Ant–herbivore interactions in an extrafloral nectaried plant: are ants good plant guards against curculionid beetles?

Abstract

Extrafloral nectary drinking ants are known as effective plant guards, but some herbivores may circumvent ant attacks by foraging on different plant parts or presenting adaptations to avoid ant predation. Here we experimentally investigated the effect of Camponotus blandus on the florivory of the extrafloral nectaried shrub Banisteriopsis malifolia; and a possible spatial segregation between ants and herbivores (leaves and flowers). Flower buds are attacked by Anthonomus weevils. Results revealed no significant influence of C. blandus on the reduction of florivory. Adult Anthonomus are hard-bodied and were immune to ant bites; larvae are endophytic, so protected from ants. Ants and adult beetles were concentrated in different plant parts (leaves and flowers, respectively) so restraining the probability of encounters. Our results indicate that the system C. blandus–Anthonomus–B. malifolia is not stable, as ants receive extrafloral nectar, but are unable to protect the plant against weevils.

Keywords:

• Anthonomus
• Banisteriopsis
• Camponotus blandus
• Cerrado
• extrafloral nectary

Acknowledgements

The authors would like to thank Xavier Arnan, Karsten Mody and Nico Blüthgen for comments and suggestions on earlier versions of the manuscript; the staff of the Clube de Caça e Pesca Itororó de Uberlândia, where the study was carried out; the Laboratory of Climatology of the Federal University of Uberlândia, who graciously provided the climate data used in the study; and three anonymous reviewers for their comments which increased the quality of the manuscript. We are also grateful to CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior), CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico), FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo) and DAAD (Deutscher Akademischer Austauscht Dienst) for financial support.