Nazanin Doryanizadeh - Department of Entomology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran.
Saeid Moharramipour - Department of Entomology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran.
Vahid Hosseininaveh - Department of Plant Protection, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran.
Mohammad Mehrabadi - Department of Entomology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran.

The melon aphid, Aphis gossypii (Glover), is one of the major pests of cucurbits and an efficient vector of plant viruses such as Cucumber Mosaic Virus. Host-plant resistance is one of the management strategies that can be used to control this pest. In this study, choice test was conducted to identify antixenotic resistance against melon aphid in eight Cucumis genotypes, namely Hormozgan, Bushehr, Guilan, Girtap, Negeen, Sepehr, Pouya and Armenian cucumber. Choice tests were conducted at ۲۵ ± ۱ ºC, ۶۰ ± ۵% RH and a photoperiod of ۱۶:۸ (L: D) h. After introduction of apterous adult aphids to test arena, the number of aphids on each entry was counted at ۲, ۴, ۶ and ۲۴ hours of release. Total phenolic content, NPK essential elements, leaf thickness and leaf trichome density were also measured to discover any association between these factors and aphid host choice. The most antixenosis effect was observed on 'Bushehr'. Increase in antixenosis correlated with increase in leaf trichomes. Antixenosis can be important mode of resistance by reducing host selection and delaying aphid colonization. The identification of antixenotic resistance in several genotypes provides additional options for management of this pest. Moreover, the factors associated with this mode of resistance can be considered in plant breeding programs.

antixenosis, Aphis gossypii, Cucumis, Total phenolic content, Trichome