Differences among ant species in plant protection are related to production of extrafloral nectar and degree of leaf herbivory

Abstract

Many studies assume that all ant species collecting extrafloral nectar defend plants against herbivores, although ant-plant interactions are facultative, generalized and have variable outcomes. With over 280 h of observations in an area of Rupestrian Grasslands (Ouro Preto, Brazil), we described the network of interactions between 2313 ants of 23 species and 200 plants of 10 species. Ants from all species were further submitted to an identical task of finding and removing a standardized herbivore surrogate (termites) to quantify the relative protection effectiveness of different ant species. We then correlated ant protection to the volume and concentration of sugar in the nectar as conditional factors and the herbivory damage as interaction outcome. We found that 11 of the 23 species of ants attacked and removed 933 of 2000 termites. All plant species interacted with effective ant protectors, although the identity of the best protector varied among plants. The degree of ant protection was positively associated with sugar concentration of nectar, which further explained the variation in leaf damage among plant species. Our study provides evidence that ant protection varies among ant species and is enhanced by the plant investment in nectar reward, resulting in less herbivory for the partner plant. We also showed that the most protecting ant species are those that are most connected and thus spread the benefit throughout the network.

Effects of chronic anthropogenic disturbance and rainfall on the specialization of ant–plant mutualistic networks in the Caatinga, a Brazilian dry forest

“…According to this paradigm, specialist species are good at a few services, while generalists are mediocre at many services. However, a recent study on the plant protection services provided by ants showed that the most protective ant species might be the most generalist as well (Fagundes et al., ). Unfortunately, this study examined protection against non‐natural plant enemies, and we still need to learn more about the effectiveness of mutualisms protecting against natural enemies before making predictions about how protection services change depending on environmental conditions.…”

“…In this study, we focused on the facultative mutualistic networks established between plants bearing extrafloral nectaries (EFN) and the ants that attend them. EFN‐bearing plants produce carbohydrate‐rich resources, which attract ants that often then protect the plants against herbivores (Bentley, ; Fagundes, Dáttilo, Rico‐Gray, Jordano, & Del‐Claro, ). Although such networks occur in many different ecosystems (Rico‐Gray & Oliveira, ), the protection provided by ants to EFN‐bearing plants appears to be particularly effective in arid environments (Leal & Peixoto, ).…”

“…In this study, we focused on the facultative mutualistic networks established between plants bearing extrafloral nectaries (EFN) and the ants that attend them. EFN-bearing plants produce carbohydrate-rich resources, which attract ants that often then protect the plants against herbivores (Bentley, 1977;Fagundes, Dáttilo, anthropogenic disturbances, creating a geographic mosaic of selective forces that may shape the co-evolution of interactions between ants and EFN-bearing plants.…”

“…anthropogenic disturbance, anti-herbivore defence, climate change, extrafloral nectaries, mutualistic network, plant-animal interactions, seasonally dry tropical forest, specialization Rico-Gray, Jordano, & Del-Claro, 2017). Although such networks occur in many different ecosystems (Rico-Gray & Oliveira, 2007), the protection provided by ants to EFN-bearing plants appears to be particularly effective in arid environments (Leal & Peixoto, 2016).…”

Disturbance‐modulated symbioses in termitophily

“…Specifically for the ants here studied, at least two unidentified congeneric species of Camponotus rufipes have been already described by Higashi and Ito () to be highly dependent and eager defenders of their host nest, built by the termite Armitermes laurensis . Camponotus rufipes itself, a typical nectar‐feeding ant (Schilman & Roces, ), is very aggressive in defending resources, being highly efficient in locating and removing threats from their patrolled plants (Fagundes et al., ). Likewise, the seed harvester (Carroll & Risch, ) fire ant Solenopsis geminata also found in the termitaria here inspected, is notorious by its aggressive behavior (Wauters, Dekoninck, Herrera, & Fournier, ), preying upon vertebrates such as turtles (Wetterer & Lombard, ), birds hatchlings and chicks (Wetterer, ), and rats (Pimentel, ), being also able to reduce the diversity of arthropods in areas to which it has been introduced (Wetterer, ).…”