Queen Castes Research Articles

Dominance hierarchy and reproductive conflicts among subordinates in a monogynous queenless ant

In insect societies lacking morphologically specialized breeders and helpers, reproduction is often restricted to behaviorally dominant individuals. Such societies occur in about 100 species of ants that have secondarily lost the queen caste. All females, who are morphologically workers, can potentially mate and lay eggs but only a few do so, and we demonstrate in Dinoponera quadriceps that this is regulated by a dominance hierarchy. Six types of agonistic interactions allowed the ranking of 5–10 workers in the hierarchy (n 5 15 colonies). In particular, alpha and beta had characteristic behavioral profiles and were easily recognized. Only alpha mated, and workers ranking beta to delta sometimes produced unfertilized, male-destined eggs. Natural replacements (n 5 19) and experimental removals (n 5 15) of alpha demonstrated that beta was the individual most likely to replace alpha, although gamma and more rarely delta sometimes did, and we discuss the conflict that occurs among high-ranking individuals over who should replace alpha. After such replacements, the new alpha behaved more aggressively than the overthrown alpha. Newly emerged workers tended to reach high ranks and displaced older high-ranking individuals down the hierarchy. Lowranking subordinates often prevented high-ranking individuals from replacing alpha by biting and holding their appendages (worker policing), which is consistent with the pattern of relatedness associated with monogyny and monandry in D. quadriceps. We investigated the relative importance of chemical communication and dominance interactions to regulate reproduction. Alpha, beta, and sterile workers have different signatures of cuticular hydrocarbons, and these may provide honest information which underpins worker policing by low-ranking individuals.

Monogyny and regulation of worker mating in the queenless antDinoponera quadriceps

The morphologically specialized queen caste has been lost in various ponerine ants, and mated workers (‘gamergates’) reproduce instead of queens. Unlike previous reports in the literature, we found only one gamergate in each colony ofDinoponera quadriceps. We documented monogyny by dissecting ovaries and spermathecae in 914 workers from 15 colonies, and by observing mating in the laboratory. In colonies without a gamergate, aggressive interactions among some of the unmated nestmates led to the behavioural differentiation of a top-ranking worker (‘alpha’), which laid almost all the eggs. Only the alpha went outside the nest at night, and mated if foreign males were present (N=11 tests), thus becoming a gamergate. The alpha was sexually attractive even when her ovaries were not yet active. After intromission, the male remained linked to the alpha while she severed the end of his abdomen. Pieces of the male genitalia remained attached to her genital tract, and she removed them after 30±18min (X±sdN=9). We interpret this to be a mating plug, preventing other males from fathering her offspring. None of these newly inseminated gamergates continued to go outside the nest, and, when tested, they never re-mated (N=4). Thus, gamergates ofD.quadricepsprobably mate only once. In queenless ant species, comparative evidence indicates that worker mating is often regulated in monogynous species, while unrestricted mating of young individuals is typical of polygynous species (oviposition is regulated subsequently). Furthermore, the occurrence of either monogyny or polygyny influences the mating strategies of males, and mating plugs have been reported only in some monogynous species.

Morphological caste differences in the neotropical swarm‐founding and polygynous polistine wasp, Polybia Scutellaris

In the swarm founding wasp, Polybia scutellaris, the worker and the queen caste are morphologically distinct. Only queens have activated ovaries and are inseminated. Queens are larger in 9 morphometric characters analysed. Caste differences in polistine wasps and in particular in the polygynous colonies of the neotropical Epiponini are discussed.

Redescription of the Ant Leptothorax (S. STR.) Scamni Ruzsky, 1905

Worker and queen caste of the ant Leptothorax (sensu stricto) scamni Ruzsky, 1905 are formally described and a neotype is designated. The species is distinguished from other Leptothorax (s. str.) by extraordinarily long, finger‐shaped propodeal spines. L. scamni appears to be a rather rare, patchily distributed ant in alpine coniferous forests in the Caucasus (Russia and Armenia) and northern Turkey.

The social biology ofHagensia havilandi(Forel 1901)(Hymenoptera Formicidae), and the origin of queenlessness in ponerine ants

Hagensia Havilandi (Forel 1901) is a forest-dwelling ant related to species in the genera Pachycondyla Smith 1858 and Diacamma Mayr 1862. Mated workers fill The reproductive function of the queen caste, which has been lost. There is only one mated worker in each colony, but 8–42 virgin workers. Facultative, complete sterility in virgin workers appears to be brought about by physical interaction with the mated worker. Division of labour in colonies Of H. Havilandi is similar to that of other queenless ponerine ants. Reproductive regulation in this species and its near relatives is reviewed. Reproductive and behavioural traits of queenless members of the ponerini are examined for their general value as indicators of phylogenetic relationship. It is concluded that before any insight into the evolutionary loss of the queen caste can be gleaned from comparative studies of ponerine ants, thorough phylogenetic studies are needed.

