Oriented responses of carrot fly larvae, Psila rosae , to plant odours, carbon dioxide and carrot root volatiles

The responses of carrot fly larvae, Psila rosae , to host plant volatiles were studied. Two criteria for an oriented response were used: one based on whether an individual reached within 1.5 cm of the odour source and one involving analysis of the track patterns of larvae within 3 cm of the odour source. All larval instars were attracted to both host and non‐host plant material, though to a lesser degree by the latter; they were also attracted to CO 2 , but not to N 2 . A steam volatile fraction of carrot roots, and methyl eugenol, a volatile component of this fraction, also attracted the larvae, differentially at different concentrations. The possible roles of both CO 2 and the host‐specific secondary plant volatiles in the host plant finding behaviour of soil inhabiting arthropods are discussed.