Systemic changes in tomato induced by foliar treated hormone and cultivar interactions reduce the fitness of an invasive specialist herbivore, tomato leafminer.
Plant hormones are the compounds that are increased followed by the attack of herbivores to enhance plant defense ability. The idea of external application of hormones on crop plants to induce resistance to herbivores has been studied by examining the behavioral and physiological responses of tomato leafminer, Tuta absoluta (Lepidoptera: Gelechiidae) on three tomato cultivars including Dehghan, Falat-111 and Mobil in response to jasmonic acid and salicylic acid hormone treatments by measuring the oviposition preference of the females, survivorship and development time of each immature stage and the concentration of soluble carbohydrates and phenols in the leaves. Oviposition preference of females and embryo development time on the susceptible cultivar, Falat-111, were significantly reduced and increased respectively in jasmonic acid treatment units. Larval development rate showed the highest response to hormonal treatments in the semi-resistant cultivar, Dehghan. Survivorship and development rates of the pupae were also significantly reduced under the influence of jasmonic acid treatments on all three cultivars. Despite significant differences in leaf soluble carbohydrates and phenols concentrations between control and sprayed tomato cultivars as well as a significant positive correlation between changes in carbohydrates and phenols concentrations in the experimental units, no significant correlation was observed between the aforementioned plant contents and insect biological variables. The results showed that these hormones in combination with appropriate plant varieties can be used to induce behavioral and physiological changes in the pest.