Mosquitos are Wonderful

This discussion topic submitted by Richelle Schrock (Schrocrd@po.miamioh.edu) on 4/9/98.

Richelle Schrock

Mosquitos are remarkable life organisms. There are almost no places on the earth that are not inhibited by mosquitos at one time or another during the year. They are mostly seen as a nuisance by most people, but they are an organism that represents the perfection of living beings. I plan to teach the class about the growth cycle of mosquitos, what and when they eat, why they are attracted to humans, and their part in the transmission of malaria.

I. Introduction
A.There are 2500 or so species of mosquitos known at present, they are arranged in 33 genera
B.Most of the genera are found in tropics, Central and South America have about 700 species living there
C.Mosquitos belong to order of two winged flies known as Diptera
D.Mosquitos belong to suborder Nematocera
E.Belong to family Culicidae which are divided into three subfamilies
1.Anophelinae-many species of which are responsible for transmission of malaria.
2.Toxorhynchitnae-enormous larvae that eat other mosquito larvae
3.Culcinae

II. Mosquito Eggs
A.Found in a variety of different habitats
1.small pools
2.large marshes
3.rock pools, etc.
B.Some mosquitos lay eggs singly, others lay them in masses attached to floating vegetation

III.Larval Growth
A.Lasts five to six days
B.The head grows and the neck becomes thick
C.Thorax and abdomen grow
D.Size of larvae affected by temperature
1.Rapid development at high temperatures leads to production of small individuals
2.Slow development at low temperatures leads to production of large individuals
3.Most larvae will not reach maturity in abscense of light, although there are a couple of types of mosquitos that will develop in complete darkness
E.Mosquito larvae are filter feeders
1.On either side of the mouth is a brush-like structure of about 1,000 curved hairs
2.When larvae are feeding the bristles move in rhythmic sweeping fashion

IV.Adults
A.If mosquitos are well fed as larvae they have sufficient reserves to last them through the pupal period and first few days of adulthood
B.For first few days they rest up from the sun, rain, and wind
C.Then they take their first meals from flowers usually at sunrise or sunset
D.Some mosquitos feed only on nectar and other sources of sugar
E.Proboscis is the mosquito snout for sucking
F.Skin or flowers are pierced by a fascicle which allows access to blood through skin or nectar from flowers
G.While all mosquitos, both male and female feed on sugar in one form or another, most females require a blood meal as well if they are to produce any eggs

V.Why and When are mosquitos attracted to us
A.Mosquitos are attracted to warm and moist objects
B.humans breathe out warm and moist are, so your breath is what attracts mosquitos to you
C.Most mosquitos feed after dark, there are some species who feed during the day, but in the tropics most feed at night
D.Anopheles funeslus, one of the two important malaria transmitters in Africa, starts to become active around midnight onwards and shows and sudden escalation of feeding activity shortly before dawn

VI.Mosquitos and Malaria
A.In nature malaria can only be contracted via the mosquito
B.Malaria parasites injected into bloodstream by an infected mosquito and then goes to liver and multiplies
C.The period between the original infection and the appearance of parasites in the bloodstream is about six to ten days
D.Once in the bloodstream the malaria parasites muliply in the red blood cells via asexual reproduction

VII.Excerpt from poem about mosquitos
A.Yet what an aura surrounds you;
Your evil little aura, prowling, and casting numbness on my mind
That is your trick, your bit of filthy magic:
Invisibility, and the anaesthetic power
To deaden my attention in your direction.

But I know your game now, streaky sorcerer.
Queer, how you stalk and prowl the air
In circles and evasions, enveloping me,
Ghoul on wings
Winged Victory.
J.D. Gillett

sources:
Mosquitos, J.D. Gillett. Weindenfeld and Nicolson,1971.

A Catalog of the Mosquitos of the World, Knight Stone. The Thomas Say Foundation, 1977.

Physiology of Mosquitos, A.N. Clements. A Pergamon Press Book, 1963.

Mosquito Ecology, M.W. Service. John Wiley and Sons, 1976.



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