Evolutionary trends in the reproductive biology of ponerine ants (Hymenoptera: Formicidae)

The colony sizes and ovariole numbers of eight ponerine, one cerapachyine and one doryline species are reported. The ergatoid queens of five of these species are described briefly. Workers of the Hypoponera, Leptogenys and Anochetus species entirely lack ovaries, the first report of obligate sterility in this subfamily. Three evolutionary trends in the reproductive biology of the Poneriae are discussed: an increase in ovariole numbers and specialization for reproduction in the queen caste; worker sterility and increasing reproductive differentiation between the castes; and the evolutionary loss of specialization for dispersal in ergatoid queens.

A syndrome leading to ergatoid queens in ponerine ants (Hymenoptera: Formicidae)

The hypothesis that ergatoid reproductives of ponerine ants are derived from the worker caste is rejected on morphological and theoretical grounds. A syndrome by which ergatoid morphology could arise in the queen caste of some species is then outlined, implicating a combination of dietary specialization on prey that cannot be handled by a single ant, and an inability of foundresses to initiate new colonies alone. Secondary aspects of ergatoidy which may facilitate its development, and the occurrence of ergatoidy in other ponerine species, are explored. It is suggested that this syndrome gave rise to legionary behaviour in the army ants of the Dorylinae and Ecitoninae.

Nestmate discrimination in a ponerine ant (Rhytidoponera sp. 12) without a queen caste and with a low intra-nest relatedness

Various ponerine ants do not have a queen caste, and it is not known whether this modification in the eusocial structure affects the ability to recognize between nestmates and non-nestmates. Foragers ofRhytidoponera sp. 12 were collected from 15 adjacent nests, and were immediately tested in pairwise introductions between nests. Out of 179 tests, 84 % resulted in fighting, and in another 5 % there were unambiguous signs of hostility. Furthermore, natural aggression between marked foreign workers was observed near the nests. There are many mated laying workers in the colonies ofR. sp. 12, and this leads to nestmates being less genetically-similar (whereupon their genotypically-correlated recognition odours may vary considerably). Since there is no influence of a queen odour, the existence of a distinct colony identity reveals that workers are able to learn the spectrum of individual odours of their nestmates. In instances where workers from two foreign nests did not fight, each of them was again tested with other foreign ants (from the same or a different nest). They could discriminate in some cases but not others. This suggests that a gestalt odour does not exist in these colonies, but larger samples are needed to confirm this. Colonies ofR. sp. 12 are not polydomous, as had been previously suggested. The transfer of workers which sometimes occurs between nests represents episodes of nest emigration.

Worker reproduction in the ponerine ant Ophthalmopone berthoudi: an alternative form of eusocial organization

Colonies of the ponerine Ophthalmopone berthoudi were collected throughout the year. The queen caste is absent. Dissection of large numbers of workers revealed that many of them (up to 100 in one nest) are inseminated and produce eggs. The ovaries are small and contain very few mature oocytes, indicating that there is a slow rate of egg-laying. Workers are produced throughout the year, and all are capable of becoming functional reproductives. However, only those that are sexually-attractive during the limited period of male activity become mated. Thus the percentages of mated laying workers (=gamergates) fluctuate seasonally (Fig. 2). Successive generations of gamergates do not overlap. Observation of nests in the field and in the laboratory indicated that gamergates were never active above ground. There is no aggression between them, and their numbers are not socially regulated. There are few interactions between gamergates and non-reproductive workers, and the former do not acquire more food during termite meals. The notion of parental oppression is undermined by the complete loss of the meen caste, while the nature of the breeding system of this ant leads to the prediction of low relatedness between nestmates.

Notes on the biology of Pheidole lamia (Hymenoptera: Formicidae) at its type locality (Austin, Texas).

Notes on the biology of Pheidole lamia (Hymenoptera: Formicidae) at its type locality (Austin, Texas).

