Slave Species Research Articles

Physiology Is Destiny: The Fate of Eugenic Utopia in the Fiction of H. P. Lovecraft and Olaf Stapledon

ABSTRACT Lovecraft and Stapledon imagined alien societies as utopias whose order and destiny derive from their citizens' eugenically altered physiologies. Stapledon's focus on eugenics as a means for achieving utopia during the interwar period is well known, but Lovecraft's worldview is generally understood to be dysgenic and dystopian in its obsession with racial and cultural degeneration. Lovecraft's fullest depiction of an alien civilization, the Old Ones in At the Mountains of Madness, relies upon a eugenic prehistory that is never explicitly narrated. The Old Ones' implicitly eugenic origin accounts for the utopian features of their society but also foreshadows their fall to their genetically engineered slave species, the shoggoths, which supplant their creators through their superior adaptability. The failure of the Old Ones' eugenics of homogeneity contrasts with the triumph of the eugenic project of diversification pursued by the Symbiotic civilization, which leads the cosmos to utopia in Stapledon's Star Maker.

Morphometrics, life history and population biology of the Ponto-Caucasian slave-making ant Myrmoxenus tamarae (Hymenoptera: Formicidae)

The ant genus Myrmoxenus consists of about ten socially parasitic species including active slave-makers and workerless degenerate slave-makers. Myrmoxenus tamarae was previously known only from type material, two workers collected at Daba, Georgia and nothing was known about its life history, colony structure or the morphology of its sexuals. An inspection of colonies of M. tamarae near the type locality in 2010 indicates that young queens of M. tamarae invade Temnothorax nests and kill the host queen by throttling. The simultaneous presence of two slave species in a single colony (an undescribed species related to T. nylanderi and a species morphologically resembling T. unifasciatus) indicates that M. tamarae is an active slave-maker. The genetic structure of the colonies matches that expected for a monogynous and monandrous ant, but three of eight colonies inspected appeared to contain work- ers belonging to an additional genetic lineage.

Incomplete homogenization of chemical recognition labels between Formica sanguinea and Formica rufa ants (Hymenoptera: Formicidae) living in a mixed colony.

Formica sanguinea Latreille (Hymenoptera: Formicidae) is a slave-making species, i.e., it raids colonies of host species and pillages pupae, which are taken to develop into adult workers in a parasite colony. However, it has been unclear if the coexistence of F. sanguinea with slave workers requires uniformity of cuticular hydrocarbons (CHCs), among which those other than n -alkanes are believed to be the principal nestmate recognition cues utilized by ants. In this study, a mixed colony (MC) of F. sanguinea and Formica rufa L. as a slave species was used to test the hypothesis that CHCs are exchanged between the species. Chemical analysis of hexane extracts from ants’ body surfaces provided evidence for interspecific exchange of alkenes and methyl-branched alkanes. This result was confirmed by behavioral tests during which ants exhibited hostility toward conspecific individuals from the MC but not toward ones from homospecific colonies of their own species. However, it seems that species-specific differences in chemical recognition labels were not eliminated completely because ants from the MC were treated differently depending on whether they were con- or allospecific to the individuals whose behavioral reactions were tested. These findings are discussed in the context of mechanisms of colony's odor formation and effective integration of slaves into parasite colony.

Indirect Effects in Boreal Ant Assemblages: Territorial Wood Ants Protect Potential Slaves Against Enslaving Ants

Abstract. The facultative enslaver Formica sanguinea Latr. uses as slaves F. fusca L. and other species of the subgenus Serviformica For. Earlier observations have shown or suggested that strong territorial wood-ant species, by defending their own territories, interfere with raids by F. sanguinea such that colonies of potential slave species gain protection against raids. At the population level, such protection should be visible as higher nest densities of F. fusca within than outside wood-ant territories, when both areas are within raiding distance of F. sanguinea. Here we tested this hypothesis by mapping nest densities of F. fusca. As expected, nest densities of F. fusca were higher within than outside wood-ant territories. In contrast, nest densities of two aggressive species, Lasius platythorax Seifert and L. niger (L.), unsuitable as slaves, were as expected lower within than outside wood-ant territories. Our results concur with earlier studies based on pitfall trapping, baiting experiments, and in...

A chemical level in the coevolutionary arms race between an ant social parasite and its hosts

Here we investigate the coevolutionary interactions between the slavemaking ant Protomognathus americanus and its Temnothorax hosts on a chemical level. We show that, although this social parasite is principally well-adapted to its hosts' cuticular hydrocarbon profile, there are pronounced differences in the fine-tuning of this adaptation. Between populations, chemical adaptation varies with host community composition, as the parasite faces a trade-off when confronted with more than one host species. In addition to adaptation of its own chemical signature, the slavemaker causes a reciprocal adjustment in its slaves' cuticular profile, the degree of which depends on the slave species. On the host side, successful parasite defence requires efficient enemy recognition, and in behavioural aggression trials, host colonies could indeed discriminate between invading slaves, which commonly accompany slavemakers on raids, and free-living conspecifics. Furthermore, hosts shifted their acceptance threshold over the seasons, presumably to reduce the costs of defence.

