INTRODUCTION

Chrysopid taxocoenoses of the olive agroecosystem are well known and have been studied in nearly all Mediterranean countries (Canard & Laudého, 1977, 1980; Canard, 1979; Canard et al., 1979; Alrouechdi et al., 1980a, b; Neuenschwander & Michelakis, 1980; Neuenschwander et al., 1981; Neuenschwander, 1982; Campos & Ramos, 1983; Yayla, 1983; Alrouechdi, 1984; Liber & Niccoli, 1988). Pantaleoni & Curto (1990) suggested that they were influenced by environmental conditions such as the spatial pattern of trees, chemical treatments, and the surrounding vegetation, besides zoogeography.

The results of adult captures, where the species of the genus Dichochrysa often dominate, are, however, in contrast with the larval collection results, where Chrysoperla carnea (Stephens) s. lat. is by far the most abundant species, to the point that this species is practically considered the only chrysopid species developing on olive trees (Alrouechdi et al., 1980a; Neuenschwander & Michelakis, 1980). Some doubts on this conclusion were raised by Pantaleoni & Curto (1990) and Pantaleoni et al. (1993) who suggested that the efficiency of different sampling methods can be influenced by the behaviour of the different chrysopid genera and for these reasons the presence of some species can easily be underestimated.

The key pests in Sardinian olive agricultural systems are the olive fly, Bactrocera oleae (Rossi), the olive moth, Prays oleae (Bernard), and the black olive scale, Saissetia oleae (Olivier). Chrysopids can prey on the last two and are considered important predators of the olive moth (Ramos & Ramos, 1990).