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

BISIGATO, ALEJANDRO J.; SAIN, CLAUDIA L.; CAMPANELLA, M. VICTORIA; CHELI, GERMÁN H.

ARTHROPOD-PLANT INTERACTIONS

SPRINGER

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

1872-8855

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