Luis Abdala-Roberts1, Johnattan Hernández-Cumplido2, Luis Chel-Guerrero3, David Betancur-Ancona3, Betty Benrey4, Xoaquín Moreira5. 1. Departamento de Ecología Tropical, Campus de Ciencias Biológicas y Agropecuarias, Universidad Autónoma de Yucatán. Km. 15.5 Carretera Mérida-Xmatkuil. 97000. Mérida, Yucatán, México. 2. Department of Entomology, Rutgers University, P.E. Marucci Center, Chatsworth, New Jersey 08019, USA. 3. Facultad de Ingeniería Química, Universidad Autónoma de Yucatán. Periférico Norte, Km. 33.5, Colonia Chuburná de Hidalgo Inn. 97203. Mérida, Yucatán, México. 4. Institute of Biology, Laboratory of Evolutionary Entomology, University of Neuchâtel, Rue Emile-Argand 11, 2000 Neuchâtel, Switzerland xmoreira1@gmail.com betty.benrey@unine.ch. 5. Misión Biológica de Galicia (MBG-CSIC), Apdo. 28 36080 Pontevedra, Galicia, Spain xmoreira1@gmail.com betty.benrey@unine.ch.
Abstract
PREMISE OF STUDY: Although there is increasing recognition of the effects of plant intraspecific diversity on consumers, the mechanisms by which such effects cascade-up to higher trophic levels remain elusive. METHODS: We evaluated the effects of plant (lima bean, Phaseolus lunatus) intraspecific diversity on a suite of insect herbivores (leaf-chewers, aphids, and seed-eating beetles) and their third trophic-level associates (parasitoids and aphid-tending ants). We established plots of three plants, classified as monocultures of one population source or polycultures with mixtures of three of the four population sources (N = 16 plots per level of diversity). Within each plot, plants were individually placed in pots and canopy contact was prevented, therefore eliminating diversity effects on consumers arising from changes in plant traits due to plant physical interactions. KEY RESULTS: Plant diversity reduced damage by leaf-chewers as well as aphid abundance, and the latter effect in turn reduced ant abundance. In contrast, plant diversity increased the abundance of seed-eating beetles, but did not influence their associated parasitoids. There were no effects of diversity on seed traits potentially associated with seed predation, suggesting that differences in early season herbivory between monocultures and polycultures (a likely mechanism of diversity effects on plants since plant interactions were prevented) did not drive concomitant changes in plant traits. CONCLUSIONS: This study emphasizes that effects of plant intraspecific diversity on consumers are contingent upon differences in associate responses within and among higher trophic levels and suggests possible mechanisms by which such effects propagate up this food web.
PREMISE OF STUDY: Although there is increasing recognition of the effects of plant intraspecific diversity on consumers, the mechanisms by which such effects cascade-up to higher trophic levels remain elusive. METHODS: We evaluated the effects of plant (lima bean, Phaseolus lunatus) intraspecific diversity on a suite of insect herbivores (leaf-chewers, aphids, and seed-eating beetles) and their third trophic-level associates (parasitoids and aphid-tending ants). We established plots of three plants, classified as monocultures of one population source or polycultures with mixtures of three of the four population sources (N = 16 plots per level of diversity). Within each plot, plants were individually placed in pots and canopy contact was prevented, therefore eliminating diversity effects on consumers arising from changes in plant traits due to plant physical interactions. KEY RESULTS: Plant diversity reduced damage by leaf-chewers as well as aphid abundance, and the latter effect in turn reduced ant abundance. In contrast, plant diversity increased the abundance of seed-eating beetles, but did not influence their associated parasitoids. There were no effects of diversity on seed traits potentially associated with seed predation, suggesting that differences in early season herbivory between monocultures and polycultures (a likely mechanism of diversity effects on plants since plant interactions were prevented) did not drive concomitant changes in plant traits. CONCLUSIONS: This study emphasizes that effects of plant intraspecific diversity on consumers are contingent upon differences in associate responses within and among higher trophic levels and suggests possible mechanisms by which such effects propagate up this food web.
Authors: Christopher T Cole; Clay J Morrow; Hilary L Barker; Kennedy F Rubert-Nason; Jennifer F L Riehl; Tobias G Köllner; Nathalie D Lackus; Richard L Lindroth Journal: Ann Bot Date: 2021-03-24 Impact factor: 4.357