Impact of  abiotic (minimum–maximum temperatures and
relative humidity) and biotic factors ( Coccinella undecimpunctata,  Syrphus corollae , Amblyseius swirskii, Nesidiocoris
tenuis  and Chrysoperla carnea)  on the population dynamics
of Bemisia
tabaci (Genn.) and Tetranchys urticae (Koch) infesting tomato plant Lycopersicon
esculentum L. at kafr El sheikh
governorate, Egypt were studied on spring plantation of  2016 &2017 seasons. The analysis of
variance revealed significant variation among dates of observations, lines and
in their interaction for B. tabaci
(Genn.), T. urticae (Koch) and their natural enemies. The mean number of
B. tabaci and T. urticae
during the first season was higher than that was recorded during the second
season. The percentage of explained variance (E.V.) of abiotic and
biotic altogether in the population densities of  B.
tabaci and T. urticae in the first season was stronger percentage
values than second as (62% - 86%) and (94% - 77%)  for eggs and nymphs
of  B.
tabaci  while  (84% _ 77%)  and  (84% -98%)  and for eggs and movable stages of T.
urticae during spring of plantation 2016 &2017 seasons, respectively.