Evidences that human disturbance simplify the ant fauna associated a Stachytarpheta glabra Cham. (Verbenaceae) compromising the benefits of ant-plant mutualism

Abstract

Interaction among species, like ants and plants through extrafloral nectaries (EFNs), are important components of ecological communities' evolution. However, the effect of human disturbance on such specific interactions and its ecological consequences is poorly understood. This study evaluated the outcomes of mutualism between ants and the EFN-bearing plant Stachytarpheta glabra under anthropogenic disturbance. We compared the arthropod fauna composition between two groups of twenty plant individuals, one in an area disturbed by human activities and one in a preserved area. We also check the plant investment in herbivory defense and the consequential leaf damage by herbivore. Our results indicate that such disturbances cause simplification of the associated fauna and lack of proper ant mutualist. This led to four times more herbivory on plants of disturbed areas, despite the equal amount of EFN and ant visitors and low abundance of herbivores. The high pressure of herbivory may difficult the re-establishment of S. glabra, an important pioneer species in ferruginous fields, therefore it may affect resilience of this fragile ecological community.Keywords: arthropods, environmental conservation, Myrmecophily, rupestrian fields, Stachytarpheta glabra. Evidências de que os impactos antrópicos simplificam a fauna de formigaassociada a Stachytarpheta glabra (Verbenaceae) comprometendo os benefícios do mutualismo formiga-planta ResumoAs interações entre espécies, como por exemplo formigas e plantas através de nectários extraflorais (NEFs), são importantes componentes na evolução das comunidades. Entretanto, pouco é conhecido sobre os efeitos dos impactos antrópicos em interações específicas e suas consequências ecológicas. Este estudo avaliou os resultados do mutualismo entre formigas e NEF em Stachytarpheta glabra em área impactada pela atividade humana. Nós comparamos a composição e estrutura da fauna de artrópodes, em quarenta plantas de dois grupos, um impactado por atividades humanas e o outro preservado. Nós também avaliamos o investimento da planta em defesas contra herbívoros e os danos foliares causados por herbívoros. Nossos resultados indicam que os distúrbios causam a simplificação da faunaBraz.

Extrafloral‐nectaries and interspecific aggressiveness regulate day/night turnover of ant species foraging for nectar on Bionia coriacea

“…Indeed, interaction with ineffective species can lead to lack of defense regardless of plant investment in nectar (Barbosa et al . ), and the plant must ensure continuous presence of the best protector ant species. We suggest that future studies investigate the consequences of day/night turnover of ant species for plant defense against herbivores.…”

Canopy cover negatively affects arboreal ant species richness in a tropical open habitat

“…This might be explained by a decrease in the number of species sensitive to warmer microclimate conditions in open vegetation habitats (Pino et al, 2000;Desrochers et al, 2011). Open-area species can replace shade-adapted species in disturbed forests (King et al, 1998;Madureira et al, 2012) and these species do not perform the same functions (Barbosa et al, 2015). Furthermore, there is a correlation between the thermal tolerance of ants and the environment in which they occur, as there are differences in temperatures of optimal foraging among species in the same community (Dunn et al, 2009).…”

Espaces verts comme une alternative de conservation de la biodiversité en villes : le cas des fourmis (Hyménoptère : Formicidae) dans le district d’Abidjan (Côte d’Ivoire)

“…En fait cet espace vert est peu influencé car, bien qu'on ait noté la présence d'émondes de gazon et de déchets anthropiques, la présence humaine était relativement faible. Des résultats analogues ont été obtenus par Barbosa et al (2015) et Graham et al (2004) qui ont montré que le degré et le type de perturbation d'un habitat contribuaient à réduire la diversité et la richesse spécifique des fourmis. En outre, la richesse spécifique élevée pourrait être également liée à la présence de lots vacants enherbés situés entre cet espace vert et la cité de la brigade anti-émeute.…”

“…Ce résultat suggèrerait qu'en plus de la taille des espaces verts, d'autres facteurs tels que les pressions anthropiques doivent être pris en compte pour expliquer la variation des paramètres de communauté de fourmis. Ces observations confortent celles d'autres chercheurs (Yamaguchi, 2004 ;Philpott et al, 2006;Fahrig et al, 2013;Barbosa et al, 2015) (Lindborg et al, 2012) la connectivité des habitats est un facteur important pour la préservation de la biodiversité dans le paysage urbain. Il soutient que la connectivité favorise le mouvement des espèces et permet le flux de gènes entre les espèces dans les taches d'habitat.…”