Quantifying biodiversity in ecosystems with green lacewing assemblages

Green lacewings are pertinent bio-indicators of an ecosystem’s health. An example for detecting temporal changes in crop field biodiversity over a short period by sampling chrysopids is given. Light-trapping collections over ten years near Bucharest (Romania) implied changes in the species assemblages. The main species present were members of the Chrysoperla carnea-complex. They increased from 38 to 72% of the total Chrysopidae in samples. The faunistic richness (Margalef’s index) only decreased by about 9% of its initial value. Shannon’s diversity and Hurlbert’s equitability indices showed a high level of biodiversity for an agri-environment. Nevertheless, they decreased significantly by about 45% over time, attesting to a loss in biodiversity. Statistical analysis by linear and logistic regressions shows that the progressive dominance of the common green lacewings is realistic, and constitutes indication of change in crop field biodiversity