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The well-studied interactions between ants and plants range from antagonistic relationships to mutualisms, but ant pollination studies are still overlooked. Here, we studied ant interactions with Microstachys serrulata shrubs in a tropical savanna, in Uberlândia, Brazil, highlighting the central role of ants in plant pollination. Additionally, we described the phenology and the main aspects of its floral biology. We evaluated the importance of ants for pollination, comparing the number of fruits produced between the treatments: control (all pollinator access), ant exclusion, flying insect exclusion, and exclusion of all visitors. We also evaluated floral visitors, pollen viability, and conducted experiments to test for apomixis. Furthermore, we described its phenology using observations throughout 1 year. We found an unspecialized guild of insects visiting the flowers, with ants being the most common visitors. Visitation by ants only was as effective as controls for producing fruit. Although other insects can act as pollinators, the high abundance of ants suggests they are the most effective pollinators. Minor fruit production occurred by apomixis, but the low number of fruits produced and the pollen–ovule ratio reinforce the need for a biotic pollinator. Our study shows that ants can act as pollinators in simplified systems and could thus be more important for pollination than previously expected. The Brazilian savanna has high ant diversity and many plants with low floral specialization, which may make it a favorable environment for ant pollination. We suggest that pollination by ants in dry or arid Neotropical environments is underestimated, but likely a critical interaction for many plant species. [ABSTRACT FROM AUTHOR]

The conversion of natural areas into agricultural systems and silviculture is the greatest threat to biodiversity in tropical ecosystems such as the Brazilian savanna (Cerrado). This landscape transformation could lead to the loss of native species, including ants that cannot tolerate the new environment dominated by exotic plant species, such as Eucalyptus spp. The present study aims to investigate ant diversity and their functional groups to verify which vegetation and landscape variables explain their changes in a neglected formation of Cerrado (Campos Murundus) surrounded by Eucalyptus forests planted. We sampled ants in 29 sites, which presented a gradient of richness, average plant heights, and distances from Eucalyptus plantations and permanent protected areas (PPAs). We found 83 ant species from six functional guilds (arboreal, Camponotini, epigeic omnivorous, higher Attini, lower Attini and specialist predators). Plant richness best explained the diversity of ants. Higher distance from Eucalyptus plantations also positively explained the frequency of functional groups, whereas higher distance from the PPAs negatively explained the frequency of Camponotini species. Our study showed that vegetation (plant richness) and landscape variables help to understand ant diversity in a Eucalyptus‐dominated landscape. This reaffirms the importance of preserving the vegetation and their associate fauna in Campos Murundus by increasing the extent of conservation of this threatened biome. [ABSTRACT FROM AUTHOR]

Plants bearing extrafloral nectaries ( EFNs) vary the secretion of nectar between day and night, which creates turnover in the composition of interacting ant species. Daily variation in the composition of ant species foraging on vegetation is commonly observed, but its mechanisms are poorly understood. We evaluated the daily variation in nectar availability and interspecific aggressiveness between ants as possible regulatory mechanisms of the turnover in ant-plant interactions. We hypothesized that (i) plants would interact with more ant species during periods of higher secretion of nectar and that (ii) aggressive ant species would compete for nectar, creating a daily turnover of species collecting nectar. We tested this hypothesis by measuring the production of nectar during the day and night and by experimentally removing EFNs of Bionia coriacea (= Camptosema coriaceum) (Nees & Mart.) Benth. (Fabaceae: Faboideae) plants in a Brazilian savanna (Cerrado). We then compared the abundance and composition of ant species between those treatments and during the day. Our results indicate that more ant workers forage on plants during the day, when nectar was sugary, while more ant species forage at night, when aggressiveness between ant species was lower. We also detected a day/night turnover in ant species composition. Ant species foraging for nectar during the day were not the same at night, and this turnover did not occur on plants without EFNs. Both dominant ant species, diurnal Camponotus crassus (Hymenoptera: Formicidae) and nocturnal Camponotus rufipes (Hymenoptera: Formicidae), were the most aggressive species, attacking other ants in their specific periods of forage while also being very aggressive toward each other. However, this aggressiveness did not occur in the absence of nectar, which allowed non-aggressive nocturnal ant species to forage only during the daytime, disrupting the turnover. We conclude that extrafloral-nectar presence and interspecific aggressiveness between ants, along with other environmental factors, are important mechanisms creating turnovers in ants foraging on plants. [ABSTRACT FROM AUTHOR]