Developmental kinetics of juvenile hormone inactivation in queen and worker castes of the honey bee, Apis mellifera

The kinetics of in vitro juvenile hormone-I inactivation during development, beginning from 2.5 days old larvae to the pupal stage (Pw), was followed in worker and queen castes of the honey bee, Apis mellifera. Juvenile hormone degrading enzymes are present in the larval homogenates of both the castes. The profile of JH-degradation shows high and specific enzyme activity peaks in the initial period of development, i.e. from 2.5 to 3.5 days. Between 4 to 5 days the level of JH-degrading enzymes is very low and reaches thereafter another peak of activity during the stage of pharate pupa. In comparison with worker larvae, queen larvae possess significantly higher specific as well as absolute enzyme activities. Ester hydrolysis mediated by JH-specific esterases is the major pathway of JH-deactivation. Larval homogenate when fortified with NADPH 2 did not show any significant increase in the amount of JH-degradation. In presence of Triton X-100 (0.5%), JH-esterase activity is inhibited to the extent of 85%. JH-esterase activity is principally located in the cytosol while microsomal and mitochondrial fractions were found to be inactive in this respect.

Vergleichende Analyse des Kohlenhydratstoffwechsels bei den Kasten der Honigbiene, Apis mellifera

Enzymatic activities of ALD ∗ ∗ For abbreviations see page 1252. , GAPDH, GDH, G-6-PDH, HK, LDH, PGK, PGluM, Ph a+b, and TIM have been determined in the 100,000 g supernatant of a total extract from both castes of the female honey bee. Data are given for the larval, pharate pupal, emerged pupal, and adult stages. The amount of glycogen, glucose, fructose, glucose-6-phosphate, fructose-6-phosphate, lactate, pyruvate, α-glycerophosphate, and of total lipid has been measured. These studies have been accomplished as a contribution to the understanding of the metabolic action of the determining substance contained in royal jelly, which is responsible for queen bee formation. In both castes aldolase activity is increased about twentyfold in the pharate pupa compared with the values of the larval stages. The activity then continuously drops to the newly emerged adult, which contains about 20 per cent of the maximum activity. A similar course is found in the case of phosphorylase. The activities of all the other enzymes follow a more or less U-shaped curve with high levels in the larvae and newly emerged adults. In the pupae the following minimum values of specific activity are reached (per cent of maximal activity): ALD 20, GAPDH 40, GDH 30, G-6-PDH 20, HK 30, LDH 30, PGK 30, PGluM 15, TIM 35. As a difference between both castes, an abrupt drop of several enzyme activities is seen in the worker bee between the larval and pharate pupal stage towards a level lower than that of the queen pupa (TIM, HK, GDH, LDH). The proportion of GDH LDH points to a more aerobic carbohydrate metabolism in the queen than in the worker. The accelerated development of the queen corresponds to a high activity of PGluM, HK, and TIM. The enzyme patterns in queens and workers follow the same endogenic rhythm dependent on the stage and not on the duration of adult development. The influence of the determining substance is more pronounced at the substrate level. After the sensible phase of determination glycogen concentration drops in the 4-day-old queen larva to a low level of about 5 mg/g fresh wt., which is rather constant in the further stages. The worker builds up a high amount of glycogen with a maximum of about 50 mg/g in the white-eyed pupa. This storage decreases continuously and attains the same low level in the newly emerged adult as the queen caste. Similar results are shown by the determination of total lipids, with values of about 10 mg/g in the queen pupa and about 40 mg/g in the worker. In both castes α-glycerophosphate, pyruvate, and lactate are enriched during larval development. In the following pupal stage all metabolite levels are lowered. The concentration of α-glycerophosphate during larval and pupal development is about 50 per cent higher in the queen than in the worker. During diapause lactate concentration is about twofold higher in the queen.

Nesting behavior ofHalictus scabiosæ in Switzerland (Hymenoptera, Halictidæ)

The structure and populations of seven nests ofHalictus scabiosae were studied in Geneva during July and August, 1964. Cells, containing brood of various ages, were radially arranged along the branching burrows. The one to six females in each nest did not belong to distinct worker and queen castes. This is in contrast to reports of distinct castes in what appears to be the same species from France. Most pollen collectors in the Geneva population were inseminated and some probably laid eggs.

THE WORKER CASTE OF HARPAGOXENUS CANADENSIS SMITH (FORMICIDAE).

During the summers of 1941 and 1942, with the help of students, I collected in the vicinity of Duluth, Minnesota, some individuals of a species of ant recently described by Dr. M. R. Smith (1939), from Quebec, Canada. The original account of Harpagoxenus canadensis was based on the queen caste, an intermediate ergatoid female type, and a simple ergatoid female type, representing 12 specimens in all.

Bactericidal Properties of Royal Jelly of the Honeybee*

The natural diet provided the queen caste of the honeybee has bactericidal properties. The food is commonly called royal jelly and is secreted by the pharyngeal glands located in the upper and anterior parts of the head cavity. The material is secreted by members of the worker caste and is placed in the cells containing the bee larvae.