Plasticity of medial neurosecretory neurons in response to nutritive stress in the gypsy moth Lymantria dispar (Lepidoptera : Lymantriidae)

Abstract

The activity and number of the protocerebral neurosecretory neurons of the dorso-medial group (A1, A2 and A1') were investigated in the 5(th) larval instar of Lymantria dispar Linnaeus 1758 originating from two populations (oak and locust-tree forest) and fed with two host-plants (oak as a suitable and locust-tree as an unsuitable host-plant). The results of a combined monitoring of activity related cytological parameters, and a number of protocerebral dorsomedial neurosecretory neurons showed that differently adapted populations responded to nutritive stress in different manner. The activity and the number of the A1 neurosecretory neurons was high in the protocerebra of the caterpillars fed locust-tree leaves regardless of the population origin. The unsuitable host-plant led to the decrease in the secretory activity and number of A2 neurosecretory neurons in the oak population, while their number was high in locust-tree caterpillars regardless of the host-plant. High activity and increased number of the A1' neurosecretory neurons were found in the caterpillars from the locust tree forest.