Structural and functional changes of the Dufour gland in gynes of the amazon ant Polyergus rufescens (Hymenoptera, Formicidae)

Colony foundation by the slave-making amazon ant Polyergus rufescens requires penetration of the young gyne soon after mating into a colony of the slave species. During this process, she uses decyl butyrate from her large Dufour gland as an effective appeasement allomone. The structural appearance and development of this gland shows a clear age-dependent evolution that is in line with its behavioural function. At the moment of eclosion, young females have a gland with an empty lumen but thick lining epithelium, of which the active secretory cells are characterised by a well-developed Golgi apparatus, abundant mitochondria and smooth endoplasmic reticulum. The basal plasmalemma shows deep invaginations that facilitate the uptake of precursors from the haemolymph, while intercellular contacts display conspicuous interdigitations in the apical cell part. During the first days of adult life, secretion starts to accumulate in the lumen. At the age of 3 weeks, the gland displays a large lumen filled with secretion and a thin epithelium that no longer displays secretory activity. By this time, the gynes are ready for penetration into a slave colony, being loaded with large quantities of the appeasement allomone that are necessary at this initial stage of the usurpation process.

Mating Behavior and Colony Founding of the Slave-Making Ant Formica sanguinea (Hymenoptera: Formicidae)

The mating and postmating behavior of reproductives belonging to two sympatric dulotic colonies of the facultative slave-making ant Formica sanguinea was analyzed in the field. Our observations showed that the European blood-red ant adopts a reproductive behavior similar to the “male aggregation syndrome.” Newly mated females return to a dulotic colony and often wait for a raid. Following a slave raid is an advantageous strategy to locate and invade host nests and to establish a new dulotic colony. In the laboratory, the following modes of colony founding were studied: independent, adoption, alliance, usurpation, and brood raiding. Independent foundation was possible only when several females were kept together. Alliance was obtained with females of two potential slave species (F. cunicularia, F. rufibarbis). Usurpation and adoption were more frequent in the incipient than in the mature host colonies. Mixed colonies were always obtained after the sack of the host pupae. It seems likely that, rather than conspecific adoption followed by budding, F. sanguinea relies on temporary parasitism to start new colonies.

Plasticity of the Cuticular Hydrocarbon Profile of the Slave-Making Ant Polyergus Rufescens Depending on the Social Environment

Analysis of cuticular hydrocarbon mixtures of the slave-making ant Polyergus rufescens and the Formica rufibarbis or F. cunicularia slaves with which it was living either naturally or after the slave species had been experimentally exchanged showed that cohabitation induced no qualitative homogenization of these species' cuticular signatures. The proportions of hydrocarbons common to both species tended however to be adjusted (in the case of the natural associations) or readjusted (in that of the experimental associations), especially in Polyergus towards those of their partners.On the other hand, differences were observed between the cuticular profiles of Polyergus and their Formica slaves which had been living separately from the original colony for several weeks in an experimental group, and those of the members of the original colony. The changes in the cuticular profiles occurred synchronously in all the individual members of the group.Comparisons between the cuticular versus postpharyngeal slave-maker and slave mixtures showed the existence of qualitative differences between the two mixtures. This indicates that the postpharyngeal glands are not directly involved in the production of the cuticular signatures. Some possible explanations for these results are discussed.

Haplometrotic colony founding by the slave‐making ant polyergus rufescens (hymenoptera, formicidae)

Several newly‐mated females of the European slave‐making ant Polyergus rufescens usually participate in slave raids and penetrate together the same target colony. This fact could result in a pleometrotic colony foundation. In the laboratory, two newly‐mated females of P. rufescens were introduced simultaneously into queenright artificial colonies of Formica cunicularia, the slave species present in the natal dulotic nest. The experiments were carried out using artificial colonies of two kinds: ‘simple’ (a nest connected with a foraging arena) and ‘complex’ (a simple colony connected with an empty nest serving as a flight‐chamber). In both cases, the two parasitic females never cooperated in attacking and killing the Formica queen. In fact, only one of the two was able to obtain adoption by the resident workers, the other being killed by them. Egg‐laying by the usurping queens was observed the following spring, and in the summer new mixed colonies developed: this is the ultimate criterion for looking upon colony foundation by the parasite as successful. In our experiments, pleometrosis did not occur and the dependent mode of colony foundation typical of P. rufescens led to a primary monogyny.

