Maintenance of foraging trails by the giant tropical antParaponera clavata (Insecta: Formicidae: Ponerinae)

Summary Establishment and maintenance of foraging trails to an artificial nectar source by ten colonies ofParaponera davata (Fabr.) in Panama is reported. The first forager to locate the artificial nectar source was responsible for recruiting additional foragers and for marking trails to orient these foragers. More than half of the trail marking was performed by the first two ants to mark the path back to the colony, although up to 11 ants per colony per hour marked trails. The number of trail marks and the number of marking ants decreased through time, presumably as foragers learned the location of the artificial nectar source. Four categories of recruits were noted: markers, foragers, patrollers, and visitors.     

Multiple queens in founding colonies of the neotropical ant Pachycondyla striata Smith (Formicidae: Ponerinae)

In social insects, the typical mode of colony foundation occurs when a single queen is inseminated by a male and establishes a new colony, although we can find interspecific and intraspecific variations in queen number and queen-mating frequencies in a single colony. This study aimed to verify the queen number in Pachycondyla striata (Smith) colonies and to evaluate the level of aggressiveness among workers. We collected 14 colonies of P. striata. The behaviors of individuals from five multiple-queen colonies maintained in laboratory were studied by the method of scan sampling. In order to evaluate aggressiveness, dyadic encounters among heterocolonial and homocolonial workers were performed. The results showed that colonies of P. striata can have two or more mated queens (polygynous colonies) besides to monogynous ones (colony containing one queen). Because in polygynous colonies the number of workers was relatively low, such colonies could represent colonies in the foundation phase that characterize a pleometrosis state. In fact, ovarian development analysis from queens showed that the number of queens in the colonies seemed to be unstable. Despite a few cases of oophagy (egg cannibalism), social hierarchy among queens is unclear in comparison to other Pachycondyla species. In addition, aggressiveness increased with distance among nests. Nearby colonies (less than 1 m apart) showed a low level of aggressiveness, suggesting the presence of polydomy, that is, a unique colony can occupy multiple nests. Polygyny associated to polydomy in founding colonies may confer benefits on growth and dispersion of colonies in the studied environments.     

Communication in the primitive cryptobiotic ant Prionopelta amabilis (Hymenoptera: Formicidae)

Summary The Neotropical ant Prionopelta amabilis, a cryptobiotic species in the phylogenetically primitive tribe Amblyoponini, lives in subterranean habitats, where it preys preferentially on campodeid diplurans and other small arthropods. Here we report that the species employs chemical recruitment and orientation trails during foraging and nest emigrations. The trail pheromone originates in a hitherto unknown basitarsal gland located in the basitarsus of the hindlegs. Trails are laid by a special foot dragging behavior. During the recruitment process the chemical trail signal is complemented by body shaking on the part of the recruiting ant. Foragers frequently wipe the basitarsal gland opening in the hindlegs with the grooming apparatus of the front legs. This latter structure is equipped with unusual glands evidently specialized for this purpose.     

Nest architecture of Pachycondyla striata Fr. Smith, 1858 (Formicidae, Ponerinae)

Nine nests of Pachycondyla striata Fr. Smith, 1858 were excavated between 2006 and 2007 at the UNESP university campus in Rio Claro, SP, southeastern Brazil. The P. striata population was larger in the two nests excavated in the months of August and November, 2006. The nests of this species are simple and poorly elaborated, with chambers and tunnels close to the ground surface. P. striata places the pupae in chambers isolated from the other individuals. The lack of chambers with the specific purpose of conditioning food and garbage underscores the simplicity of these nests.     

Polyethism within hunters of the ponerine ant,Ectatomma ruidum Roger (Formicidae,Ponerinae)

Summary During laboratory experiments, two categories of prey-foraging workers were found inEctatomma ruidum: stingers and transporters. When numerous live drosophila were offered to the ants, one group of hunters specialized in killing the prey and another in transporting simultaneously the dead drosophila to the nest. Sometimes, there was a transfer of prey by a stinger towards a transporter, after an active soliciting of the transporter by antennation or by using the forelegs. We found high positive correlations between the colony size and the number of ants in each subcaste. A negative correlation existed between the colony size and the proportion of hunters. However, the proportion of workers in the two behavioral subcastes of hunters was stable in spite of differences in colony size. The phylogenetic interest of this type of cooperative predation is discussed.     

