olerant varieties to insect species represent one of the simplest and important methods of insect pest control to minimize the insecticide hazards. Therefore, susceptibility of five soybean varieties to infestation with some piercing-sucking insects: aphids, Aphis spp.; whitefly, Bemisia tabaci (Genn.) and leafhoppers, Empoasca spp. were evaluated at Sakha Agric. Res. Station Farm, Kafr El-Sheikh Governorate during 2016 and 2017 seasons. The obtained results showed significant differences in susceptibility between the tested soybean varieties to the mentioned insects for every season and from season to another. In general, the population density of whitefly and aphids were higher in the first season than the second one, while the reverse was found for leafhoppers.Based on the grand mean number of the two study seasons, variety Crawford was significantly the most infested variety to infestation with leafhoppers and aphids, while the least infested variety for aphids was Giza35 and for leafhoppers was Hybrid30. As for the whitefly, Giza35 significantly was the most infested variety, while Crawford was the least infested one. In respect to the resistance status of the tested varieties to the insects, Crawford and Hybrid30 showed susceptiblity to aphid infestation, while the other varieties exhibited low resistance. Giza111 and Giza35 appeared as susceptible for whitefly, Giza21 and Hybrid30 showed low resistance, while Crawford was moderately resistant. Concerning leafhoppers, Giza111 and Crawford were susceptible. Giza21 showed low resistance, while Hybrid30 was moderately resistant.
n Egypt, aphids, Aphis spp.; leafhoppers, Empoasca spp. and whitefly, Bemisia tabaci (Genn.) are the most important piercing-sucking insect pests infesting soybean plants and a good understanding of their population dynamics is essential to develop an integrated pest management strategy. Therefore, the population densities of these insects and its relation to the common associated predators and the prevailing weather factors were investigated in soybean fields at Kafr El-Sheikh Governorate for 2016 and 2017 seasons. Weekly counts of the considered insects per 15 leaves indicated that whitefly was the most abundant species followed by leafhoppers, while aphids were the least one. Whitefly and leafhoppers appeared on soybean plants all over the growing season. The maximum density of whitefly took place from mid-June to late July in the first season and from the second half of July to the first half of August in the second season. The high number of leafhoppers occurred in the period from mid-July to mid-August for the first season and during August in the second season. Aphid population appeared only in two periods with very low numbers for every season. In the first season, the first period occurred in the second half of June, while the second period took place in the first half of September. In the second season, the population appeared from late June to mid-July and from late August to mid-September. Also, three predaceous insect species: Chrysoperla carnea (Steph.); Coccinella undecimpunctata L. and Orius spp. were observed on soybean plants. Ch. carnea was the most abundant predator, while C. undecimpunctata was the least one. The total of the predaceous insects attained the highest numbers during July in the first season and during July and August in the second one. The weather factors (temperature, relative humidity and wind speed) had insignificant effect on the cotton whitefly population in the two study seasons. As for leafhoppers, wind speed only had significant effect on the population activity in the second season. Temperature and wind speed in the first season and wind speed in the second season had highly significant effect on aphids activity in the first season. The effect of the predators on the insects was insignificant during the two seasons except effect of the predaceous insects on the leafhoppers which it was significant. The combined effect of both predators and the prevailing weather factors was more pronounced only on aphids in the first season and on leafhoppers in the second season. However, the gained results may provide valuable information for comprehensive integrated insect management of soybean.
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