Mosquito surveys
of two urban localities in Cairo
(El-Muqattam and Abu-Seir) were undertaken for one year. The extent of
interspecific association between the two common species: Culex pipiens
and Cx. perexiguus was measured on the basis of presence-absence
data and on their relative numbers.  The
two species had a significantly slight/ moderate association (C=
0.19-0.35 and C_AB= 0.50-0.54, P˂0.001). The values of Sorensen's coefficient (I)
indicated high association in El-Muqattam (0.88) and moderate association in
Abu-Seir (0.47) or the two localities altogether (0.53).  Such coefficient showed monthly variation and
was directly related to the separate/ compiled densities of the two species (b=
0.01-0.02) in El-Muqattam (P˃0.05),
Abu-Seir and the two localities (P˂0.05).
The obtained results indicate that the requirements of the two species are
similar and that their larval densities influencing the degrees of their
interspecific association.