The hemolymph hormone(JH) titer was measured in over 500 flight-capable and flightless, adult female Gryllus firmus at 3-6 hours intervals during each of days 2-7 of adulthood. The flight-capable morph exhibited a large-amplitude daily cycle in the hemolymph JH titer, while the flightless morph exhibited a barely perceptible cycle. The JH titer cycle was observed on all days in the flight-capable morph, but the large amplitude cycle began on day 5. For both the large and small amplitude cycles, the JH titer peaked near the end of the photophase-begining of the scotophase. The hemolymph ecdysteroid titer did not exhibit a corresponding large amplitude daily cycle, although a low amplitude cycle(1-3 fold change) was seen in both morphs. The large magnitude rise in the JH titer in the flight-capable morph during the photophase was not due to decreased hemolymph volume or JH degradation. Daily cycles in the JH titer may be common, but may have gone unnoticed in other insect species due to restricted temporal sampling. Failure to identify these cycles can result in substantial errors in infering biological roles for JH. Because JH regulates flight behaviors, morph-specific daily cycles in the JH titer may be especially common in dispersal-polymorphic insects, in which flight is restricted to one morph during a limited peroid of the day or night.
Species 1: Orthoptera Gryllidae Gryllus firmus (Cricket)
Keywords: JH titer, wing polymorphism
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