Hoverfly diversity (Diptera: Syrphidae) of Pyrenean oak woodlands in Central-Western Spain: a preliminary study with conservation outcomes

Abstract

Hoverflies are frequently used as biodiversity indicators and are targets of ecological studies across Europe. How hoverfly diversity responds to ecological variables is essential for species and habitat conservation. The present study is a first attempt to assess the hoverfly diversity of deciduous woodlands of Pyrenean oak (Quercus pyrenaica) in La Vera (Central-Western Spain), a habitat in need of conservation and a region that is poorly known in terms of hoverflies. Hoverflies were sampled with hand net in a mature-woodland site, a young-woodland site, and two close-by grassland sites. A higher number of species and individuals was recorded in woodland sites than in grassland sites, with only two species exclusive to the grasslands and thus, suggesting that woodland sites might be acting as a hoverfly reservoir and source. The proportion of species with phytophagous and saprophagous larvae in woodland sites was higher than outside the woodlands, probably due to a higher availability of resources in woodland sites for phytophagous and saprophagous species. The mature woodland was found to have a higher number of species and individuals than the young woodland, possibly due to the presence of grassy clearings and rotting materials in the trees of the mature woodland. The highest number of species was found in the predatory guild (Syrphinae), and smaller-bodied species within this guild were found to be more frequent in grassland than in woodland sites; possible explanations for this result are discussed. Further investigation is required to confirm and expand the results and conclusions found in this initial study on the hoverfly community of the poorly studied Q. pyrenaica woodlands of Central-Western Spain.