INTRODUCTION

Olive cultivation is of great importance in the Mediterranean Basin, representing 97% of world production. Spain, with 27% of world production, is the foremost olive-growing country in the world in terms of surface area under cultivation, and 60% of the national production is concentrated in Andalusia (Porras Piedra et al., 1995; Barranco et al., 1997).

Factors that have a negative impact on this crop include pests, diseases, and weeds, for which losses in yield can reach 30% (De Andrés Cantero, 1991). Among the 18 recognised insect pests, the three most serious are: Bactrocera oleae (Gmelin), the olive fruit fly; Prays oleae (Bernard), the olive moth; and Saissetia oleae (Olivier), the olive scale (Bellido, 1975; Campos, 1976; Briales, 1984; Civantos, 1995). Currently, protection against these pests relies on concepts of integrated control based on knowledge of the environment and of the population dynamics within the agricultural systems and, in this sense, both chemical as well as biological methods are used. The aim is to reduce the insect populations to levels at which the damage caused does not exceed certain economic thresholds (Civantos & Sanchez, 1994; Civantos, 1995).

The utilisation of entomophagous insects plays a key role within the widest concept of integrated olivepest control. Most of the work performed to date on natural enemies in southern Spain has focused on parasitoids (Jimenez et al., 1969; Campos & Ramos, 1981; Briales & Campos, 1985; Montiel Bueno & Santaella, 1995) rather than on the predators (Morris, 1997). However, numerous studies have been conducted on chrysopids, given that lacewing larvae are major oophagous predators of the olive moth (Montiel Bueno, 1981; Ramos et al., 1983a, b).