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Upon falling onto the water surface, most terrestrial arthropods helplessly struggle and are quickly eaten by aquatic predators. Exceptions to this outcome mostly occur among riparian taxa that escape by walking or swimming at the water surface. Here we document sustained, directional, neustonic locomotion (i.e. surface swimming) in tropical arboreal ants. We dropped 35 species of ants into natural and artificial aquatic settings in Peru and Panama to assess their swimming ability. Ten species showed directed surface swimming at speeds >3 body lengths s−1, with some swimming at absolute speeds >10 cm s−1. Ten other species exhibited partial swimming ability characterized by relatively slow but directed movement. The remaining species showed no locomotory control at the surface. The phylogenetic distribution of swimming among ant genera indicates parallel evolution and a trend toward negative association with directed aerial descent behavior. Experiments with workers of Odontomachus bauri showed that they escape from the water by directing their swimming toward dark emergent objects (i.e. skototaxis). Analyses of high-speed video images indicate that Pachycondyla spp. and O. bauri use a modified alternating tripod gait when swimming; they generate thrust at the water surface via synchronized treading and rowing motions of the contralateral fore and mid legs, respectively, while the hind legs provide roll stability. These results expand the list of facultatively neustonic terrestrial taxa to include various species of tropical arboreal ants.

Made available in DSpace on 2018-12-11T16:42:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-03-01 Symbiotic microorganisms are directly related to the ecological success of host insects, influencing many aspects of their biology. The present study is the first to investigate the microbiota associated with ants of the subfamily Ponerinae and aims to identify the bacterial midgut communities of Dinoponera lucida, Neoponera curvinodis, Pachycondyla striata, Odontomachus brunneus and Odontomachus bauri relied on culture-dependent technique, particularly 16S rRNA sequencing. The greatest species richness was observed in O. bauri, with 15 OTUs, followed by D. lucida with five OTUs, O. brunneus, with four OTUs, and N. curvinodis and P. striata, both with three OTUs. There were representatives of the phyla Actinobacteria, Proteobacteria, Tenericutes and Firmicutes, including the genera Bartonella, Mesoplasma, Mesorhizobium, Spiroplasma, Wolbachia and Serratia in the guts of the studied Ponerine ants. Spiroplasma and Mesoplasma were found to be prevalent in the studied ants and they were the only genera of bacteria found in more than one of the analyzed ant species suggesting they might be beneficial symbionts. The low microbial diversity observed given the predatory trophic habits of the species studied suggests that there is selection for these microorganisms, predominantly preserving symbionts with functional roles that are able to colonize this environment. It is also valid to infer that the identified bacteria are predominant in the gut and exhibit mutualistic functions that are important mainly for immunity, but also to reproduction and nutrition; moreover, a subset may be parasites that could have considerable impacts on the studied ants. Universidade Estadual de Santa Cruz Departamento de Ciências Biológicas Laboratório de Microbiologia, Rodovia Jorge Amado, Km 16, Salobrinho Universidade Estadual Paulista (UNESP) Universidade Federal do Tocantins (UFT) UESC Laboratório de Mirmecologia CEPLAC Universidade Estadual Paulista (UNESP)

The interactions of the antOdontomachus bauriwith nymphs of the sap-sucking bugXedreota tuberculata(Cicadellidae: Ledrinae) were studied onSipaneaaff. (Rubiaceae) along a trail in an upland forest in the Ecological Reserve of Anavilhanas, AM, Brazil. Five complete interactions at day and at night (about 60 minutes) were analyzed. The care of cicadelid nymphs ranged between 12 and 961 seconds.

We conducted ultrastructural studies to examine the presence of microorganisms in the midgut of the ant Odontomachus bauri (Ponerinae), as a contribution towards understanding the relationships between microorganisms and their hosts. The presence of microorganisms in this region, including inside the cells, suggests their participation in food digestion as symbiontic organisms and represent a new possibility to exploit food sources in the environment.

Extreme animal movements are usually associated with a single, high-performance behavior. However, the remarkably rapid mandible strikes of the trap-jaw ant, Odontomachus bauri , can yield multiple functional outcomes. Here we investigate the biomechanics of mandible strikes in O. bauri and find that the extreme mandible movements serve two distinct functions: predation and propulsion. During predatory strikes, O. bauri mandibles close at speeds ranging from 35 to 64 m·s −1 within an average duration of 0.13 ms, far surpassing the speeds of other documented ballistic predatory appendages in the animal kingdom. The high speeds of the mandibles assist in capturing prey, while the extreme accelerations result in instantaneous mandible strike forces that can exceed 300 times the ant’s body weight. Consequently, an O. bauri mandible strike directed against the substrate produces sufficient propulsive power to launch the ant into the air. Changing head orientation and strike surfaces allow O. bauri to use the trap-jaw mechanism to capture prey, eject intruders, or jump to safety. This use of a single, simple mechanical system to generate a suite of profoundly different behavioral functions offers insights into the morphological origins of novelties in feeding and locomotion.

About 85 different ant species were found nesting on coconut palms in Malaysia, the Philippines, Sri Lanka, Tanzania and Trinidad. Three occurred in all countries. With the exception of the leaf-nesting Oecophylla spp, all nested in leaf axils and spadices mostly between the two sheaths (spathes) and peduncle of the spadix. Up to eight species were found nesting in the same palm and five in the same spadix. In the latter circumstances the nest distribution of different non-dominant species is initially associated with the ‘height’ of available spaces, the smaller species nesting in the narrower, more distal end and the larger in the proximal end of the spadix. However, the small dominants, Pheidole spp and Wasmannia auropunctata, initially choose the large spaces in ageing spadices and leaf axils. In the spatially simple leaf axil the most striking association was between the small dominant Wasmannia auropunctata and the large ponerine Odontomachus bauri with W. auropunctata nesting below and between gall...

