Do Odontomachus brunneus nestmates request for help and are taken care of when caught?

In social insects, situations can arise that threaten an individual or an entire colony. When the call for help goes out, different behavioral responses are elicited by signals emitted from nestmates. In ants, the response can be one of redemptive behavior by the worker receiving it. However, little is known about the evolution of this behavior and in which group of ants it manifests. Therefore, this study investigates whether workers of Odontomachus brunneus Patton can act as rescuers, able to detect and respond to calls for help from nestmates. Laboratory experiments were carried out in which the legs of ants were trapped by tape, simulating capture by a predator. Nearby were nestmates able to receive and respond to a request for help. Two experiments were performed: 1. Calls for help were made at different distances, in order to test the response latency. 2. Evaluation of whether rescuers would respond differently to calls for help from nestmates, non-nestmates of the same species, and ants of another species. Finally, evaluation was made of the behaviors of the rescuers when they responded to requests for help from nestmates and ants of another species. It could be concluded from the results that O. brunneus workers respond to signals emitted by workers who may have been captured by a potential predator, prompting the performance of behaviors related to rescue attempts. The signals involved appear to have an optimal range and are species-specific. When exposed to a capture situation, this species transmits audible signals by stridulation, so it is possible that this type of signal may be involved, in addition to chemical signaling.

Green Anole lizards (Anolis carolinensis) deposit eggs in nests of the Trap Jaw Ant, Odontomachus brunneus

Squamates eggs are rarely found in ant nests, and are largely restricted to the nests of neotropical fungus gardening in the tribe Attini. Ponerine ant nests have not previously been reported as nesting cavities for squamates, including the Green Anole (Anolis carolinensis). The current study reports the association of Green Anole eggs and hatchlings with the subterranean nest chambers of the trap jaw ant, Odontomachus brunneus. Hatching rates suggest that O. brunneus nests may be used communally by multiple females, which partition spatial resources with other recently introduced Anolis species in their native range. This new nesting strategy is placed in the context of know associations between frogs, snakes, legless worm lizards and ants.

Pendulum-based measurements reveal impact dynamics at the scale of a trap-jaw ant

Small organisms can produce powerful, sub-millisecond impacts by moving tiny structures at high accelerations. We developed and validated a pendulum device to measure the impact energetics of microgram-sized trap-jaw ant mandibles accelerated against targets at 105 m s−2. Trap-jaw ants (Odontomachus brunneus; 19 individuals; 212 strikes) were suspended on one pendulum and struck swappable targets that were either attached to an opposing pendulum or fixed in place. Mean post-impact kinetic energy (energy from strike converted to pendulum motion) was higher with a stiff target (21.0-21.5 µJ) than a compliant target (6.4-6.5 µJ). Target mobility had relatively little influence on energy transfer. Mean contact duration of strikes against stiff targets was shorter (3.9-4.5 ms) than against compliant targets (6.2-7.9 ms). Shorter contact duration was correlated with higher post-impact kinetic energy. These findings contextualize and provide an energetic explanation for the diverse, natural uses of trap-jaw ant strikes such as impaling prey, launching away threats, and performing mandible-powered jumps. The strong effect of target material on energetic exchange suggests material interactions as an avenue for tuning performance of small, high acceleration impacts. Our device offers a foundation for novel research into the ecomechanics and evolution of tiny biological impacts and their application in synthetic systems.

Bacterial Communities in the Midgut of Ponerine Ants (Hymenoptera: Formicidae: Ponerinae)

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, Pachycondyla curvinodis, Pachycondyla striata, Odontomachus brunneus and Odontomachus bauri. After dissecting the midguts of these ants, DNA was extracted, and the bacterial 16S rRNA gene was amplified via PCR using the universal primers pair 27F/1492R. The obtained PCR products were cloned and sequenced using an ABI 3500 automated sequencer. The sequences were grouped into operational taxonomic units (OTUs) based on a 97% similarity criterion using MOTHUR. 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 P. 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. 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 for immunity, reproduction and nutrition; moreover, a subset may be parasites that have considerable impacts on the studied ants.

A social insect fertility signal is dependent on chemical context

Identifying group members and individuals' status within a group are fundamental tasks in animal societies. For ants, this information is coded in the cuticular hydrocarbon profile. We manipulated profiles of the ant Odontomachus brunneus to examine whether the releaser and primer effects of fertility signals are dependent on chemical context. Fertility status is signalled through increased abundance of ( Z )-9-nonacosene ( Z 9 : C 29 ). Across the ant's distribution, populations have distinct hydrocarbon profiles but the fertility signal is conserved. Foreign queens and fertility-signal-treated workers from the same population, sharing a similar chemical background, elicited releaser effects from workers, whereas queens and fertility-signal-treated workers from different populations did not. Z 9 : C 29 presented without chemical background did not elicit releaser effects. A primer-effect experiment found that Z 9 : C 29 , presented without a chemical background, did not inhibit worker reproduction. Our results demonstrate that a familiar chemical background is necessary for appropriate responses to fertility signals.