Selective acceptance of the brood of two formicine slave-making ants by host and non-host related species

In a laboratory choice-test, free-living ant workers ofFormica cunicularia andF. rufibarbis (subgenusServiformica), both potentially slave species of the obligatory slave-makerPolyergus rufescens, cared for cocoons of this parasite and for homocolonial cocoons at comparable rates. Both potential hosts did not differ in their capacity to rear the parasite brood. This fact is discussed in relation to host selection and specificity inP. rufescens. No such attraction and/or tolerance was found towards cocoons of the facultative slave-makerFormica sanguinea, which also enslaves both host species. Workers ofF. lugubris, a species which is never enslaved, destroyed cocoons from both slave-making species. The attractiveness of the brood ofP. rufescens for both potentially slave species could be due to an interspecific brood pheromone in addition to brood mimicry. An alternative hypothesis is a close phylogenetic distance between this slave-maker andServiformica species. The capacity to gain acceptance by adult slave workers might be one of the crucial evolutionary steps separating obligatory from facultative slave-making ants.

Selective adaptation of the cuticular hydrocarbon profiles of the slave-making ants Polyergus rufescens Latr. and their Formica rufibarbis Fab. and F. Cunicularia Latr. slaves

The results of comparisons between the cuticular hydrocarbon mixtures of the slave-making ants Polyergus rufescens, their Formica rufibarbis and F. cunicularia slaves and between slave and free-living workers (which were probably related to one another) from each Formica species showed the following. (1) Several products were common to all three species. (2) Each òf the two Formica species had its own particular products. (3) The Polyergus cuticular mixture did not contain any species-specific hydrocarbons but had some components in common with either rufibarbis or cunicularia. Because these products were present in Polyergus, whichever Formica species they enslaved, Polyergus must be able to synthesize their own cuticular hydrocarbons. (4) Cohabitation with another species as the result of slave making had no qualitative effects on the individual cuticular hydrocarbon mixtures: their composition was the same in the Polyergus whether living with F. rufibarbis or F. cunicularia and in the Formica of each species whether free living or enslaved. (5) The Polyergus resembled their Formica slaves, however, due to a tendency to adjust the proportions of some of the common hydrocarbons to those of their slaves; this tendency seems to have been reciprocal, although it was less marked in the case of the Formica. (6) The chemical signatures of mixed colonies inhabited by the same slave species depended mainly on the cuticular characteristics of the Formica slaves but also on those of the Polyergus, which differed from one colony to another. The finding that cuticular hydrocarbon mixtures of individuals of both species (slaves and slave makers) interacting within a mixed colony kept their species-specific hydrocarbons while the proportions of the common products showed a tendency to adapt to those of the other species suggests that there exists a selective mechanism probably involving the regulation of the synthesis of these products.

Interspecific aggression in colonies of the slave-making ant Harpagoxenus sublaevis

Colonies of the slave-making ant, Harpago- xenus sublaevis, may simultaneously contain workers of several Leptothorax slave species. We observed aggres- sive interactions among slave-makers, between slave- makers and slaves, and among slaves in 11 mixed colonies. The first two types of aggression appear to be correlated with reproductive competition for the pro- duction of males. Aggressive interactions among slaves, however, occurred mainly between slaves belonging to different species. In two colonies, in which one slave species clearly outnumbered the other, the majority at- tacked and finally expelled all nestmates belonging to the minority species. Our observations thus suggest that in Harpagoxenus colonies a homogeneous "colony odor" is not always achieved and that heterospecific slaves may occasionally be mistaken for alien ants. Gas chromatographic analyses of ants from mixed colonies similarly show that cuticular hydrocarbon profiles may differ strongly between heterospecific nestmate slaves.

Imprinting Effects on Host‐Selection Behaviour of Colony‐FoundingChalepoxenus muellerianus(Finzi) Females (Hymenoptera, Formicidae)

AbstractHost selection behaviour during colony foundation of newly inseminatedChalepoxenus muellerianusfemales belonging to three different imprinting types was investigated. Imprinting occurs both in larvae and in the young adults. It strongly influences the slavemakers' host choice. Young females get imprinted onto that slave species which is already present in the slavemaker colony. If nests of several potential host species are present in the habitat, the females will prefer the ‘familiar’ species for colony foundation. In addition to the imprinting influences, an innate preference ofC. muellerianusfor its main host speciesLeptothorax unifasciatuswas demonstrated. Host selection behaviour ofC. muellerianusfemales therefore depends on a blend of innate and learned characters. A genetically mediated preference of a certain host species can be reinforced by imprinting‐like phenomena. On the other hand, the same processes probably facilitate a change of the host species, for example in habitats, where the main host species is rare, and females are forced to switch over to other potential host species for colony foundation.