Measurements of oxygen consumption from ant colonies of various sizes of Odontomachus bauri, Camponotus rufipes and Zacryptocerus depressus showed a complex and nonlinear relationship between colony size and energy consumption per unit mass. Results show that at certain critical colony sizes, the colonies energy consumption is larger than the sum of the average energy requirement of the individually workers, and near maximal colony sizes, the energy consumption of the colony per unit mass tends exponentially to that of the average individual worker. We propose that social complexity is related to energy consumption in a discontinuous manner and is bound by both, negentropy content of a society and social optimization mechanisms.

SUMMARYTrap-jaw ants of the genus Odontomachus produce remarkably fast predatory strikes. The closing mandibles of Odontomachus bauri, for example, can reach speeds of over 60 m s–1. They use these jaw strikes for both prey capture and locomotion – by striking hard surfaces, they can launch themselves into the air. We tested the hypothesis that morphological variation across the genus is correlated with differences in jaw speeds and accelerations. We video-recorded jaw-strikes at 70 000–100 000 frames s–1 to measure these parameters and to model force production. Differences in mean speeds ranged from 35.9±7.7 m s–1 for O. chelifer, to 48.8±8.9 m s–1 for O. clarus desertorum. Differences in species' accelerations and jaw sizes resulted in maximum strike forces in the largest ants (O. chelifer) that were four times those generated by the smallest ants (O. ruginodis). To evaluate phylogenetic effects and make statistically valid comparisons, we developed a phylogeny of all sampled Odontomachus species and seven outgroup species (19 species total) using four genetic loci. Jaw acceleration and jaw-scaling factors showed significant phylogenetic non-independence, whereas jaw speed and force did not. Independent contrast (IC) values were used to calculate scaling relationships for jaw length, jaw mass and body mass, which did not deviate significantly from isometry. IC regression of angular acceleration and body size show an inverse relationship, but combined with the isometric increase in jaw length and mass results in greater maximum strike forces for the largest Odontomachus species. Relatively small differences (3%) between IC and species-mean based models suggest that any deviation from isometry in species' force production may be the result of recent selective evolution, rather than deep phylogenetic signal.

Gorgona is one of the two insular areas of the Colombian tropical rain forest at the Pacific and is amongst the most diverse biogeographic regions of the world, the Choco. This study compiles information on ant species from published (1991) and unpublished (2006) studies and provides new records for ant species collected in 2010. Ants were sampled and information was obtained from 15 sites in Gorgona island (13.82km2), including the Gorgonilla atoll (0.49km2). Collecting methods included pitfall traps, tuna baits, mini-Winkler extraction of leaf litter, Malaise traps, entomological net and direct search. The soil and understory ant inventory resulted in 107 ant species and morphospecies, 46 genera in 12 subfamilies. Myrmicinae held the highest species richness (37 species), followed by Ponerinae (27) and Formicinae (12). The richest genera were Pachycondyla (15 species), Camponotus (nine) and Pheidole (eight), while 30 genera were represented by a single species. Twelve species were very common (both in distribution and time): Azteca sp., Atta cephalotes, Camponotus sericeiventris, Eciton vagans, Ectatomma goninion, Gnamptogenys annulata, Odontomachus bauri, Pachycondyla bugabensis, P. harpax, P. verenae, Paraponera clavata and Wasmannia auropunctata. Direct search was the most efficient method to collect diferent species and was responsible for 52% of the total species found. Compared to other Neotropical islands, Gorgona holds a suprisingly high number of ant species, none of them invasive. The invasive Monomorium floricola, which was collected 20 years ago, was not found in 2010. These evidences suggest that ecological mechanisms and natural recovery processes in the ecosystem have generated microhabitats allowing their coexistence. Rev. Biol. Trop. 62 (Suppl. 1): 265-276. Epub 2014 February 01.

Foraging behavior and partitioning of foraging areas ofOdonomachus bauriwere investigated on Barro Colorado Island in Panama. The activity of the ants did not show any daily pattern; foragers were active day and night. The type of prey captured byO. baurisupports the idea that in higherOdontomachusand Anochetus species, the high speed of mandible closure serves more for generating power than capturing elusive prey. Polydomous nests may enableO. bauricolonies to enlarge their foraging areas.

Odontomachus bauri workers recognize conspecifics from other colonies and ants from different species as aliens. Colony specific recognition is based on endogenous odours, present in the different body parts. The chemicals responsible for these odours are volatiles, insoluble in water and soluble in CH2Cl2. No influence of the environment on the recognition signals could be detected. Evidence of intercolony differences in the relative proportions of the different volatile substances of cephalic and abdominal pheromones are presented. Thus, it is postulated that nestmate recognition is based on relative proportions of volatiles produced by the ant in different parts of the body. On the other hand, evidence of territorial defence is presented. Territorial pheromones, in case they exist in this species, are not necessary for recognition of territories, as is the case in other ant species. The possible relationship between nestmate recognition systems and territorial behaviour is discussed and an evolutionary hypothesis of their development is presented.