Inter‐ and intra‐ species differences in plants as hosts to Tyria jacobaeae

Abstract

AbstractThe effect of three food plants, Senecio jacobaea L., Senecio vulgaris L. and Tussilago farfara L., and rust infection of two of them on the performance and host choice of Tyria jacobaeae L. was assessed. The nitrogen content of healthy and infected food plants was measured.Larvae reared on S. vulgaris had a lower relative consumption index and higher efficiency of conversion of ingested food than those reared on the other two species. These differences were correlated with the higher nitrogen content of S. vulgaris compared to T. farfara and S. jacobaea. Larvae reared on T. farfara were significantly smaller at pupation than those reared on the other species. In both larval and adult choice tests between healthy plants of the three species, S. jacobaea was always the preferred host plant. Adults completely avoided T. farfara in oviposition choice tests.Infection of S. vulgaris with Coleosporium tussilaginis (Pers) Lev. had no effect on larval performance. Infection of S. vulgaris with Puccinia lagenophorae Cooke. caused differences in larval performance. Infection of T. farfara with C. tussilaginis had a detrimental effect on larval performance: larvae were smaller, fed for longer and had lower growth rates than those reared on healthy T. farfara. Healthy T. farfara had a higher leaf nitrogen content than the infected T. farfara. In choice tests against healthy leaves, larvae avoided leaves of both S. vulgaris and T. farfara infected with C. tussilaginis. Larvae and adults showed no preference between S. vulgaris leaves infected with P. lagenophorae or healthy leaves.In the field, factors such as plant size may be important in dictating adult and larval preference for a particular host plant species. Rust infection of some species influenced larval performance and host choice, demonstrating the importance of studying multitrophic aspects of plant – insect interactions.