The susceptibility of eight varieties of tomato (Lycopersicum esculintum L.) namely Super Marmand, Prichard, Giza 80, Cherry, Money Maker, Castlerock, CAL-ACE and GS 12 to infestation with the whitefly (Bemisia tobaci Gennadius, Homoptera, Aleyrodidae) and artificial infestation with aphids (Aphis gossypii glover, Homoptera, Aphididae) was investigated.
In order to evaluate the effect of infestation with whitefly and tomato yellow leaf curl virus (TYLCV), the disease severity rate (D.S.R.) was used. Money Maker variety was the highest resistant, while Castle Rock showed high susceptibility for TYLCV. Also, this study amid to develop alternative management practices to prevent annual damage from infestation with aphids at different levels. The experiments were carried out during winter season of 2004 – 05 at Agricultural Research Station, EL- Kassasien, Ismailia Governorate , Egypt.
The results revealed that, Money Maker, Giza 80 and Castle Rock tomato varieties were the most resistant varieties as plants were attacked with few numbers of immature and adult stages of whitefly. Super Marmande and Prichard were the highest infestated varieties with whitefly stages. The, period of high infestation rates were January ,5th and January, 26th for adult stage and December, 1st and December,29th for Immature stages. This may be due to the use of pesticides which affected badly the natural balance of the pest (Hafez and Khalifa, 1975).
On the other hand, a positive correlation existed between aphid population levels and damage severity on plant.
The results indicated clearly that, early infestation with a little numbers of aphids lead to more damage and decreasing of the yield. Further, the infestation with one or two pairs of aphids necessitates the start of efficient aphid control program within the second week maximum.
Also , some vegetative and yield characters was measured for the most tested characters of the eight tomato varieties.