Midgut of Coleopteran Larvae, the Possible Target Organ for the Action of Neurohormones

Abstract

Detailed knowledge concerning the role of neurohormones in the regulation of metabolic processes in the larvae of insects is still lacking. In our previous studies, a functional relationship between the physiologic state of the neurosecretory cells of brain and midgut proteolytic activity in larvae of Tenebrio molitor and Morimus funereus was reported. Moreover, prolonged exposure of the larvae to certain temperatures resulted in reversible inactivation of the neurosecretory system (APPLEBAUM et al., 1964; IVANOVIC et al.; 1975a; IVANOVIC et al., 1975b; JANKOVIC-HLADNI and GROZDANOVIC, 1969). This work studies the role of neurohormones in regulation of midgut proteolytic and amylolytic activities in phytophagous larvae of two coleopteran species of very different phylogenetic age: T. molitor (Tenebrionidae) and M. funereus (Cerambycidae).