Collecting of phytophagous dipteran larvae in oilseed rape roots

Abstract

The official plant protection services of various German federal states have, in recent years, reported an increasing infestation of oilseed rape with Diptera larvae mining in the roots. The aim of this study was to determine whether solely the Cabbage Root Fly (Delia radicum), or a combination of several species cause damage to rape roots. Larvae of Diptera were collected from feeding tunnels in oilseed rape roots, reared until the imago stage and determined to species level. We found 218 Cabbage Root Flies (Delia radicum) and 13 Cabbage Leaf Miners (Phytomyza rufipes). Up to now, the larvae of P. rufipes have only been known to feed by mining rape leaves and stems; therefore this is the first record for this species in oilseed rape roots. As all the P. rufipes larvae were found together with larvae of D. radicum in the tunnels, a coexistence of both species can be assumed.