Leaf traits, water stress, and insect herbivory: Is food selection a hierarchical process?

BISIGATO, A. J.; SAÍN, C.L.; CAMPANELLA, M.V.; CHELI,G.H.

ARTHROPOD-PLANT INTERACTIONS

SPRINGER

Lugar: Berlin; Año: 2015 vol. 9 p. 477 - 485

1872-8855

Plant water stress can affect selectivity by insect herbivores. Numerous studies have shown greater insect preference for water stressed plants, but others have reported the opposite response. We evaluated leaf consumption by adults of Nycteliacircumundata (a chewing insect) in leaves of Larrea divaricata and Prosopis alpataco. Three bioassays (two-way choice tests) were performed: two intra-specific comparisons between well-watered (+W) and water-stressed (-W) leaves of each species, and one inter-specific comparison between leaves of the two species. Leaf biomass was reduced by water stress in both species. Nitrogen concentration in leaves (N) was reduced by drought in P. alpataco. In contrast,total phenolics and specific leaf area (SLA) did not differ among treatments within species. Nyctelia circummundata did not show preference by any water supply regimes in intra-specific comparisons. In contrast, in inter-specific choice tests it showed a marked preference for P. alpataco, which is the species with the highest nitrogen concentration and lowest total phenolics concentration. In intra-specific comparisons, maximum leaf consumption was inversely related with SLA in both species. Furthermore, in P. alpataco N concentration was positively related to maximum leaf consumption and negatively related to leaf water content (LWC). In contrast, in inter-specific comparisons total phenolics was negatively related with maximum leaf consumption, while N concentration exhibited the opposite trend. These results suggest that food selection is a hierarchical process where chemical attributes (i.e. total phenolics and N) are taken into account for species selection, and physical attributes (i.e. SLA and LWC) for choosing individuals inside species.