A unique strategy of host colony exploitation in a parasitic ant: workers of Polyrhachis lama rear their brood in neighbouring host nests.

The formicine ant Polyrhachis lama is a social parasite, exploiting its ponerine host ant species Diacamma sp. In most social parasitic associations, the parasitic species are closely related to their host species group, evolving directly from independent ancestors of the host species. However, in the Polyrhachis lama- Diacamma sp. association, the associated species belong to different ant subfamilies. Based on preliminary field surveys, we had presumed that P. lama might have given up its reproductive division of labour, i.e. workers would be able to produce males as well as workers and females parthenogenetically. In this study, this hypothesis was disproved: Polyrhachis lama workers cannot be fertilized and are only able to produce males. In the host-parasite association originating from nests possessing a P. lama queen, workers penetrate surrounding Diacamma sp. nests, carrying brood for rearing within these satellite nests. In this peculiar way, a single P. lama colony is able to exploit several Diacamma sp. colonies simultaneously.

Molecular analysis of phylogenetic relationships among Myrmecophytic macaranga species (Euphorbiaceae).

Many species of the paleotropical pioneer tree genus Macaranga Thou. (Euphorbiaceae) live in association with ants. Various types of mutualistic interactions exist, ranging from the attraction of unspecific ant visitors to obligate myrmecophytism. In the latter, nesting space and food bodies are exchanged for protection by highly specific ant partners (mainly species of the myrmicine genus Crematogaster). As a first step toward elucidating the coevolution of ant-plant interactions in the Macaranga-Crematogaster system, we have initiated a molecular investigation of the plant partners' phylogeny. Nuclear ribosomal DNA internal transcribed spacer (ITS) sequences were analyzed for 73 accessions from 47 Macaranga species, representing 17 sections or informally described species groups. Three accessions from the putative sister taxon Mallotus Lour, were included as outgroups. Cladograms of the ITS data revealed Macaranga to be nested within Mallotus. ITS sequences are highly similar within section Pachystemon s.str., suggesting a relatively recent and rapid radiation of obligate myrmecophytes within this section. Forty-three accessions, mainly of ant-inhabited species, were additionally investigated by random amplified polymorphic DNA (RAPD) and microsatellite-primed PCR (MP-PCR) techniques. Phenetic analysis of RAPD and MP-PCR banding profiles generally confirmed the ITS results. Best resolutions for individual clades were obtained when ITS and RAPD/MP-PCR data were combined into a single matrix and analyzed phenetically. The combined analysis suggests multiple (four) rather than a single evolutionary origin of myrmecophytism, at least one reversal from obligate myrmecophytism to nonmyrmecophytism, and one loss of mutualistic specifity.

Communal peeing: a new mode of flood control in ants.

The behavioral response of the obligate bamboo-nesting ant Cataulacus muticus to nest flooding was studied in a perhumid tropical rainforest in Malaysia and in the laboratory. The hollow internodes of giant bamboo, in which C. muticus exclusively nests, are prone to flooding by heavy rains. The ants showed a two-graded response to flooding. During heavy rain workers block the nest entrances with their heads to reduce water influx. However, rainwater may still intrude into the nest chamber. The ants respond by drinking the water, leaving the nest and excreting water droplets on the outer stem surface. This cooperative 'peeing' behavior is a new survival mechanism adaptive to the ants' nesting ecology. Laboratory experiments conducted with two other Cataulacus species, C. catuvolcus colonizing small dead twigs and C. horridus inhabiting rotten wood, did not reveal any form of water-bailing behavior.

Chemical composition and function of metapleural gland secretion of the ant,Crematogaster deformis smith (hymenoptera: Myrmicinae).

The secretion of the hypertrophied metapleural gland of the antCrematogaster deformis contains a mixture of phenols, consisting mainly of 3-propylphenol, 3-pentylphenol, 3,4-dihydro-8-hydroxy-3-methylisocoumarin (mellein), 5-propylresorcinol, and 5-pentylresorcinol. The secretion is released, as a repellent, when the highly vulnerable petiolar-postpetiolar region of the abdomen is attacked by enemy ants. In addition, small amounts of the secretion are released regularly to serve as an antiseptic, which is considered the original function of the gland. The secretion also has some insecticidal properties.

Forage communication, nest moving recruitment, and prey specialization in the oriental ponerine Leptogenys chinensis.

