Stimulation of the endocrine system by flight in grasshopper, Melanoplus sanguinipes, was examined. It is known that long flight accelerates reproduction in this species. Since juvenile hormone is related to reproduction in most species, we first checked juvenile hormone titer after long flight using chiral specific radioimmunoassay.
Using chiral specific radioimmunoassay, hemolymph samples of 5ml could be analyzed in individual animals. There was no difference in juvenile hormone titer between virgin and mated females. So only virgin females were used in the following experiments. Hoppers were flown to exhaustion on day 4 after eclosion and bled from day5 through day15 with 3-day intervals to give them enough time to recover. When titer determinations were compared with unflown controls, there were increases in JH titer on day5 and day 8. It is the first report to show that JH titer is altered after long flight.
In order to know if JH titer increases are caused by adipokinetic hormone that is released during long flight, 20pmole of adipokinetic hormone was injected into 4 day old animals for 6 hours with 1 hour intervals to simulate long flight. There was no difference in JH titer on day 5 and day 8. Therefore it seems that JH titer increases are not caused by released AKH. It is not known whether the increased JH titer and enhanced reproduction are casually related or merely a chance of correlation and further experiment is on going now.
Species 1: Orthoptera Acrididae Melanoplus sanguinipes (northern migratory grasshopper)
Keywords: migration, adipokinetic hormone
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