Developmental changes in biogenic amine levels in the central nervous system and the haemolymph of the Eastern Death's Head Hawk Moth, Acherontia styx (Lepidoptera: Sphingidae)

In an effort to understand the role of biogenic amines in insect development, changes in the levels of octopamine (OA), dopamine (DA), epinephrine (E), norepinephrine (NE), and serotonin (5-HT) in the brain, the optic lobes and the haemolymph of different developmental stages of Acherontia styx were analyzed using HPLC with electrochemical detector. In the brain, OA was the most abundant monoamine. DA, OA, and E levels in larvae peaked around the wandering stage (W). A dramatic increase in DA, 5-HT, and E levels was observed in the brain of the adult as compared to the pupal stage. NE, however, was not detected in the brain of most stages of the insect, except in the brain of 20-day-old pupae and adults. A 3-fold increase in OA levels was observed in the optic lobes of the adult as compared to late pupal stage. No changes were observed for E, DA, and 5-HT. NE was not detected in the optic lobes. In the haemolymph of 5th instar larvae, OA was also the most abundant amine. Both DA and OA peaked prior to the onset of the W stage. In contrast, E and NE concentrations decreased with development of the 5th instar larvae. 5-HT was not detected in the haemolymph. Finally, different profiles for amine levels were observed for the two forms of the 5th instar larvae (green vs brown). These results are interpreted in the light of the role of biogenic amines and their relation to development in the nervous system of lepidopteran insects.