Ants have a negative rather than a positive effect on extrafloral nectaried Crotalaria pallida performance

Autor(es)

Pereira, Marcela Fernandes ^[1] ; Trigo, Jose Roberto ^[1]

Afiliação do(s) autor(es)

^[1] Univ Estadual Campinas, UNICAMP, Inst Biol, Lab Ecol Quim, Dept Biol Anim, BR-13083970 Campinas, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: ACTA OECOLOGICA-INTERNATIONAL JOURNAL OF ECOLOGY; v. 51, p. 49-53, AUG 2013.
• Citações Web of Science: 16

Resumo

Crotalaria pallida (Fabaceae) is a pantropical plant with extrafloral nectaries (EFNs) near the reproductive structures. EFN-visiting ants attack and remove arctiid moth Utetheisa ornatrix larvae, the main pre-dispersal seed predator, but the impact of ants on C pallida fitness is unknown. To assess this impact, we controlled ant presence on plants and evaluated the reproductive output of C pallida with and without ants. Predatory wasps also visit EFNs, prey upon U. matrix larvae, and may be driven out by ants during EFN feeding. Does this agonistic interaction affect the multitrophic interaction outcome? We found it difficult to evaluate the effect of both visitors because cages excluding wasps affect plant growth and do not allow U. ornatrix oviposition. Therefore, we verified whether ant presence inhibited wasp EFN visitation and predicted that (1) if ants confer a benefit for C pallida, any negative effect of ants on wasps would be negligible for the plant because ants would be the best guardians, and (2) if ants are poor guardians, they would negatively affect wasps and negatively impact the fitness of C pallida. Surprisingly, we found that the number of seeds/pods significantly increased, ca. 4.7 times, after ant removal. Additionally, we unexpectedly verified that controls showed a higher percentage of herbivore bored pods than ant-excluded plants. We found that wasps spent less time visiting EFNs patrolled by ants (ca. 299 s less). These results support our second prediction and suggest that the outcome of multitrophic interactions may vary with natural enemy actors. (C) 2013 Elsevier Masson SAS. All rights reserved. (AU)

• Processo FAPESP: 05/01154-5 - Custos e beneficios do terceiro nivel trofico na protecao de plantas contra insetos fitofagos: crotalaria pallida e crotalaria spectabilis (fabaceae): um estudo de caso.
• Beneficiário: Marcela Fernandes Pereira
• Modalidade de apoio: Bolsas no Brasil - Mestrado