Indirect effects of mutualism: ant-treehopper associations deter pollinators and reduce reproduction in a tropical shrub

Autor(es)

Ibarra-Isassi, Javier ^{[1, 2]} ; Oliveira, Paulo S. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Estadual Campinas, Dept Biol Anim, BR-13083862 Campinas, SP - Brazil

^[2] Concordia Univ, Dept Biol, Montreal, PQ H4B 1R6 - Canada

• Tipo de documento: Artigo Científico
• Fonte: Oecologia; v. 186, n. 3, p. 691-701, MAR 2018.
• Citações Web of Science: 3

Resumo

Animal-pollinated plants can be susceptible to changes in pollinator availability. Honeydew-producing treehoppers frequently occur on inflorescences, potentially enhancing ant-mediated negative effects on pollination services. However, the effect of ant-attended, honeydew-producing insects on plant reproduction remains uncertain. We recorded the abundance of treehoppers and ants on Byrsonima intermedia (Malpighiaceae), and monitored floral visitors in a Brazilian cerrado savanna. We manipulated the presence of ants and ant-treehopper associations on inflorescences to assess their effect on pollination and fruit formation. We used dried ants pinned to inflorescences to evaluate the effect of ant presence and ant identity on potential pollinators. Results show that the presence of treehoppers increases ant abundance on flowers and disrupts pollination by oil-collecting bees, decreasing the frequency and duration of floral visits and reducing fruit and seed set. Treehopper herbivory has no direct effect on fruit or seed production, which are independent of treehopper density. Pinned ants promote avoidance by floral visitors, reducing the number of visits. Ant identity mediates visitation decisions, with Ectatomma brunneum causing greater avoidance by floral visitors than Camponotus rufipes. Field videos show that pollinating bees are harassed by ants near flowers, prompting avoidance behavior by the bees. This is the first demonstration of indirect effects by honeydew-gathering ants, via disrupted pollination, on plant reproduction in tropical cerrado savanna. Our results highlight the importance of studying other interactions near flowers, in addition to just observing pollinators, for a proper understanding of plant reproduction. (AU)

• Processo FAPESP: 14/12486-8 - Interações entre formigas, flores e visitantes florais em vegetação de cerrado: estudo de caso com Byrsonima intermedia A. Juss. (Malpighiaceae)
• Beneficiário: Javier Eduardo Ibarra Isassi
• Modalidade de apoio: Bolsas no Brasil - Mestrado
• Processo FAPESP: 14/23141-1 - Ecologia de interações, ecologia comportamental e biologia molecular de formigas neotropicais
• Beneficiário: Paulo Sergio Moreira Carvalho de Oliveira
• Modalidade de apoio: Auxílio à Pesquisa - Programa BIOTA - Regular