Root feeding behaviour of Tipula paludosa (Meig.) (Diptera: Tipulidae) on Lolium perenne (L.) and Trifolium repens (L.)

The larvae of the cranefly, Tipula paludosa (Meig.), graze on plant root systems and are a prevalent pest of upland grassland. Using a slant board system, their effect on two pasture species, Trifolium repens L. and Lolium perenne L. were studied. The larvae fed voraciously on the main root axes of T. repens, causing a 15% reduction in primary axis root length. In contrast, there was no overall effect of grazing on root length of L. perenne. However, the proportion of the root system of L. perenne present as laterals was reduced. The plant N content of T. repens was reduced by grazing, possibly due to leakage of N-containing compounds or selectivity of N-rich tissue by the grazing invertebrate. Larvae were larger when fed on T. repens, and their faeces had a higher concentration of bacteria than when fed on L. perenne.