Efficacy Of Some Pesticides Against Piercing-Sucking Pests and Associated Predators on Cucumis sativus (L.) and Cucumis melo var. flexuosus (L.) Plants in Sharkia Province, Egypt.

            Field experiments were conducted in the Shubak-Basta village Sharkia province, Egypt on the Cucumber, (Cucumis sativus L.) and Cucumis, (Cucumis melo var. flexuosus L.) to study the effect of pesticides  i.e. (Thiamethoxam, Melbimectine and Pyredaben) against the piercing-sucking pests encompass; (the aphids, Aphis gossypii Glov., the thrips, Thrips tabaci Lind., whitefly, Bemisia tabaci Genn., the leafhoppers, Empoasca spp., the green stink bug, Nezara veredula L. in addition to the spider mite, Tetranychus spp. and side effects against associated predators ladybird beetle, Coccinella  spp., aphid lion, Chrysoperla  carnea  Steph. and true spiders during 2017 and 2018 seasons. The results revealed that the tested compounds recorded the high initial reduction 100.00% in all the tested pests on Cucumber and Cucumis plants. Thiamethoxam compound (1^st spray) was more effective on the T. tabaci, Empoasca spp., A. gossypii and Tetranychus spp. during the two seasons on Cucumber and Cucumis plants while, the Melbimectine compound (2^nd spray) was more effective on all treated pests as the initial effect in Cucumber and Cucumis plants, while the high annual mean reduction was varied in values according to the crop and pest tested during the two seasons. It was also found that the Pyridabin compound (3^rd spray) had a significant impact on the tested pests and on the two crops. In the case of the effect on predators, the results showed that 1^st spray, 2^nd spray and 3^rd spray of the tested compounds caused had a significant effect on associated predators. The annual mean reduction was 97.35, 75.95% for thrips and leafhoppers in the 1^st and 2^nd spray and 100.00% for the whitefly and leaf hoppers in the 3^rd spray on the Cucumber plants while in the Cucumis plants had the highest annual mean reduction of the tested pesticides 74.82, 65.76% on the aphids and whitefly insects in the 1^st and 2^nd spray and 100.00% on leafhoppers in the 3^rd spray in 2017 season.  The results showed that the annual mean reduction of the three sprays was 100.00% in the 1^st spray on the green stink bug and 100.00 % in the 2^nd spray on the aphids, third, leafhoppers and mites while in the 3^rd spray, the highest annual mean reduction of 89.78% in the 2018 season on the thrips in Cucumber plants. In the case of the effect of three sprays on insect piercing-sucking pests in the Cucumis plants, the highest annual mean reduction was 92.04, 100.00 and 65.97% for the three spray on the thrips. The seasonal mean of the three sprayers on the Cucumber plants caused the highest percentage of the decrease in the number of piercing-sucking pests where it was 78.98, 78.24 and 73.85% on the thrips, leafhoppers and whiteflies in 2017 season. In the 2018 season, the highest seasonal mean of the three sprayers recorded on the Cucumis plants were 74.82, 72.18 and 66.13% on the aphids, leafhoppers and whitefly numbers in 2017 season. But in 2018 season the seasonal mean of the three sprayers on the Cucumber plants caused the highest percentage of the decrease in the number of piercing-sucking pests where it was 100.00, 96.33, 86.58, 84.99 and 76.69% on green stink bug, leafhoppers, thrips and mites numbers in 2018 season. Incase of Cucumis plants, the highest seasonal mean of the three sprayers recorded were 86.00, 80.59 and 80.28 % on the thrips, green stink bug and mites numbers in 2018 season. The effect of the three sprayers on the tested predators as seasonal mean of reduction on the Cucumber plants caused the highest percentage of the decrease in the number of predators where it was 100.00, 79.23 and 70.37 % & 85.21, 66.11 and 63.02 % on aphid lion, lady bird beetle and true spider numbers in 2017 season in the two crops. While in the second season, the seasonal mean of the three sprayers on the Cucumber plants caused the highest percentage of the decrease in the number of predators where it were 89.67, 84.78 and 79.17 % on aphid lion, lady bird beetle and true spiders numbers in 2018 season. While in case of the effect of three tested sprayers on predators in Cucumis plants were 89.25, 57.75 and 47.79 % reduction on lady bird beetle, aphid lion and true spiders numbers, respectively