Tamarix aphylla is a medicinal plant that grows well in arid areas and is widely regarded as one of the most significant plants for insect invasion. Tamarix aphylla trees cover a huge portion of the sand dunes in the Wadi Asel region in southern Sinai. Parapodia sinaica attacks Tamarix aphyllla and forms galls that hinder the growth and development of the plant. The aim of this study is to investigate the changes in phytohormone levels in Tamarix aphylla plants caused by insect infestation, especially by Parapodia sinaica insects that cause the formation of galls. In this study, indole-3-acetic acid (IAA), gibberellic acid (GA3) and Zeatin (Zn) were used in induced and non-induced plants during two distinct seasons, the dry and wet seasons between March and August 2021. The amount of each hormone was determined by high-performance liquid chromatography (HPLC). The level of (IAA) increased more in healthy plants in the wet season than in the dry season and decreased in infected plants. Zeatin (Zn) showed the same trend as in hormone (IAA). However, hormone (GA3) showed the same trend in both healthy and infected plant. The role and effects of entophytic fungus on galls caused by insects should be further investigated.
Keywords: Tamarix aphylla, Phytohormone, Gall-inducing insect, Parapodia sinaica.