Role of plant age in the resistance of Lycopersicon hirsutum f. glabratum to the tomato leafminer Tuta absoluta (Lepidoptera : Gelechiidae)

The objective of this work was to study the role of plant age in the resist ance of tomato, Lycopersicon hirsutum, to the tomato leafminer Tuta absolut a (Meyrick). Determination of the levels of tridecan-2-one and undecan-2-on e in L hirsutum were made at three different ages (2-4 months after germina tion), as well as the leaf area, and the density and types of trichomes pre sent on L. hirsutum and L. esculentum. This information gathered was correl ated with the following biological characteristics of ir: absoluta: rates o f oviposition and egg eclosion; length of egg, larval and pupal stages; mor tality in the larval and pupal stages; pupal weight and proportion of femal es. I: absoluta showed higher oviposition and egg eclosion, as well as lowe r mortalities and shorter larval and pupal periods in L. esculentum than in L. hirsutum. The proportion of females obtained was also higher on L. escu lentum. The rate of egg eclosion and proportion of females as well as the l ength of the larval stage and the mortality of larvae appeared to be affect ed by plant age. A higher proportion of females, mortality of larvae and le ngth of the larval period were obtained with older plants of L. hirsutum, w hile the rate of egg eclosion, was higher for L. hirsutum plants that were 3 months old. For L. esculentum, plant ageing increased larval mortality. I t seems that the glandular trichome density in L. hirsutum increased with p lant age leading to an increase in the levels of tridecan-2-one, which slow s larval development, (C) 2001 Elsevier Science B.V. All rights reserved.