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

BISIGATO ALEJANDRO; SAÍN CLAUDIA; CAMPANELLA M VICTORIA; CHELI GERMÁN H.

Arthropod-Plant Interactions

University of Helsinki

Lugar: Helsinki ; Año: 2015 p. 477 - 485

Plant waterstress can affect selectivity by insect herbivores. Numerous studies have showngreater insect preference for water-stressed plants, but others have reportedthe opposite response. We evaluated leaf consumption by adults of Nyctelia circumundata (a chewing insect)in leaves of Larrea divaricata and Prosopis alpataco. Three bioassays(two-way choice tests) were performed: two intra-specific comparisons betweenwellwatered (+W) and water-stressed (-W) leaves of each species and oneinter-specific comparison between leaves of the two species. Leaf biomass wasreduced 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 between treatments within species. Nyctelia circumundata did not show preference by any water supplyregimes in intra-specific comparisons. In contrast, in inter-specific choicetests, it showed a marked preference for P.alpataco, which is the species with the highest nitrogen concentration andlowest total phenolics concentration. In intra-specific comparisons, maximumleaf consumption was inversely related to SLAin both species. Furthermore, in P.alpataco, N concentration waspositively related to maximum leaf consumption and negatively related to leafwater content (LWC). In contrast, in inter-specific comparisons, totalphenolics was negatively related to maximum leaf consumption, while Nconcentration exhibited the opposite trend. These results suggest that foodselection is a hierarchical process where chemical attributes (i.e., total phenolicsand N) are taken into account for species selection, and physical attributes(i.e., SLA and LWC) for choosing individuals insidespecies.