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Free keywords:
Tiger beetles; Cicindelinae; cicindelids; gonad dormancy; floodplains; Amazon; Neotropics
Abstract:
The diurnal soil-dwelling cicindelid species Pentacomia egregia (Chaud.) inhabits Central Amazonian inundation forests. Adults pass the aquatic phase of several months duration on tree trunks. Experiments under simulated flood conditions with young beetles in climate-controlled chambers and in natural climatic conditions showed: (1) males have a shorter life span than females, (2) the mean temperature of the air influences gonad development in females but not in males, males will even copulate with immature females; (3) the presence of soil prevents gonad dormancy in females and continuous oviposition is observed. Results suggest, that the availability of soil is the primary or proximate (eco)factor which induces a rapid maturation of gonads and subsequent oviposition in females. The mean temperature of the air induces gonad dormancy and enhances longevity in females during inundation. It apparently has evolved as a cue for an adaptation to survive inundation as an ultimate factor. An increase in the mean ambient air temperature is correlated with seasonal changes in the water-level of the Solimões-Amazon River and the general climate in Central Amazonia
