An investigation of the host range of the carrot fly

Abstract

SUMMARYThe historical records of the earliest reports of umbelliferous and other hosts of carrot fly (Psila rosae) are presented and their validity discussed. In addition, the results are reported of tests made between 1972 and 1980 on 27 species of Umbelliferae and three sub‐species of Daucus carota to determine whether they would support the carrot fly. Techniques were developed for identifying plant species as hosts by determining the number of adult flies that emerged from root and soil samples obtained from plants exposed to carrot fly in the field. Experiments in 1979 and 1980 indicating the importance of co‐ordinating the life cycles of plant and insect. The results showed that certain annual species of Umbelliferae were unsuitable as hosts in the autumn when they has flowered and senesced. Valid records could only be obtained for these species by exposing the plants to first generation carrot fly attack. Of the 27 species tested, Anthriscus sylvestris, Ferula communis, and Smyrnium olusatrum failed to support carrot fly and the following 13 species were new host records: Aethusa cynapium, Anthriscus caucalis, Apium inundatum, Apium nodiflorum, Bupleurum tenuissimum, Chaerophyllum temulentum, Cicuta virosa, Daucus capillifolius, Daucus glochidiatus, Heracleum mantegazzianum, Ligusticum scoticum, Oenanthe crocata and Sison amomum. From two species, Chaerophyllum temulentum and Torilis japonica, more than two carrot flies/root were recovered. These species are numerous and widespread in carrot‐growing districts. The significance of these and other wild host plants in relation to the ecology and control of carrot fly is discussed.