Eva Maria Zimmermann

Eva Maria Zimmermann


Frugivorous Noctuoidea in the Danube flood plain east of Vienna – guild structure and reproductive biology

The aim of this thesis was to investigate local biodiversity and reproductive biology of fruit feeding central European noctuoid moths: firstly, if there are differences in species richness, diversity and composition between flooded and non-flooded areas of a riparian forest area in Eastern Austria, and secondly to determine possible fitness benefits that might accrue to these moths from feeding on rotting fruits. For tropical butterflies, it has been shown that feeding on rotting fruits, rather than nectar, is important to achieve high adult life expectancy and may have large positive effects on their reproductive output. Many European cold season noctuid moths also avidly feed on such resources.
Between September 2005 and November 2005, fruit-feeding noctuoid moths were caught using sugar baits in flooded and non-flooded areas of the National Park Donau-Auen. This yielded a sample of 444 individuals from 34 species in 22 genera. Species richness showed no significant differences between flooded and non-flooded areas. Species composition showed significant phenological differences, but not between areas. Species diversity (measured as Shannon's exponential index) was higher in non-flooded habitats than in areas prone to annual inundation. Field-caught individuals of 5 species were fed sucrose solution, sucrose solution enriched with vitamins, or banana slices plus sucrose solution, respectively, under identical greenhouse conditions. These moths represented three life cycle types (autumn species, adult hibernators, and early spring species). Benefits were expected to be especially pronounced in moths which overwinter as adults, in relation to their unusually long and thus nutrient-demanding imaginal lifespan (6–9 months). Indeed, adult food type significantly affected length of the oviposition period, mature oocytes remaining within the abdomen, potential fecundity and egg size. Some of these effects were contingent on species identity or life cycle type.