorphosis through four stages (instars)
prior to becoming a non-feeding pupa. After the pupal
stage, a fully developed adult emerges.
Mosquito Life Cycle (from a publication of the New York
City Department of Health)
Males and females tend to feed on plant nectars to fulfill
daily energy needs; however, in almost all mosquito species
the female requires a blood meal for her eggs to mature.
Most species have general preferences of prey for blood
(such as warm or cold-blooded animals), and some preferences
are quite specific (so much so that Anopheles gambiae,
the primary African vector of malaria, almost exclusively
feeds on people).
Female mosquitoes can transmit diseases to humans when
they bite to obtain a blood meal. Mosquitoes are considered
to be disease vectors because they can transmit diseases,
via a blood meal, from an infected host to a human target.
The first blood meal transmits the disease-bearing organism
to the mosquito (usually, the mosquito is not affected
by the disease), and the second results in its transfer
to a new organism. Mosquitoes use secretions of various
kinds to prevent blood clotting and make the target
organism less aware of a bite and the feeding process.
Diseases are transmitted in the injected secretions.
Thus, diseases can only be spread when a mosquito feeds
for a second time. Particular diseases are transmitted
by various aspects of the feeding process, in that some
viruses or parasites are associated with secretions
released early in the meal, and others are associated
with secretions released at other stages.
Birds and other animals are the primary carriers of
arboviruses (viral diseases transmitted by arthropods),
such as Eastern Equine Encephalitis (EEE) or West Nile
virus (WNV), while humans are the primary carriers of
arboviruses, such as yellow fever and malaria. The arbovirus
is transferred from a primary carrier or host (i.e.,
birds or humans) to the mosquito and, finally, it is
transferred to the recipient or terminal host (i.e.,
humans). In this chain of events the mosquito is often
referred to as the bridge vector. The behavior of particular
mosquitoes determines their capacity as vectors, and
their ability to upset human lifestyles through aggressive
biting. In addition, their developmental biology also
determines how they can be controlled.
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Integrated Mosquito Management
