Temporal variation in positive and negative interactions between marsh herbivores mediated by changes in plant traits

CANEPUCCIA, AD; ALEMANY, D; ESPINOSA VIDAL, E; ALVAREZ, MF; IRIBARNE, OO

MARINE ECOLOGY PROGRESS SERIES

INTER-RESEARCH

Año: 2020 vol. 634 p. 89 - 97

0171-8630

Studies onbidirectional benefactor−beneficiary interactions between organisms havegenerally neglected the importance of this feedback in trophic levels otherthan plants. The burrowing crab Neohelice granulata aids the development of larvae of the stem-boring moth Haim bachia sp. nov. within the stems of Spartina alterniflora. In our research, we evaluated whether the stem-boring moth subsequentlyinfluences crab feeding on these marsh plants. Surveys and experiments in atidal marsh of the SW Atlantic coast (36° 22? S) showed that at the beginning ofthe stem-boring moth attack there was no difference in crab herbivory betweenplants with or without larvae of the stem-boring moth. However, after 3.5 mo,crabs foraged more on plants without larvae than on those with larvae. Planttissue analyses showed a decrease in leaf tissue carbon concentrations inplants with larvae. This change in the nutritional quality of leaves, caused byconstruction of the stem-boring moth galleries, could explain the segregationin plant use between both herbivores. Unlike an allelochemical response, thenon-specificity of the induced nutritional change could impair a wide varietyof herbivores regardless of their feeding modes or taxonomic proximity. Theseeffects could propagate bottom-up through the food-web, leading to more diffuseinterspecific effects. Thus, here we show how the benefactor−beneficiary feedbackbetween herbivores can be important for the maintenance of species coexistenceand the functioning of communities