Interpretation of Susceptibility Phenomenon of Four Tomato Cultivars to Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae).

Abstract

The selected four tomato cultivars {(Alissa F1, Super strain B, G.S 12 F1and Logain (E603 F1)} differed in their susceptibilities to the tomato borer, Tuta absoluta in the two studied successive years (2013 and 2014). Seasonal abundance of this pest was higher in early summer and summer plantations of year 2013 than that recorded in year 2014. The highest seasonal mean number was recorded on Alissa cultivar for both studied years followed by Super strain cultivar then G.S. cultivar. While the lowest mean number was achieved with Logain cultivar. The essential oil analysis by GC/MS of four tomato cultivars leaves revealed the presence of 33 peaks. A total of 33 components of the essential oil were identified. Aliphatic hydrocarbons terpenes compounds were found to be the most abundant volatiles in the four tomato cultivars except G.S. cultivar. The analyses revealed that the major identified aliphatic hydrocarbon components in the leaves oil of Logain and Alissa tomato cvs. (The lowest and the highest infestation with T. absoluta) were Octacosane, Hexacosane, Triacontane, Heptacosane, Nonacosane, Tetratriacontane, Hexatriacontane and Tetracosane. Susceptibility interpretation of Logain and Alissa tomato cvs. to T. absoluta may be attributed to the presence of high contents of the toxic and repellent hydrocarbons octacosane and hexacosane in Logain tomato cv. and high content of the attractant hydrocarbon tetracosane in Alissa cv. From these results it can be recommend to use the tolerable Logain tomato cultivar in breeding programs and also, preparing a commercial product/formulation from hydrocarbons octacosane and hexacosane to be used as repellent and tetracosane as a trap to T. absoluta.