Cotton aphid, Aphis
gossypii and whiteflies, Bemisia tabaci are an important pests in
cotton plants in Egypt.
The present work was conducted during two successive seasons 2014 and 2015 in Beni- suef Governorate on the cotton crop by spraying the tested insecticides
alone and mixtures of  both acetamiprid
and thiamethoxam with chloropyrifos to estimate the percentage of reduction of Aphis
gossypii and Bemisia tabaci and their associated predators, Coccinella  septempunctataand Chrysoperla
carnea,after different intervals which include (24 hours) to estimate the
immediate effect, as well as after 3 ,7 and 14 days to evaluate the latent
effect. Results indicated that acetamiprid, thiamethoxam and chloropyrifos
alone proved to reduce Aphis gossypii and Bemisia tabaci populations up to 14
days after treatment throughout both seasons. Whereas, combination of
acetamiprid and thiamethoxam with chloropyrifos at half recommended rate showed
the high efficiency with reduction percentage reached to 100.0% at same exposure
time during the successive seasons 2014 and 2015. In addition, acetamiprid,
thiamethoxam and chloropyrifos proved the high reduction percent to the
populations of Coccinella septempunctata and C. carnea when these insecticides were used
alone at recommended rate at 24h from treatments. Chlorpyrifos in mixtures with both acetamiprid, and thiamethoxam at
half recommended rate showed the high effect with reduction percentage reached
to 100.0% reductions for both predators in two seasons. Results suggested that,
choosing suitable insecticide to control the tested cotton pests not only
depends on its efficiency but also its toxicity to
natural enemies. Also, these results indicated
that the initial kill and residual effect of these insecticides was
highly persistent up to 14 days. The overall results appeared promising in
combination with insecticides as result of significant increasing its reduction
percent.