Stenopelmus rufinasus Gyllenhal 1836

Fenoglio, Stefano, Bo, Tiziano & Bosi, G., 2006, Deep Interstitial Habitat as a Refuge for Agabus paludosus (Fabricius) (Coleoptera: Dytiscidae) During Summer Droughts, The Coleopterists Bulletin 60 (1), pp. 37-41 : 41

Stenopelmus rufinasus Gyllenhal 1836 ( Coleoptera : Erirhinidae ) Naturalized in Spain

Stenopelmus rufinasus Gyllenhal 1836 ( Coleoptera : Erirhinidae ) has been reported in Europe from Belgium, England, France, Germany, Holland and Italy (Caldara 2004). We recently detected the presence of this species in Spain, within the vicinity of the Parque Nacional de Doñana, Sanlúcar de Barrameda, Bonanza (coordinates 29SQA4078 and 29SQA4077, calculated by the Universal Transversal Mercator System). In May 2003 the weevil was found on mats of the invasive North American water fern Azolla filiculoides Lamarck , its main food source. The water fern is spreading into a great number of hot summer wetlands in Spain and Portugal where it is causing ecological problems to the native fauna and flora (Sanz-Elorza et al. 2004). Problems are caused by its floating habit and fast growth which enables it to out compete species for light, it can also lead to a reduction in water quality as a result of oxygen depletion. This is the second record of this weevil species in Spain, and is almost concurrent with its discovery by Fernández-Carrillo et al. (2005) in a continental area, 235 kms North of our locality. Since the species is host-specific (feeding exclusively on Azolla species ) it is considered to be a suitable biological control agent and has already proved effective in controlling populations of A. filiculoides in England, Reeder and Shaw (in prep.) and S Africa, Hill (1998 a, 1998 b); Hill and Cilliers (1999). Currently there is no effective, non-impact method of controlling Azolla spp . in Spain. While direct measures to reduce nutrient inputs into wetlands are initiated, the discovery of S. rufinasus suggests the possibility of managing populations of the weevil in order to reduce the ecological impact of A. filiculoides and offers, the only feasible, long-term solution for the affected wet lands.

It seems reasonable to assume that the current distribution of the species in the Iberian Peninsula could be broader than actually believed. Explorations for other populations and their relationships with local predators are urgently needed.