Hoverfly (Diptera: Syrphidae) diversity in Tapada da Ajuda, Lisbon – a preliminary study

Abstract

Hoverflies are holometabolic insects, whose adults are pollinators feeding on nectar and pollen. Frequently, they are confused with wasps, bees and bumblebees. In the larval stage, some of them prey other insects, specially aphids (Hemiptera), and others are saprophagous. For this reason, they are important biological control agents. In this study, we carried out the prospection and specific identification of hoverflies in four habitats in Tapada da Ajuda (olive grove, a field of Apiaceae, herbaceous vegetation near Lagoa Branca and plum orchard), between March and May 2017. Hoverfly adults were mostly captured with an entomologic net, but also with jar and plastic bags. A preliminary evaluation on the importance of ecologic infrastructure fava bean inter-row in the plum orchard was also performed. For this purpose, we observed fava plants and plum trees, collecting eggs, larvae and pupae of hoverflies that we reared in the laboratory until the emergence of the adult of hoverfly or parasitoid. A total of 12 species were identified, being the most frequent and abundant Episyrphus balteatus and Sphaerophoria scripta. Species richness was higher in the Apiaceae field although this habitat was sampled only during the last fortnight of the study. In the hoverfly immature collected in the plum orchard we detected hymenopteran parasitoids belonging to Diplazontinae and Pteromalidae.