In North Central Sri Lanka the ant Leptogenys chinensis specialises in feeding on fungus-growing Macrotermitinae (Odontotermes, Hypotermes), which are the commonest termites in this area. They are captured at their feeding sites. The ants recognize the termites by the scent that they emit. Workers and sexuals are the preferred prey. Termites of other taxa (Nasutitermitinae, Rhinotermitidae) are sometimes accepted and sometimes rejected. Refusal and acceptance are not correlated with the systematic position of the termites. Usually the nests of L. chinensis comprise 200-300 workers. Externally the female ergatoids do not differ from the workers. The ants live in naturally available cavities and move nests frequently. We investigated the communication of this species in relation to foraging and nest-moving. While foraging, single workers lay a light and nest-moving. While foraging, single workers lay a light exploration trail with venom. Successful scouts return to the nest and perform recruiting runs. Experiments with various blocked pheromone glands and decoys showed that the secretions of the poison gland and the Janet gland have to be applied to the ground. By this means groups of workers are recruited and led to a feeding place by a scout. When the scout was removed such groups would still, although slightly disturbed, find their way to the prey. Workers running alone are also observed. The secretion of the Janet gland has a recruiting effect, whereas the venom consists of two compounds: a compound of low volatility responsible for orientation, and a highly volatile compound which we interpret as being a way of estimating the age of the trail. In most cases, the recruited workers return singly to the nest. Retrieval of prey in groups is primarily observed with captured termite sexuals. Males use the trails to find and enter alien nests.In addition to the three chemical signals, stridulation with the gastral stridulatory organ is used as a mechanical signal in the frequent event of nest-moving. This induces general stridulation in the nest and initiates nest-moving, which is accomplished within a few minutes.

Individual trail marking by larvae of the scarce swallowtail Iphiclides podalirius L. (Lepidoptera; Papilionidae).

Starting from permanent resting sites covered with silk, the solitary and territorial larvae of I. podalirius spin silk trails leading to feeding sites. It is shown that the silk contains a volatile trail marker. The larvae recognize their own trails and prefer them to those laid by conspecific caterpillars. Trail marking appears to be widespread among larvae of Lepidoptera.

Zur jagdstrategie einiger orientalicher Leptogenys-arten (Formicidae: Ponerinae).

The sociobiology of Leptogenys ocellifera especially its predatory behavior and food recruitment was investigated. Leptogenys binghami and Leptogenys diminuta were observed comparatively. L. ocellifera: Colony size, nesting sites, and nest emigration. L. ocellifera lives in large colonies of several tens of thousands workers. It nests in existing soil cavities. The nesting site is changed in irregular intervals. According to our results the nest emigration is released by environmental factors.Trail system. There are several elaborated permanent routes leading from the nest into the surroundings. Those routes can be used continuously day and night over a period of several months. Guard ants are posting along the trails. Mainly in the evening, males were observed on the trails running back and forth. This behavior is interpreted as mating running". In the peripheral surroundings of the nest the routes may change within few hours or even minutes according to the food supply.Recruitment trails. The workers leave the nest singly or in groups. When an ant meets a prey animal it returns to the closest frequented trail rubbing its gaster tip on the ground while the sting is intermittendly extruded. The alarm secretion is released from the venom gland. It works as both orientation and recruiting signal and attracts new workers from the trail. No tactile signals are involved in food recruitment. The new workers in their turn intesify the alarm trail. Prey carrying workers lay trails to the nest which recruit further ants. Once the food source is exploited the alarm effect, even on strong trails, would decrease within half an hour. Recruitment trails which have been used over some time may become permanent routes. Along the permanent routes in addition to the recruiting substance an orientation component could be detected which lasts at least over 5 hrs. Its source is still unknownPredatory behavior. During foraging the workers frequently show digging behavior especially on places with fresh soil. Alarm secretion increases the digging activity. By this method L. ocellifera captures mainly animals which live in the soil, especially termites and earth worms. Other arthropods and snails are also predated. Larger prey objects are hunted and cut into pieces cooperatively. The pieces are transported into the nest by single workers. Killed termites are layed down near or on the trails by the foragers. Such depots are emptied by other workers. L. binghami and L. diminuta: L. binghami lives in natural earth cavities. It forages singly as a rule. Its main prey animals are termites. The trail secretion is mainly used during nest emigration. This is performed in a fast and well organized way. L. diminuta nests near the surface of the soil. It is a typical group prdator. The successful scouts lay recruiting trails while returning into the nest. The observed raids contained three to more than hundred workers led only sometimes by the scout. Prey objects (mainly larger arthropods) are hunted and retrieved cooperatively.

Tandem calling: a new kind of signal in ant communication.

Leptothorax acervorum, L. muscorum, and L. nylanderi recruit nest mates to a new food source by tandem running, with only one nest mate being recruited at a time. This technique is initiated by a special "tandem calling" behavior; the recruiter slants its gaster upward and discharges poison gland secretions from the extruded sting. Nest mates are attracted, and as soon as one of them touches the calling ant, tandem running starts. Further details of the full recruitment sequence are provided. Evidence is presented to suggest that tandem running is the evolutionary precursor of odor-trail communication and sex attraction within certain phylogenetic lines of myrmicine ants.