Colony takeover by a socially parasitic ant, Polyergus breviceps: the role of chemicals obtained during host-queen killing

Abstract. The behavioural adaptations of parasitic ant queens are more complex than those of parasitic birds, in which the egg-laying female approaches the nest only when the host parents are absent, and leaves immediately after egg deposition. Queens of the socially parasitic ant Polyergus breviceps are incapable of rearing their own brood, and therefore require the assistance of host Formica workers soon after egg laying. Accordingly, a newly mated Polyergus queen must penetrate a nest of Formica, kill the host queen, and become permanently accepted by the slave species' workers. Laboratory tests show that a Polyergus queen will similarly attack and bite a dead (and therefore motionless) Formica queen. Immediately after attacking the dead host queen, the Polyergus queen will be accepted by workers from any colony of Formica belonging to the same species of the dead queen (but will be attacked by workers from other Formica species). Preliminary results also indicate that any adoption-facilitating chemicals obtained by the Polyergus queen are still effective 1 week after killing the host Formica queen. When Polyergus queens raised in colonies containing F. gnava were introduced into nests of F. occulta, most showed little interest in attacking the resident Formica queen. In four of 10 tests, however, the Polyergus queen killed the foreign queen and was accepted by the F. occulta workers. Such chemical transfer of foreign-queen odours may have played a key role in the evolution of social parasitism in Polyergus.

Experience-independent attraction to host-species ant cocoons in the slave-makerFormica sanguineaLatr. (Hymenoptera Formicidae)

Newly eclosed workers of the facultative slave-making ant Formica sanguinea were either exposed to homocolonial cocoons, exposed to cocoons of the common slave Formica cunicularia, or reared without any cocoons. In all conditions, the F. sanguinea workers later cared for both the homo—and heterospecific cocoons. This indicates that the early social environment does not influence cocoon recognition and acceptance in this species, and probably the choice of the host. Moreover, a strong tendency to care for cocoons of the slave species is also shown by adult workers of this slave-maker coming from a pure colony.

Effects of nutrition on brood production and slavery in ants (Hymenoptera, Formicidae)

An artificial diet (Bhatkar andWhitcomb, 1970) was recommended for maintaining ant colonies. Comparative studies with a slave-making ant,Harpagoxenus sublaevis, and one of its slave species,Leptothorax acervorum, have shown that this diet is not sufficient for normal brood production in the independent speciesL. acervorum. In colonies of the slavemaker species fed with the diet, much more of the slave species pupae captured during raids are consumed than in colonies supplied with a more natural diet of insect tissue and honey. These experiments demonstrate that diet can seriously influence the results of breeding experiments, and we suggest that diet may be very important for certain behavioral studies as well. We conclude that the B.—W.—diet is probably inappropriate for many ant species which utilize both insect prey and honeydew.

Host Specificity in Raiding Behaviorof the Slave‐Making AntPolyergus Lucidus

In the pine barrens of Suffolk County, New York, at least three species of Formica (subgenus Neoformica) are used as slaves by the obligatory slave‐making ant Polyergus lucidus. In any single nest, however, only one slave species may be found. This contrasts with the sympatric, facultative slave‐making ants of the genus Formica (subgenus Raptiformica) in which single colonies often contain two or more species of slaves. The slave species exclusivity of P. lucidus might result in two ways: (1) raids could be made to only one slave species of the four available; or (2) raids could be made to more than one slave species, but the captured pupae could be consumed differentially by the resident slaves, favoring the survival to eclosion of only one slave species. This paper reports the results of a study demonstrating that colonies of P. lucidus will, if given a choice, raid only colonies of the slave species already present in the mixed nest. Since scouts typically lead nestmates to target Formica nests (Cool‐ Kwait & Topoff, 1984), this selective process must occur through the perceptions and actions of the scouts.

The Mating, Nesting and Ant Enemies of Polyergus lucidus Mayr (Hymenoptera: Formicidae)

Polyergus lucidus Mayr nested in sunny, well-drained fields. Its nest structure resembled that of Formica pallidefulva nitidiventris Emery, its slave species. Three types of external nest structure were observed: a simple crater of discarded pellets, a hidden entrance at the base of a grass clump and a chambered mound. Colonies occasionally became inactive and died out, probably because of an unknown disease. Adult sexual forms were present from early July until midSeptember; and mating flights occurred on hot, sunny afternoons between late July and mid-September. Alates normally flew without mating, but queens occasionally mated on the ground near the nest. Myrmica americana Weber preyed upon P. lucidus and its slaves as well as P. breviceps Emery. Acanthomyops claviger (Roger), Solenopsis molesta (Say), Monomorium minimum (Buckley), Lasius neoniger Emery and Formica fusca Linnaeus also harassed P. lucidus. Camponotus pennsylvanicus (De Geer) ambushed returning columns of P. breviceps.