The impact of the North American waterbug Trichocorixa verticalis (Fieber) on aquatic macroinvertebrate communities in southern Europe

The North American waterbug Trichocorixa verticalis (Heteroptera: Corixidae) has recently invaded brackish water systems on three continents. Despite its potential to be a keystone species in hypersaline waters in its home range, its effect on the communities it invades is yet unstudied. By doing a field survey in 29 ponds in Doñana, southern Europe some years after T. verticalis was first recorded there, we aimed to establish its prevalence and impact on the local invertebrate community, especially the local corixid community with which it is likely to compete. T. verticalis showed the highest prevalence among all seven Corixidae species found. It occasionally reached high local abundance, especially at high salinity. T. verticalis also appeared to be better than native Corixidae at coping with human disturbance. We could not identify significant effects of T. verticalis on the local corixid community nor on the invertebrate community at large. Further experimental research will be needed to confirm these results. Special attention should be paid to hypersaline systems where T. verticalis may act as a top predator.