الفهرس 
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Abstract
The present work aims to study some factors governing
the vectorial potentiality of Culex pipiens in human
filaria transmission. The vector used in this study
was collected from a filarious endemic area (El-Kashish
village, Qalyubiya Governorate). The present study revealed
the following:
A. Selection of susceptible and refractory strains:
High susceptibility and refractoriness were achieved
in the selection of Culex pipiens to filarial parasite
(Wuchereria bancrofti). The first trial of selection
was controlled by brother-sister mating which led to
the appearance of lethal
selected groups at the 9
genes
th
and termination of the
generation. Accordingly,
a cousin-cousin mating method of selection was used in
the second trial to avoid accumulation of the deleterious
genes. The selection of susceptible and refractory groups
in the 2 nd trial was started only with one female mother
to minimize the genetic variations and to achieve quIck
almost homozygous susceptible and refractory strains.
According to the same reason, one male was mated with
twelve virgin females.
The extrinsic incubation period for development
of filarial parasite resulted from our experiments was
found to be 12 days post-infection at 27 ± 2° c.
The deleterious genes were accumulated as a result
of repeated full sib-mating in the first trial of selection.
Accumulation of these genes resulted in high pupal
mortality and a limited number of survived adults. Viability,
fecundity and longevity of these adults were substantially
reduced. In addition, it was observed that some
of the emerged adults had deformations which cause their
death after few days of emergence. All these effects,
led to the loss of the selected susceptible and refractory
groups. It is clear that the survival rates in the refractory
group were less than that in the susceptible
one.
B. Experimental human filaria transmission ~Y Cx. pipiens
using capillary feeding technigue:
The capillary feeding technique used by Aitken (1977)
for demonstrating virus transmission was modified and
used for studing the transmission of filarial parasite
by Culex pipiens. By using this technique, the infective
females could be separated into two groups; Transmitters
and non-transmitters. The capillary feeding technique,
provides an easy rapid method to assess parasite transmission
by infected mosquitoes under laboratory conditions.
Also, by using this technique, the ability of transmitter
females to eject L3 larvae can be determined. Transmission
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experiments carried out by this technique showed that
the period of transmission of infective stage larvae
(L3) by Cx. pipiens in the two trials of selection is
13 days post-infection.
By using the capillary feeding technique, it was
indicated that a high number of the non-transmitter
females harboured L3 larvae in their proboscis. This
demonstrates that not all mosquitoes harbouring L
3
larvae
are able to eject them during feeding I,e.: not every
infective female is capable of ejecting L
3
during feeding
and hence, is not able to infect man under experimental
conditions. In the transmitter females of Cx. pipiens,
it was indicated that the number of ejected larvae are
more or less lower than the non-ejected ones.
c. Mode of inheritance of susceptibility and refractoriness
of Cx. pipiens to w. bancrofti:
According to the achieved results it may be concluded
that, inheritance of susceptibility of Cx. pipiens to
w. bancrofti is controlled by a sex-linked incompletely
dominant gene.
D. Evaluation of the influence of different media on the
ejection of infective larvae (L
3
1i
The most preferred medium which could stimulate
the ejection of infective larvae from the mosquito vectors
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was found to be the sweat followed by a mixture of sweat
and blood. The thrid medium was a mixture of sugar solution
and blood followed by blood then sugar solution
and lastely water. In air medium, a fluid free from any
L3 larvae was ejected.
E. Biochemical differentiation between susceptible and
refractory groups of Cx. pipiens to w. bancrofti
parasite:
1. characterization of enzymes:
No consistent differences between the two strains
have been detected by
dehydrogenase, Esterase,
enzymes.
the study of a-Glycerophosphate
Malate dehydrogenase and Malic
Experiments on Aldehyde oxidase enzyme, it was found
that the bands of susceptible specimens resulted by starch
gel electrophoresis were concentrated while in refractory
ones, some bands were absent and the others were very
faint. This observation may indicate a higher Aldehyde
oxidase activity in the susceptible strain.
2. characterization of protein subunits:
There are several specific proteins for the susceptible
group, others for the refractory one and some proteins
are common in the two groups. In each group, there is
a specific protein repeated in all generations. The molec-
154 -
ular weight of this protein in the susceptible group
is 110,000 dalton while in the refractory group, it is
120,000 dalton. These specific proteins may be responsible
for susceptibility and refractoriness of ex. pipiens to w.
bancrofti parasite.