Provisioning floral resources to attract aphidophagous hoverflies (Diptera: Syrphidae) useful for pest management in central Spain.

Noncrop plant communities present on the boundaries or within crop fields are essential for the maintenance of functional biodiversity, affecting beneficial insect numbers and ecological fitness. Habitat manipulation is an increasingly studied strategy aimed at enhancing natural enemies of agricultural pests by providing feeding and shelter resources. In this study, six plant species selected from preliminary work were tested for their potential attractiveness to four common aphidophagous hoverflies species. Potential attractiveness was evaluated through observation of hoverfly feeding visits to replicated flower plots distributed in a randomized design. The combination of the selected species covered a 2-mo full-bloom period. Sphaerophoria scripta L. and Sphaerophoria rueppellii (Wiedeman) were the dominant hoverflies present throughout the sampling period, whereas Eupeodes corollae (F.) and Episyrphus balteatus (DeGeer) visits were less abundant and appeared only in the early season. Potential attractiveness varied among plant species. Calendula arvensis L. and Coriandrum sativum L. were the most visited species. C. arvensis received a high number of visits throughout a long period, whereas the visits to Co. sativum were concentrated in a short blooming period. These results suggest that habitat management by using these plant species may increase the abundance of hoverflies and could improve the biological control of aphid pests typical of spring-summer crops in open Mediterranean environments.