FOOD VALUE OF INTRODUCED EUCALYPT LEAVES FOR A MEDITERRANEAN STREAM DETRITIVORE - TIPULA LATERALIS

1. Food preference, consumption and growth of Tipula lateralis feeding on leaves of one exotic (Eucalyptus globulus) and three native trees of central Portugal (Alnus glutinosa, Castanea sativa and Quercus faginea) were investigated. 2. Larvae preferred and consumed more alder than the other three species. Larvae fed oak and eucalyptus did not grow, while those fed alder had a faster mean specific growth than those fed chestnut. Alder also provided a higher and earlier peak growth rare, which occurred at 35 days vs. 91 days for chestnut. 3. High values of survivorship to 126 days were observed in larvae fed alder and chestnut. All larvae fed oak died within 63 days; those fed eucalyptus died within 91 days. 4. Leaf utilization by Tipula lateralis seems to be negatively correlated with cuticle thickness and polyphenolic content and positively correlated with microbial colonization and nutrient content of the leaves. We hypothesize that the replacement of the original deciduous forest by eucalyptus plantations may induce deleterious changes in the associated invertebrate communities and stream ecosystem processes.