Resistance of some soybean varieties to bemisia tabaci (genn.)‎ (homoptera : aleyrodidae)‎ and thrips tabaci l. (thysanoptera : thirpidae)‎ in Assiut

الملخص EN

The present investigations were conducted at the Experimental Farm of the Agriculture Research Station, Arab-El-Awamer (Abnoub district), Assiut Governorate during 2013 and 2014 soybean growing seasons.

The obtained results showed that the populations of T.

tabaci and B.

tabaci started in a few numbers on all soybean varieties during the first week of July in 2013 and 2014 seasons.

The peak populations of these pests occurred during August and/or during September and ranged from 1 to 3 peaks for T.

tabaci and from 1 to 2 peaks for B.

tabaci according to each variety.

Results also indicated that there were highly significant differences in susceptibility between the soybean varieties (F = 7.72 and 18.84 > 0.01) and between seasons (F = 10.44 and 4.27 > 0.01) for T.

tabaci and B.

tabaci populations, respectively.

The combined effect of the weekly mean of maximum and minimum temperature, average relative humidity and predator populations was responsible for 81.80 % and 87.10 % of the changes in the populations of T.

tabaci and B.

tabaci during the two seasons of study.

Concerning the resistant status of the tested soybean varieties to the whitefly and the cotton thrips, the results showed different susceptibility degrees to these pests.

The cultivars H 117, G 22 G 111 and H 32, G 22, G 111 appeared as susceptible (S) to the cotton thrips and the whitefly infestations, respectively.

Meanwhile, the cultivars H 117, H 30, Clark and H 117, H 127, H 30 Clark appeared as low susceptible (LR) to the aforementioned pests infestations, respectively.