Gall-inducing Psylloidea (Insecta: Hemiptera)–plant interactions

Abstract

The Psylloidea, >4000 named species known today, are plant-feeding, sap-sucking insects sleeved under the Sternorrhyncha. Most species of Psylloidea are confined to the tropics. They occur as gall-inducing, free-living, and lerp-forming taxa. Lifecycles and generations of gall-inducing Psylloidea vary in temperate and tropical worlds. The Triozidae, Aphalaridae, and Calophyidae include several taxa that induce galls of diverse morphologies, from simple pits and leaf-margin rolls to complex pouches and of two-tier structures. The feeding mechanism and nutritional physiology of the gall-inducing taxa of the Psylloidea differ from those of the free-living and lerp-forming species. A majority of the gall-inducing Psylloidea are associated with the dicotyledons and a small number with the monocotyledons. The gall-inducing Psylloidea are specific to certain plants. Their host specificity is regulated by specific lipids and sterols. The gall-inducing Psylloidea show conservative behavior in terms of geographical distribution. Although the life histories of several gall-inducing Psylloidea are known today, aspects explaining their association with host plants are little known. Details of nutritional physiology of gall-inducing Psylloidea are less known presently compared with that of the free-living species. A better understanding of the association and level of relationship between gall-inducing Psylloidea and their host plants is necessary.