الفهرس 
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Abstract
The aim of this study was to investigate the efficiency offour pesticides againstthewhitefly, Bemisiatabaci,infesting squashplants during the two growing season,2017 and 2018, under field conditions. Survey and seasonal abundance of predators associated with B. tabaci were also conducted
Concerning the survey and seasonal abundance of predators associated withB. tabaci infesting squash plants, experiments were carried out during two successive seasons (2017 and 2018) at EL-Ibrahimiya,Sharkia governorate. Data obtained indicated that four predaceous insect species belonging to two families and two orders were surveyed on B. tabaci infesting squash plants, namly: Coccinella septempunctata L., Coccinella undecimpunctata L., Scymnus interruptus (Goeze) and chrysoperla carnea (Stephens). As species C.septempunctata and S. interruptus were the most predominant followed by C. carnea.
Regading the insecticidal activity used, results reveald that the mean effect of the reduction percentages of the whitefly, B. tabacipopulations on squash plant during season 2017caused by Lambda cyhalothrin, Thiamethoxam, Azadirachtinand Biovarwere 86, 81.5, 72,25 and 86.66% respectively, While, the initial reduction percentages for these pesticides were 98, 96, 93 and-%, respectively. The general mean percentages of reduction caused by Lambda cyhalothrin, Thiamethoxam, Azadirachtinand Biovar were 92, 88.75, 82.63 and 90.33%, respectively. So the efficiency of thetested pesticides on whitefly could be arranged according to their percentages of reduction in infestation asfollows: Lambda cyhalothrin > Biovar > Thiamethoxam > Azadirachtin, respectively.
Regarding season 2018, data toke the same trend as mentioned befor, however the general effect of these pesticides were 95.25, 92.75, 88.38 and 92.67, respectively, for Lambda cyhalothrin, Thiamethoxam, Azadirachtinand Biovar, respectively.
Lambda cyhalothrinand Thiamethoxam were used by the recommended rate, which were (1 lit / fedd.) on squash plants. The residues were determined after 1, 3 and 7 post treatments.
The residual effects were determined on leaves, washed fruits and unwashed fruits. However the amount of these residues were as follows: 5.7, 3.2 and 6.5; 1.8, 0.8 and 3.1; 0.29, 0.04 and 0.37 for Lambda cyhalothrin. while, the residual effects were 4.6, 2.4 and 4.9; 1.2, 0.55 and 1.8 ; 0.18, 0.026 and 0.17 for Thiamethoxam.So we can use these pesticides after 3 days post-treatment which was at the range of Maximum residue limit(MRL).