INTRODUCTION

During the 15 years since the publication of the last comprehensive book on lacewings (Canard et al., 1984), some excellent reviews have been published on the ecology of lacewings (New, 1986, 1989; Bay et al., 1993). Certain chapters of the present book cover ecological issues (such as food selection and utilisation, life-cycle characteristics, diapause, assessment of the impact of lacewings, natural enemies of lacewings, biodiversity conservation, enhancing chrysopids in field crops) and for this reason this chapter mainly focuses on issues relating to field ecology, in particular on lacewing patterns that are characteristic of different temporal and spatial scale levels, organisation of lacewing guilds, and chemical relationships between lacewings and the environment (chemical ecology).

The study of various spatial and temporal scale levels has great importance (Wiens et al., 1986) in ecological issues. Knowledge of the dynamic processes of differing scale levels may be used in conservation of natural enemies and enhancement of their impact in agricultural or forest habitats.

TEMPORAL PATTERNS OF LACEWINGS

Long-term fluctuation patterns and population dynamics

Few studies have been carried out on year-to-year population changes of lacewings. In order to recognise real population dynamics, changes in the abundance of species and environmental factors should be observed over numerous generations in the same localities.

Ressl (1971) and Gepp (1973) published long-term data on individual numbers of chrysopids without any evaluation. Over ten (1961–1970) and nine (1964–1972) years' study in Austria, Ressl and Gepp respectively reported the yearly numbers of lacewings.