Identification and Studying the Population Density of Insect Pests Infected Cucumber Cucumis sativus L. in the Green Houses

Abstract

Abstract                                                                                                                                                          The study was conducted in the green house, in the college of Agriculture/ Department of Plant Protection in Abu-Gharib from 2. 2. 2015 to 25. 4.2015 to determine the pests of cucumber and    the population density of them. Results showed that the white fly (Bemisia tabaci (Genn.), Thrips onion (Thrips tabaci ), cotton leaf worm ( Spodoptera littoralis (Bosid) ) and tomato leaf miner (Liriomyza sp.) were presented only during the study period. The highest population density of white fly occurred in the first of April, it recorded on the lower part of the plant, in comparison with the middle and top parts of the plant, it was 21, 6 and 5  nymph/leaf  respectively, in the same period. While, the highest population density reached 0.1 larve /leaf for the cotton leaf worm in the three parts of the plant during last February to mid March and from last March to mid April.While, in the mid study, it was found in top part of the plant. It wasn't record any number in the middle and lower parts of the plant. Concerning Thrips onion and Tomato leaf miner infestation reported on the for cucumber from last March to the end of the study. The population density of Thrips onion recorded highest average on the middle part of the plant in comparison to the top and lower parts of the plant, which reported to be 12, 9 and 7 nl/ leaf respectively. While the highest population density recorded on the lower part of the plant were 2.5 larve/ leaf for leaf miner, in comparison to the middle and top parts of the plant which were 1.8 and 0.9 la/leaf respectively. The peak of infection of cotton leaf worm was 5.9 pore/leaf at the end of March and the lowest was 0.2 pore/leaf at the end of April, while the higher average of pores was 2.55 at lower part of the plant and the lowest was1.5 at the top part of the plant. The highest severity of the infection was 3.44 miners/ leaf for Tomato leaf miner at the first of April and the lowest was 0.82 m/l at the end of March. The highest of the average infection was 2.83 in the lower part of the plant. While it reached to 1.69 in the top part of the plant. This results revealed that the insects under this study were preferred fresh leaves of the plant and suitable environmental condition which encourage infection.