Encyrtidae (Hymenoptera) Parasitoids of Soft Scale Insects on Olive Trees in Mediterranean Regions

Abstract

Surveys of Encyrtidae (Hymenoptera) associated with soft scale insects infesting olive trees (Olea europaea L.) were conducted across Mediterranean orchards to document parasitoid diversity, host associations, and potential for biological control. Field sampling of scale-infested branches revealed a complex of soft scale species, predominantly Parlatoria oleae and Saissetia oleae, supporting a diverse assemblage of encyrtid parasitoids. Emergence of parasitoids from collected scale populations under laboratory rearing conditions enabled taxonomic identification based on morphological characters and confirmed by mitochondrial COI gene sequencing. Several Encyrtidae species, including Metaphycus spp. and Coccophagus spp., were recorded as dominant parasitoids contributing to natural regulation of scale insect populations. Parasitism rates varied across locations and seasons, with higher activity observed during spring and early summer corresponding to peak host availability and favorable climatic conditions. Phylogenetic analysis indicated close relationships among Mediterranean populations, suggesting regional adaptation and possible gene flow between orchard systems. The presence of multiple parasitoid species within single host colonies indicates strong potential for complementary biological control interactions. However, variability in parasitism intensity suggests that environmental factors, orchard management practices, and host density significantly influence biological control efficiency. The study highlights the ecological importance of conserving natural enemy diversity in olive agroecosystems and emphasizes the role of habitat management in enhancing parasitoid effectiveness.