The population density of the white fly, Bemisia tabaci (Genn.), the cotton aphid, Aphis gossypii Glov., jassids, Empoasca spp. and the spider mite, Tetranychus urticae Koch. were evaluated on three soybean varieties (Giza 35, Giza 82 and Clark) at Sakha Agricultural Research Station Farm, Kafr El-Sheikh during two successive seasons; 2008 and 2009 as well as its relation to hair numbers on leaf and chlorophyll content.
The obtained results indicated that B. tabaci started to appear with higher numbers than the other pests during the two study seasons and its population was the highest ,while T. urticae. was the least. B. tabaci recorded two peaks of abundance in every season ( on 28th June and 23rd August, respectively). Both Empoasca spp. and T. urticae recorded its maximum on 26th July in the two seasons. One peak of abundance for A. gossypii occurred in the first season (26th July) and two peaks in the second season (12th July and 23rd August).
The statistical analysis indicated insignificant differences in chlorophyll content of leaf between the three varieties in spite of the differences in the population of the considered pests, while the hair density on leaf significantly affected the pest population. Giza 35 which possessed the highest number of hairs on leaf, harbored the highest population of B. tabaci and T. urticae and the lowest population of A. gossypii. The highest number of A. gossypii occurred on Clark variety which had the low number of hairs on leaf. Giza 82 was the least infested with A. gossypii and T. urticae and had a moderate number of hairs on leaf. The three tested varieties did not appear a significant differences to infestation with Empoasca spp. Thus, the varieties that had a low number of hairs on leaves should be used as a safe and easy tool in the integrated pest management program to reduce the infestation with the harmful pests of soybean.