Entomologica Romanica Vol. 19 / 2014


Entomologica romanica 19: 05-12, 2014/15 ISSN 1224-2594 / article no.: ER1920141501 Adaptation of a simple technique for rearing lotic mayfly (Insecta: Ephemeroptera) nymphs Éva Váncsa, Zoltán Csata & László Rákosy Summary: Rearing aquatic insects has puzzled scientists in different fields of biology and enlarged our knowledge about the tax­onomy, biology, ethology, ecology of the reared species. The laboratory maintenance of lotic aquatic insect larvae is extremely difficult and time consuming due to their habitat adaptations. Above all, it requires expensive equipment. A simple and inexpensive facility is introduced here from aquaculture and adapted for indoor rearing of lotic insect larvae. The efficiency of the “reversed­­funnel” method was tested on last instar mayfly nymphs belonging to several taxa. Young instars of Ecdyonurus sp. were also reared to reveal the suitability of the system for long-term indoor maintenance of especially sensible lotic mayflies. Owing to the results of the evaluation it is expected that the described method will provide a wider access to life-history experiments of mayflies and will be successfully applied to other lotic taxonomic units as well. Key words: “reversed-funnel” method, rearing chamber, lotic mayflies, emergence success, rearing success Introduction Rearing aquatic insects has often played a maj or role in a large number of studies from different disciplines in biology. In recent years the usage of reared material started to gain importance in molecular surveys (Ball 2001, Funk et al. 2006, 2010, Wilcock et al. 2005) and the employment of rearing facilities has become a prerequisite of ecotoxicity tests (Echols et al. 2010, Greve et al. 1998, Soeter et al. 2010, Yokoyama et al. 2009). The laboratory maintenance of aquatic insect larvae is continually practiced not just for taxonomic purposes, like description of novel species (Funk et al. 2006, González et al. 2000, Haybach 2005, 2006) and corroboration of larval identification (Bonada et al. 2004, Huryn & Wallace 1985, Urbanic 2006), but also for understanding the biology (Elliott 2009, Gupta et al. 1993, O’Donnell 2009), ethology (Gaino et al. 2002, Gallepp and Hasler 1975, Gallepp 1974, Spänhoff et al. 2003) of the reared species. Important ecological aspects of different stages of aquatic macroinvertebrates are also revealed by rearing studies (Kock et al. 2006, Lieske and Zwick 2007, Spänhoff 2005, Wiley and Kohler 1980), several of them highlighting the importance of environmental factors in life history events (Bohle 1972, Enders and Wagner 1996, Wagner 1986, 1990) and in the maintenance of diel behavioral patterns (Gallepp 1976). Moreover, the application of different rearing temperature regimes in the same survey (Aurich 1992, Giberson and Rosenberg 1992, Inoda 2003, Knispel et al. 2006, Wagner 1990) forecasted the birth of global warming-related rearing experiments (Feuchtmayr et al. 2007, McKee and Atkinson 2000). Both outdoor and indoor devices form the basis of rearing investigations. Simple cages (Jannot et al. 2007, Mochizuki et al. 2006, Tiunova 1997), plastic boxes with steel gauze sides (Wagner 1986), plastic tubes (Elliott 1978) or more complicated equipment consisting of rearing chambers and coolers (Sandberg and Stewart 2005) submerged into creeks or even enclosed recirculation stream chambers imbedded in the substrate of the watercourse (Pennuto and DeNoyelles 1993) make possible the in situ rearing. The ex situ outdoor experiments are realized mostly with the aid of large microcosm and mesocosm tanks, flow-through systems (Feuchtmayr et al. 2007, McKee et al. 2000, Sweeney 1976). The techniques used for the laboratory maintenance of aquatic insects are more diverse. They offer both lentic and lotic artificial habitats and their complexity depends mostly on the requirement of the species but also on the duration and purpose of the study.