New record of the Ponerine ant Buniapone amblyops (Emery, 1887) (Hymenoptera: Formicidae) from Nepal

Buniapone Schmidt & Shattuck 2014 is a monotypic and morphologically distinct hypogeic ant genus found only in Southern and Southeast Asia. The Ponerine ant Buniapone amblyops (Emery 1887) has been recorded for the first time from Nepal. The specimen was hand-collected in Pokhara (28.21361111 N, 83.97222222 E, 840 m asl) from animal dung on the ground. Morphological characteristics of Nepalese B. amblyops worker, distribution, and ecology are discussed.

Prey Status Affects Paralysis Investment in the Ponerine Ant Harpegnathos venator

The paralysis behavior of some ponerine ants when foraging may be important for food storage and colony development. However, how workers invest in paralysis under different prey circumstances is often overlooked. Here, we report the prey-foraging behavior and paralysis behavior of Harpegnathos venator under different food supply conditions. Solitary hunting was the main foraging mode of H. venator, with occasional simple collective hunting. Nymphal cockroaches with high activity were the most attractive to H. venator. In the experiment, we found that the stings of H. venator completely paralyzed the cockroaches. The stinging time was significantly longer at a higher prey activity level and for larger cockroaches. In addition, there was no significant difference in the stinging time of H. venator for different prey densities. The results showed that the longer similar cockroaches were stung, the longer it took for them to revive and move. These results are helpful for further understanding the behavioral mechanism underlying the food storage of live prey by predatory insects.

A new ant-butterfly symbiosis in the forest canopy fills an evolutionary gap

Myrmecophilous butterflies can establish complex symbiotic relationships with ants. A caterpillar wandering among the brood of the aggressive ponerine ant Neoponera villosa was found inside the core of a nest built in the myrmecophytic bromeliad Aechmea bracteata. This is the first caterpillar found living inside a ponerine ant nest. Its DNA barcode was sequenced, and an integrative approach was used to identify it as Pseudonymphidia agave, a poorly known member of the subtribe Pachythonina in the riodinid tribe Nymphidiini. The cuticle of the tank-like caterpillar lacks projections or tubercles and is covered dorsally by specialized flat setae that form an armor of small plates. Ant-organs potentially related to caterpillar-ant signaling, such as perforated cupola organs and tentacle nectary organs, are present. These morphological traits, together with evidence of social integration (direct contact with host brood, protective morphology, slow movement, no host aggressiveness), suggest that P. agave is a symbiotic, social parasite of N. villosa, preying on its host brood. However, several knowledge gaps remain, including oviposition site, dependence on bromeliad association, steps to colony integration, and larval diet through development. Carnivory has been reported in all known members of the subtribe Pachythonina (caterpillars prey on honeydew-producing hemipterans) suggesting a shift to myrmecophagy inside the ant nests as a possible evolutionary transition.

Loss of wings induces the expression of the worker-like phenotype in queens of a ponerine ant

Many highly-eusocial insect species are characterized by morphological differences between females. This is especially pronounced in ants where queens usually possess a fully developed thorax with wings and are specialized for reproduction while workers have a reduced thorax without wings and show various levels of reproductive degeneration that is associated with their helper role in the colony. Despite their morphological differentiation, queens and workers still show some plasticity leading to overlapping behavioral and physiological phenotypes. We investigated the level of queen plasticity and the factor that induces a worker-like phenotype in the ant species Harpegnathos saltator that has limited queen-worker dimorphism and workers that can assume the reproductive role of a queen in the colony. By comparing alate and dealate young queens, so-called gynes, we found that the loss of wings initiated the expression of behavioral and physiological characteristics of ant workers. In contrast to alate gynes, dealate gynes displayed higher frequencies of worker-like behaviors. In addition, dealate gynes showed a worker-like range of reproductive states unlike alate gynes. Like workers, dealate gynes lost the chemical signaling that is characteristic of alate gynes. Since gynes can activate this worker-like phenotype after wing loss, the essential difference between the ant queens and workers in this species with limited queen-worker dimorphism is a dispersal polyphenism. If the phenotypic plasticity observed in H. saltator is representative of the early stages of ant eusociality, an emerging dispersal dimorphism rather than a distinct reproductive dimorphism might represent one of the first steps in ant evolution.

