INSECT NEUROPEPTIDES REGULATING SUBSTRATE MOBILIZATION

Insect flight muscles perform their work completely aerobically, and w orking flight muscles are known to be the most metabolically active ti ssue in nature with respect to oxygen uptake. Various substrates can b e oxidised and utilised as fuels for flight. Insects such as Diptera a nd Hymenoptera power their flight muscles by the breakdown of carbohyd rates, whereas lipids are the predominant fuel for the contracting fli ght muscles of Lepidoptera and Orthoptera during long-distance flight. The amino acid proline can also be used as a substrate for flight, es pecially in tsetse flies and beetles (Colorado potato beetle, blister beetles, certain dung beetles). Neuropeptides from the corpus cardiacu m are well-known to be responsible for carbohydrate and lipid mobilisa tion from the fat body. In this short overview, we show that peptides belonging to the large adipokinetic hormone/red pigment-concentrating hormone family are also thought to be the chemical messengers for init iating proline homeostasis. The peptides isolated and sequenced so far from glands of beetles from the genera Pachnoda, Scarabaeus and Oniti s all have a tyrosine residue (at position 2 or 4) and seem to be rela ted to each other.