Plant species with larger extrafloral nectaries produce better quality nectar when needed and interact with the best ant partners

Few studies have explored the phenotypic plasticity of nectar production on plant attractiveness to ants. Here, we investigate the role of extrafloral nectary (EFN) size on the productivity of extrafloral nectar in three sympatric legume species. We hypothesized that plant species with larger EFNs (i) have higher induced nectar secretion after herbivory events, and (ii) are more likely to interact with more protective (i.e. dominant) ant partners. We target 90 plants of three Chamaecrista species in the field. We estimated EFN size and conducted field experiments to evaluate any differences in nectar traits before and after leaf damage to investigate the phenotypic plasticity of nectar production across species. We conducted multiple censuses of ant species feeding on EFNs over time. Plant species increased nectar descriptors after leaf damage, but in different ways. Supporting our hypothesis, C. duckeana, with the largest EFN size, increased all nectar descriptors, with most intense post-herbivory-induced response, taking its place as the most attractive to ants, including dominant species. EFN size variation was an excellent indicator of nectar productivity across species. The higher control over reward production in plants with larger sized EFNs reflects an induction mechanism under damage that reduces costs and increases the potential benefits of indirect biotic defences.

Ants (Hymenoptera: Formicidae) from an Amazonian fragmented landscape, Juara, Mato Grosso, Brazil, with new records of ant species

The state of Mato Grosso is the 3rd largest Brazilian state, is covered with three major Brazilian biomes, including the Pantanal, Cerrado, and Amazonia. To date, 449 ant species are recorded in literature for the state. In the present work, we documented the ants sampled along a fragmented landscape, in the municipality of Juara, in the Cerrado-Amazon transition zone in the state of Mato Grosso, Brazil. The ant species were captured with Pitfall traps installed in 20 trails with 10 traps in each (totaling 200). Our results show 151 species, belonging to 43 genera and eight subfamilies, of which 28 species were recorded for the first time in the state and five species recorded for the first time in Brazil. Most genera collected were Pheidole Westwood, 1839 (45 species) followed by Crematogaster Lund, 1831 (11 species). By highlighting species recorded for the first time in state of Mato Grosso and Brazil, we hope to encourage new discoveries and increase the general knowledge of the ant fauna of different biomes in the region.

Strumigenys fairchildi Brown, 1961 (Formicidae, Myrmicinae): first record of this rarely collected ant from Brazil

Strumigenys fairchildi Brown, 1961 is recorded for the first time in Brazil. This ant species was previously known only from a few specimens collected in Costa Rica, Panama and Ecuador. The worker S. fairchildi was collected at the Parque Estadual do Cristalino, a continuous area of Amazon tropical rain forest protected for biodiversity conservation in the municipality of Novo Mundo, Mato Grosso state. In addition, we present a distribution map and high-resolution images of the worker.

Differential Recruitment of Camponotus femoratus (Fabricius) Ants in Response to Ant Garden Herbivory

Although several studies have shown that ants can recognize chemical cues from their host plants in ant-plant systems, it is poorly demonstrated in ant gardens (AGs). In this interaction, ant species constantly interact with various epiphyte species. Therefore, it is possible to expect a convergence of chemical signals released by plants that could be acting to ensure that ants are able to recognize and defend epiphyte species frequently associated with AGs. In this study, it was hypothesized that ants recognize and differentiate among chemical stimuli released by AG epiphytes and non-AG epiphytes. We experimentally simulated leaf herbivore damage on three epiphyte species restricted to AGs and a locally abundant understory herb, Piper hispidum, in order to quantify the number of recruited Camponotus femoratus (Fabricius) defenders. When exposed to the AG epiphytes Peperomia macrostachya and Codonanthe uleana leaves, it was observed that the recruitment of C. femoratus workers was, on average, respectively 556% and 246% higher than control. However, the number of ants recruited by the AG epiphyte Markea longiflora or by the non-AG plant did not differ from paper pieces. This indicated that ants could discern between chemicals released by different plants, suggesting that ants can select better plants. These results can be explained by evolutionary process acting on both ants' capability in discerning plants' chemical compounds (innate attraction) or by ants' learning based on the epiphyte frequency in AGs (individual experience). To disentangle an innate behavior, a product of classical coevolutionary process, from an ant's learned behavior, is a complicated but important subject to understand in the evolution of ant-plant mutualisms.

New distribution record of Daceton boltoni Azorsa and Sosa-Calvo, 2008 (Insecta: Hymenoptera) in the Brazilian Amazon

The presence of Daceton boltoni in Cotriguaçu municipality, state of Mato Grosso, southern Amazon is reported. Workers of D. boltoni were collected manually in nests on the branches of three Caxeta trees (Simarouba amara Aubl. - Simaroubaceae) from a reforestation area. In the same location where D. boltoni was recorded, Daceton armigerum (Latreille 1802) workers have also been collected, corroborating the hypothesis that these are sympatric species. This is the first record of the occurrence of this species in Mato Grosso state and the second in the Brazilian Amazon.