Vol. 47 No. 2, 2008

Nymphal Growth, Life Cycle, and Feeding Habits of Potamanthus luteus (Linnaeus, 1767) (Insecta: Ephemeroptera) in the Bormida River, Northwestern Italy

Stefano Fenoglio1,*, Tiziano Bo1, José Manuel Tierno de Figueroa2, and Marco Cucco1

¹Dipartimento di Scienze dell,Ambiente e della Vita, Università del Piemonte Orientale, Via Bellini 25, 15100 Alessandria, Italy
²Departamento de Biologĺa Animal, Facultad de Ciencias, Universidad de Granada, 18071, Granada, Spain

Stefano Fenoglio, Tiziano Bo, José Manuel Tierno de Figueroa, and Marco Cucco (2008) Potamanthus luteus (Linnaeus, 1767), the only representative of the family Potamanthidae in Europe, exhibits explosive growth in terms of its numerical presence and mass increase in springtime.  The aim of this study was to analyze the pattern of the size increase, the life cycle, and the feeding habits of P. luteus nymphs in the Bormida River of northwestern Italy.  In particular, we investigated the growth patterns of 3 populations, located at stations at different elevations.  Thermal regimes of the 3 stations were assessed using a HoBo WaterPro Datalogger.  In 2006, immature stages of P. luteus were collected from the time they appeared in Mar. until their emergence as adults in June.  In total, 1407 nymphs of P. luteus were collected and measured.  Water temperatures differed between the 3 stations, and nymphs at the lowest, warmer station developed faster and emerged before nymphs at the upper stations.  This species shows a rapid univoltine seasonal life cycle.  The diets of the nymphs at the 3 stations were similar, being mainly based on fine detritus.  We suppose that higher temperatures strongly influenced bioenergetics and development and played a major role in fostering faster growth in the downstream population of this mayfly.

Key words: Mayfly, Potamanthidae, Nymphal biology, Apennines, Southern Europe.

*Correspondence: Tel: 39-01-31360201.  Fax: 39-01-31360391.  E-mail:fenoglio@unipmn.it