Samsum ant,Brachyponera sennaarensis (Formicidae: Ponerinae): Distribution and abundance in Saudi Arabia

Invasive species are capable of causing considerable damage to natural ecosystems, agriculture and economies throughout the World. Samsum ant, Brachyponera (Pachycondyla) sennaarensis has been a reason for medical implication and social nuisance through its poisonous and severely painful sting causing anaphylactic shock in many cases. We surveyed for the presence of the samsum ant in various provinces of Saudi Arabia. B. sennaarensis was the abundant Ponerinae species in human settlements. In the Eastern provinces, however, few samples were collected, and none were found in the Northern and Western provinces. Infestations of B. sennaarensis were particularly severe in the spring and summer seasons, when the ants make nests in moist areas and in cracks in cemented structures, whereas the extent of infestation reduced in winter seasons.     

Orientation and Communication in the Neotropical Ant Odontomachus bauri Emery (Hymenoptera,Formicidae, Ponerinae)

The Neotropical species Odontomachus bauri employs canopy orientation during foraging and homing. An artificial canopy pattern above the ants is much more effective as an orientation cue than horizontal landmarks or chemical marks. However, both horizontal visual cues and chemical marks on the ground can serve in localizing the nest entrance. Successful O. bauri foragers recruit nestmates to leave the nest and search for food. However, the recruitment signals do not contain directional information. Antennation bouts and pheromones from the pygidial gland most likely serve as stimulating recruitment signals. Secretions from the mandibular and poison gland elicit alarm and attack behavior.     

Diversity and morphology of abdominal glands in workers of the ant genus Myopias (Formicidae,Ponerinae)

Histological examination of serial sections through the abdomen of workers of three species of Myopias ants revealed the presence of several exocrine glands. These include the common venom and Dufour glands as well as the pygidial gland, but also more specific sternal glands and glands associated with the sting base and the gonostyli. Two of these glands have not been reported previously among ants: one is the paired oblong plate gland, that occurs next to the oblong plate and may have a pheromonal function. The other novel gland is the paired sting shaft gland, that occurs at the dorsal side in the proximal region of the sting shaft. A remarkable characteristic of these Myopias ants is that all glands of class-3 show ducts with gradually widening internal diameter. Myopias emeryi shows a clearly more simple variety of abdominal glands than Myopias maligna and M. sp.1.     

The ant subfamilies Ponerinae,Cerapachyinae, and Pseudomyrmecinae (Hymenoptera,Formicidae) in the Late Eocene ambers of Europe

The ant subfamilies Ponerinae, Cerapachyinae and Pseudomyrmecinae are revised in the Baltic, Bitterfeld, Rovno, and Scandinavian ambers of the Late Eocene age. Thirteen new species are described: Amblyopone groehni sp. n., A. electrina sp. n., Pachycondyla conservata sp. n., P. tristis sp. n., Ponera lobulifera sp. n., P. mayri sp. n., P. wheeleri sp. n., Gnamptogenys rohdendorfi sp. n., Bradoponera similis sp. n., Proceratium eocenicum sp. n. (Ponerinae), Procerapachys sulcatus sp. n. (Cerapachyinae), Tetraponera europaea sp. n., and T. groehni sp. n. (Pseudomyrmecinae). Tetraponera angustata (Mayr) is synonymized with T. simplex (Mayr). Keys to species are provided.     

Development of the labial gland of the ponerine ant Pachycondyla obscuricornis (Hymenoptera, Formicidae) during the pupal stage

The labial gland of adult workers of the ant Pachycondyla obscuricornis is made up of many acini, each consisting of one central cell surrounded by approximately 10 parietal cells. Both cell types are associated with a system of ramified canaliculi that remove the secretion towards a ductule outside the acinus. These ductules, each associated with one acinus, fuse together and form a ramified system of ducts, ending in two paired ducts. These paired ducts widen to form a reservoir and anteriorly join into a common unpaired duct, which ends at the base of the labium. During development in the pupal stage, epithelial acini are formed first, consisting of a monolayered epithelium lining a central lumen. In these acini, one cell grows out to become the central cell, while the others will re-arrange around it to form the parietal cells. At the end of the pupal stage, the canaliculi are formed inside the acini by the central and parietal cells that secrete a lipidic substance and a cuticle. This gland type, which also occurs in some other Hymenoptera, is structurally different from the epithelial glands and the glands consisting of bicellular units, that have been traditionally distinguished until now.     

