study of antixenosis and tolerance of nine commercial cultivars of tomato to the cotton-melon aphid, aphis gossypii glover (hem.: aphididae) under greenhouse condition

tomato, lycopersicum esculentum miller, is a grassy and annual plant from solanaceae family which is the most important farm plant after potato. the cotton-melon aphid, aphis gossypii glover (hem.: aphididae), is an important pests of tomato and vector of viral diseases in the farms and greenhouses. in the greenhouse its damage ranks second to the whiteflies (bemisia tabaci gennadius). in this research the antixenosis and tolerance of nine different tomato cultivars including: strian, caligen, super bita, super strian, super af1, has2274, gs-12-f1, sun-6200 f1 and calj was investigated in greenhouse. antixenosis experiments carried out throught counting the number of aphids attracted to each cultivar in four-leaf stage. in tolerance experiment, pots containing investigated cultivars in six-leaf stage within 21 days in a transparent plastic cage in which the top of it was blocked with a mash, was infected by 40 number of adult aphid. the results of antixenosis test indicate that, the highest number of aphids attracted to calj and the lowest number to super strian was observed. in addition, tolerance experiment showed that calj cultivar had the lowest tolerance, because of the highest reduction in both height and weight of this cultivar. therefore, it was concluded that the super strian, super bita and has2274 cultivars possess both antixenosis and tolerance mechanism to the melon aphid and they can be used as a resistant cultivars in ipm of the melon aphid.