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Free keywords:
life cycle; seasonality; flood pulse; activity pattern; gonad state; Amazon
Abstract:
Terrestrial invertebrates in the Central Amazonian floodplains have to cope with an annual inundation period of several months. Their life cycles are affected by this flood pulse, and most species have adopted seasonal univoltine reproductive regimes as a common survival strategy. We followed the phenology of adult bombardier beetles, Pheropsophus rivieri, at a blackwater river beach near Manaus/Brazil during 1997-1999. Gonad maturity was examined in female beetles. Adult beetles showed a pronounced seasonal activity pattern with the reproductive period confined to the first three months of falling water levels. It is concluded that P. rivieri has a seasonal, univoltine. and presumably semelparous life cycle, driven by the flood pulse. The presence of fat bodies in immature females during rising water levels indicates a delayed gonad maturation or gonad dormancy. The species exhibits a migratory survival strategy, typical for most carabid species from Central Amazonian floodplains, although it remained unsolved where adults pass the period of rising water levels. A possible parasitic relation of larval P. rivieri with mole crickets is discussed