The significance of visual landmarks for navigation of the giant tropical ant,Paraponera clavata (Formicidae,Ponerinae)

Summary Workers of the giant tropical ant,Paraponera clavata, use trail pheromones for orientation and recruitment of nestmates. However, chemical markings may not always be sufficient for successful navigation in complex three-dimensional terrain, and additional orientation cues may be required. Behavioral field experiments were performed to investigate the significance of visual landmarks for homing foragers. Animals which were prevented from seeing the canopy were unable to navigate back to the nest, even though trail pheromones were still present. In contrast, foragers found their way back to the nest after their trail pheromones had been abolished but their visual scenes remained unchanged. This emphasizes the important role of visual landmarks during spatial orientation in homingP. clavata foragers. Individually foraging scouts were discovered in the understory of the forest floor up to 30 m away from their nest. They were rewarded, and displaced between 0.8 m and 13.6 m. Fifteen out of 16 animals had no difficulties in finding the nest entrance despite the altered appearance of local and distant landmarks at the release site. Apparently the scouts were able to recognize the visual scenes at the release site, and used them for reference to locate the nest entrance. In contrast, ants displaced from their nest to sites around 4 m away had more difficulties to re-find the nest.     

The antimicrobial activity of the mandibular gland secretion of a formicine ant, Calomyrmex sp. (Hymenoptera: Formicidae)

The mandibular gland secretion from mature workers of the formicine ant Calomyrmex sp. exhibits strong antimicrobial activity when tested against selected soil microorganisms. The activity against bacteria is both inhibitory and bacteriocidal while that against fungi is inhibitory. The white secretion from young workers appears to be much weaker in its antibiotic effects.     

Polymorphism and oligogyny in the ponerine antCentromyrmex bequaerti (Formicidae: Ponerinae)

Summary Centromyrmex bequaerti is a ponerine ant of the African equatorial forest which nests in the termitaries of diverse Termitinae and Macrotermitinae, occupying several chambers and galleries of the termitaries and preying on their guests. This species presents four traits convergent with termitolestic Myrmicinae: a parasitic nesting habit (but shelters directly in the cavities of the termitaries and not in the walls), blind workers, a strong dimorphism between the queens (20 mm in length) and the workers (from 5.75 to 12 mm total length) and polymorphism in the worker caste. We recorded two other traits considered as evolutionarily-derived: oligogyny, a kind of polygyny (the societies include up to 13 queens, but each queen lives in a separate cavity of the termitary) and large colon size. Behavioural observations show that there is a relationship between worker size and polyethism in this species. Although workers of all size classes participate in hunting, the media are more often engaged in this activity and the largest workers guard the nest entrance.     

Gamergate reproduction in the antStreblognathus aethiopicus Smith (Hymenoptera: Formicidae: Ponerinae)

Summary We examined morphological and behavioral features of the reproductive biology of the ponerine ant,Streblognathus aethiopicus. Investigation of the ant's ovaries and spermathecae showed that each colony had a single reproductive (= gamergate). Morphologically this individual could not be distinguished from her nestmates, while the only clear-cut behavioural difference between the gamergate and workers was that the former laid eggs. Experimental removal of the gamergate from colonies resulted in the enlargement of the ovaries in some of the workers. This appears to show that the reproductive is able to suppress reproductive activity of her nestmates.

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Fortpflanzung dürch Gamergaten bei Streblognathus aethiopicus Smith (Hymenoptera: Formicidae: Ponerinae)

Zusammenfassung Wir untersuchten Aspekte der Morphologie und des Verhaltens der Fortpflanzungsbiologie beiStreblognathus aethiopicus (Unterfamilie Ponerinae). Die Untersuchung der Ovarien und Spermatheken zeigte, daß jede Kolonie über eine einzige Gamergate verfügte. Dieses Individuum konnte morphologisch nicht von seinen Nestgenossen unterschieden werden. Auch im Verhalten kann sie nur durch das Eierlegen erkann werden. Wurde die Gamergate im Experiment aus der Kolonie entfernt, vergrößerten sich bei einigen der Arbeiterinnen die Ovariolen. Demzufolge kann die Gamergate die Fortpflanzungsaktivität der Nestgenossen unterdrücken.