UBC Theses and Dissertations
Host plant resistance to whitefly Trialeurodes vaporariorum in the genus Lycopersicon Veilleux, Richard Ernest
The greenhouse whitefly (Trialeurodes vaporariorum) is one of the most destructive pests of greenhouse tomato (Lycopersicon esculentum) crops. The success of biological or insecticidal control of whiteflies has never been complete. Attention has therefore been directed recently to the possibility of developing tomato cultivars resistant to whiteflies. Whiteflies were caged on leaflets of ten tomato cultivars, two of the woolly mutant lines and four other species of Lycopersicon to observe the effect of host plants within this genus on fecundity and longevity of the insects. The results showed wide variation among hosts. Significant negative correlations were revealed between the mean density of glandular hairs on the upper foliar surface of different cultivars and means for the fecundity of whiteflies caged on these cultivars. A high level of resistance to whitefly, not related to density of glandular hairs, was observed in plants that were either Van Wert's woolly mutant or L. peruvianum var. humifusum. Resistance of the former seemed to be related to a high density of branched non-glandular trichornes whereas that of the latter was not morphologically apparent. There were indications of both antibiosis and nonpreference operating in the humifusum. Further experimentation revealed a high nymphal mortality for whiteflies developing on plants of this line, reduced fecundity of adults which had developed on the humifusum, and a preponderance of male progeny from adult insects which had lived exclusively on these plants. It was concluded that the resistance of L, peruvianum var. humifusum to whitefly is sufficient to justify its use in a breeding program to develop greenhouse tomato cultivars resistant to this pest.
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