Filling the gap: a new ant-butterfly symbiosis in the forest canopy

Myrmecophilous butterflies can establish complex symbiotic relationships with ants. An elusive symbiotic caterpillar wandering among the brood of the aggressive ponerine ant, Neoponera villosa, was found inside the core of a nest built in the myrmecophytic bromeliad Aechmea bracteata. This is the first caterpillar found in symbiosis with a species of the subfamily Ponerinae. Tissue sample was barcoded, and an integrative approach was used to identify it as Pseudonymphidia agave, a poorly known Pachythonina member in the riodinid myrmecophilous tribe Nymphidiini. The caterpillar has a general tank-like body morphology, without projections or tubercles, and is covered dorsally by specialized flat setae that form an armor of small plates. Ant-organs potentially related to the caterpillar-ant signaling, such as perforated cupola organs and tentacle nectary organs, are present. These functional traits, together with the stable social integration, suggest that P. agave is a specialized social parasite of N. villosa. However, several knowledge gaps remain, notably the oviposition site, dependence on bromeliad association, steps to colony integration, and the larval diet through ontogeny. Carnivory has been reported in all known members of the Pachythonina subtribe (caterpillars prey on honeydew-producing hemipterans), and a shift to myrmecophagy inside the ant nests is a possible evolutionary step.

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.

Bacterial Composition and Diversity of the Digestive Tract of Odontomachus monticola Emery and Ectomomyrmex javanus Mayr

Ponerine ants are generalist predators feeding on a variety of small arthropods, annelids, and isopods; however, knowledge of their bacterial communities is rather limited. This study investigated the bacterial composition and diversity in the digestive tract (different gut sections and the infrabuccal pockets (IBPs)) of two ponerine ant species (Odontomachus monticola Emery and Ectomomyrmex javanus Mayr) distributed in northwestern China using high-throughput sequencing. We found that several dominant bacteria that exist in other predatory ants were also detected in these two ponerine ant species, including Wolbachia, Mesoplasma, and Spiroplasma. Bacterial communities of these two ant species were differed significantly from each other, and significant differences were also observed across their colonies, showing distinctive inter-colony characteristics. Moreover, bacterial communities between the gut sections (crops, midguts, and hindguts) of workers were highly similar within colony, but they were clearly different from those in IBPs. Further, bacterial communities in the larvae of O. monticola were similar to those in the IBPs of workers, but significantly different from those in gut sections. We presume that the bacterial composition and diversity in ponerine ants are related to their social behavior and feeding habits, and bacterial communities in the IBPs may play a potential role in their social life.

The first representative of the trap-jaw ant genus Anochetus Mayr, 1861 in Neogene amber from Sumatra(Hymenoptera: Formicidae)

The ponerine ant Anochetus miosumatrensis Ngô-Muller, Garrouste & Nel, n. sp. is described from a fossil alate female preserved in amber of Sumatra which is reputedly of Miocene age. On the basis of the general morphology, the fossil could be attributed to the extant Sumatran species group risii Brown, 1978. By comparing with the living environment of the extant species, this ant probably lived in a warm humid forest where it was trapped in dipterocarpacean resin during nuptial flight. Until now, the known Cenozoic distribution of the genus Anochetus was restricted to the Neotropical region. Thus A. miosumatrensis Ngô-Muller, Garrouste & Nel, n. sp. brings the first record of the genus from Indomalaya biogeographic region.

Nest Site Selection during Colony Relocation in Yucatan Peninsula Populations of the Ponerine Ants Neoponera villosa (Hymenoptera: Formicidae)

In the Yucatan Peninsula, the ponerine ant Neoponera villosa nests almost exclusively in tank bromeliads, Aechmea bracteata. In this study, we aimed to determine the factors influencing nest site selection during nest relocation which is regularly promoted by hurricanes in this area. Using ants with and without previous experience of Ae. bracteata, we tested their preference for refuges consisting of Ae. bracteata leaves over two other bromeliads, Ae. bromeliifolia and Ananas comosus. We further evaluated bromeliad-associated traits that could influence nest site selection (form and size). Workers with and without previous contact with Ae. bracteata significantly preferred this species over others, suggesting the existence of an innate attraction to this bromeliad. However, preference was not influenced by previous contact with Ae. bracteata. Workers easily discriminated between shelters of Ae. bracteata and A. comosus, but not those of the closely related Ae. bromeliifolia. In marked contrast, ants discriminated between similar sized Ae. bracteata and Ae. bromeliifolia plants, suggesting that chemical cues and plant structure play an important role. Size was also significant as they selected the largest plant when provided two dissimilar Ae. bracteata plants. Nest site selection by N. villosa workers seems to depend on innate preferences but familiarization with plant stimuli is not excluded.