Stress-induced Changes in the Biogenic Amine Levels and Larval Growth of Tribolium castaneum Herbst

Abstract

Such stress factors as mechanical (vibration), thermal (unfavorable temperature), optical (light), and starvation reduced the larval growth of the red flour beetle (Triholium castaneum Herbst). Various biogenic amines, including octopamine (OA), dopamine (DA), serotonin (5-HT), epinephrine (E), norepinephrine (NE), their precursors, and metabolites, in whole-body T. castaneum were measured by high-performance liquid chromatography coupled with electrochemical detection (ECD). Tyrosine occurred in the highest concentration, followed by OA, tryptophan, and 3,4-dihydroxymandelic acid. The amount of OA was much higher than that of tyramine (a precursor of OA in the biosynthetic pathway) and of synephrine (N-methyl OA). DA, 5-HT, E, NE, and their related substances occurred in extremely low quantities compared with OA. Insects were stressed by vibrating at 1, 10, 100, or 1000Hz, optically under a 24-h light (15W, 50Hz) photoperiod, thermally by changing the incubation temperature from an initial value of 30°C, or by starvation, which resulted in dramatic changes of levels of biogenic amines, including OA.