Variability in the Behavioural Responses of Three Generalist Herbivores to the Most Abundant Coumarin in Daphne Laureola Leaves
DOI: 10.1111/j.1570-7458.2009.00869.x Variability in the behavioural responses of three generalist herbivores to the most abundant coumarin in Daphne laureola leaves Conchita Alonso1,*, Isabel M. García1, Nelson Zapata2§ & Ricardo Pérez3 1Estacio´nBiolo´gica de Don˜ana, CSIC, Apdo. 1056, E-41080 Sevilla, Spain, 2Escuela Te´cnica Superior de Ingenieros Agro´nomos, Universidad Polite´cnica de Madrid, Avda. Complutense s ⁄ n, E-28040 Madrid, Spain, and 3Instituto de Investigaciones Quı´micas, Centro de Investigaciones Cientı´ficas Isla de La Cartuja, CSIC, Avda. Ame´rico Vespucio s ⁄ n, E-41092 Sevilla, Spain Accepted: 27 April 2009 Key words: chemical defences, diffuse coevolution, feeding behaviour, generalist host-range, plant– herbivore interactions, spurge-laurel, Lepidoptera, Noctuidae, Pseudenargia ulicis, Noctua janthe, Spodoptera littoralis Abstract We evaluated the responses of three generalist herbivores (Lepidoptera: Noctuidae) to the most abundant coumarin in young leaves of spurge-laurel, Daphne laureola L. (Thymelaeaceae), a peren- nial shrub consistently fed upon by several noctuid species. Pseudenargia ulicis Staud and Noctua jan- the Borkhausen are natural herbivores of the species in southeastern Spain, whereas Spodoptera littoralis Boisduval is a model species frequently used to address the antifeedant role of secondary compounds. Discrimination between control and coumarin-coated D. laureola leaves was investi- gated by short-term choice experiments. We found species-specific behavioural responses to the treatment: P. ulicis preferred the control leaves, whereas S. littoralis did not discriminate between leaf treatments, although it clearly avoided coumarin when incorporated into an artificial diet, and N. janthe preferred the coumarin-coated leaves. Furthermore, N. janthe larvae reduced consumption when the proportion of treated leaves ingested increased and consumption of S.
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