The role of non-crop habitats on hoverfly (Diptera: Syrphidae) foraging on arable land.

Abstract

Observations were made of syrphid behaviour in two floristically different types of field-margins.  In particular, the use made of arable weeds by adult hoverflies was studied to facilitate the development of selective weed control strategies for field-margins, to maximise the biocontrol potential of arthropod natural enemies.

The two field-margin types consisted of an established hedgerow and a boundary strip, left fallow and subsequently colonised by annual, arable weeds.

Ten commonly-occurring species of hoverfly were recorded at both sites.   The relative contribution of individual syrphid species to the site totals varied with field-margin type.

Flowers were not visited according to their abundance; particular species of fly showed a "preference" for certain weeds.  A "Forage Ratio" was used to quantify this preference, which varied with the species of hoverfly studied and according to the habitat composition.  Implications for the management of non-cropped areas on farmland are discussed.