Insectary Plant Species Preferences of Predators and Parasitoid Families in a Mediterranean Horticultural Agroecosystem

Abstract

The use of insectary plants to provide alternative food and shelter resources for enhancing natural enemy activity has been established as a common practice in IPM. Candidate flowering plant species have been screened and evaluated for their contribution to enhance life parameters of beneficial insects. However, less information has been reported on the preference of these natural enemies for different insectary plant species in the field. The relative attractiveness of six insectary plant species to the key natural enemy groups on horticultural crops in the Mediterranean region was assessed by observing the relative frequencies of appearance on six plant species: Achillea millefolium L. and Calendula officinalis L. (Asterales: Asteraceae), Daucus carota L. (Apiales: Apiaceae), Diplotaxis tenuifolia (L.) DC. (Brassicales: Brassicaceae), Fagopyrum esculentum Moench (Caryophyllales: Polygonaceae), and Lobularia maritima (L.) Desv. (Brassicales: Brassicaceae). The presence of predators and parasitoids was evaluated by visual counts. Among predators, Syrphidae adults were evaluated by visual observation of inflorescence visits and/or hovering. The other predators recorded on the insectary plants were collected and divided into six groups: Aeolothripidae, Araneae, Chrysopidae, Coccinellidae, Dicyphini tribe, and Orius spp. Parasitoids were also collected and grouped into families. The Syrphidae interacted the most with D. tenuifolia, F. esculentum, and L. maritima, the last one being the plant with higher proportion of visits after hovering on the inflorescence. Parasitoids were recorded the most on A. millefolium and L. maritima. Finally, significant differences were found in the preference of each group of predators for the six insectary plants. The different natural enemy groups preferences for the insectary plants are discussed in biological control context and of the key influencing factors that should be considered when assessing the relative attractiveness of natural enemies to the insectary plants.