ABSTRACT
INFLUENCE OF WATER MITES ON A HEMIPTERAN COMMUNITY IN SPANISH WETLANDS: ENEMIES THAT LIMIT THE INVASION OF TRICHOCORIXA VERTICALIS?
The invasive species Trichocorixa verticalis (TVV) is originally from North America and has become the dominant Corixidae species in saline wetlands in the southern Iberian Peninsula. This study reports field studies and laboratory experiments which compare infection levels of parasitic water mites between TVV and native Hemipterans in the Doñana area of Spain. We studied the spatial and temporal variation of which mites parasitize which Heteropteran species, and the role of mites in the invasion of TVV. Corixids were much more affected than other Heteropterans, and TVV showed consistently higher infection levels by water mites (Eylais and Hydrachna) compared with the native corixidae Sigara lateralis and S. scripta. Experiments showed that infected Corixidae nymphs never reach the adult stage, while infected adults have a lower tolerance to salinity and fecundity. In conclusion, in contrast to "enemy release", our results suggest that the invasion success of TVV in natural wetlands of low salinity has been limited owing to a higher susceptibility to parasitic mites compared with native species.