The phytohormones cytokinin and auxin have been found in high concentrations in gall inducing insects at concentrations much higher than in the galled plant tissues. Auxin and cytokinin are plant growth hormones that induce cell growth and cell division which would contribute to the proliferation of the plant tissues that constitute the gall. The aim of the study is to determine if the location of the phytohormones auxin and cytokinin, within the insect are consistent with their production by the insect, or if they are concentrated in the gut which would be consistent with their being obtained by consumption of plant tissues. To further understand the contribution of insect or plant production of cytokinin and auxin to gall induction, immunological antibody staining techniques and dot blot procedures are used to localize the presence of three forms of gall inducing phytohormones, auxin (IAA) and cytokinin (isopentenyladenosine and trans-zeatin riboside) within gall inducing insects.
Results/Conclusions /Implications
Through the immunolocalization of cytokinin, there is support for the hypothesis that elevated levels of phytohormones in gall-inducing insects result from production by the insect. This is due to large amounts of trans-zeatin riboside localized to the salivary glands and absent in other parts of the body. This work would inform future directions of gall induction studies to determine the ultimate cause of tissue growth in galled plant species. E. solidaginis is a member of the same family Tephritidae, which have species that are agricultural economic pests. One specific member of note is the Olive Fruit fly, Bactrocera oleae, is a species of fly that is a significant pest of olive crops. Knowledge of the mechanism of tumor induction may lead to more effective means to control gall-inducing agricultural insect pests.