Long-term trends in the composition of aphidophagous coccinellid communities in Central Europe

Coccinellids (Coleoptera: Coccinellidae) provide important ecosystem services as biocontrol agents in contributing to the regulation of key agricultural pests. It is generally accepted that biodiversity of native coccinellid communities has been declining during recent decades. Here, we present the results of a long-term study of coccinellid communities and report an attempt to determine whether recent changes in land use have affected their composition. Coccinellids were sampled in cereal crops, on wild herbaceous plants and deciduous trees during two periods (1976-1983 and 2002-2010). There are similar species-rich communities of coccinellids on trees and wild herbaceous plants (average numbers of species 3.18 and 3.06, respectively) and a poorer community on cereals (2.63). Only a few species, associated with particular types of vegetation, differed in their absolute abundance in the first and second period. There was no obvious cause of this variation in abundance. Diversity of coccinellid communities was higher in the second than in the first period (Shannon-Wiener index 1.32 and 1.14 respectively), although the number of individuals was lower (average catch per sampling session 10.0 and 18.6 individuals respectively). Over the 35years of this study, the compositions of the communities remained essentially similar with the numbers of particular species more closely correlated in the two periods on cereals (R-2=0.97) than on herbaceous plants (R-2=0.74) and trees (R-2=0.67).