Contents of Dufour glands in some formicine ants: queens and workers of Camponotus aethiops and a re-examination of Lasius fuliginosus

The Dufour gland secretions of both virgin queens and workers of Camponotus aethiops are similar and consist of straight chain hydrocarbons ranging from C₁₀–C₁₅ with C₁₁ the major compound. The difference between the two castes is that C₁₅ appears only as a trace in queens, and the total amount of secretion is smaller in queens than in workers.In Lasius fuliginosus, the Dufour gland secretion contains a series of straight chain hydrocarbons (C₁₀–C₁₇) with undecane the major compound, and a series of 2-alkanones ranging from C₁₃ to C₁₉.

---

Résumé Les sécrétions des glandes de Dufour sont toutes semblables et comprennent, chez les reines et les ouvrières de C. aethiops, une chaîne linéaire d'hydrocarbures de C₁₀ à C₁₅, avec C₁₁ comme constituant principal. Les différences entre les castes se traduisent chez la reine, par une teneur totale en sécrétions plus faible et l'existence de C₁₅ uniquement sous forme de traces.Chez L. fuliginosus, la sécrétion de la glande de Dufour comprend une série de chaînes linéaires d'hydrocarbures (C₁₀–C₁₇) avec l'undécane comme constituant principal, et une série de 2-alkanones allant de C₁₃ à C₁₉.

     

Differences in body sizes and physiological conditions among castes in the ponerine ant Cryptopone sauteri (Hymenoptera: Formicidae)

In several poneroid ant species, mated workers alone undertake reproduction. The reproductive systems of such species have been examined extensively. However, few studies have investigated species with alate queens, which reproduce after shedding their wings. We compared body sizes and the numbers of ovarioles between queens and workers in the ant Cryptopone sauteri with alate queens. We also compared ovariole development between the castes to evaluate their reproductive systems. Approximately 60% of the nests collected were queenless. We often detected unmated queens in the nests throughout the year, but did not obtain strong evidence for their reproduction. Although significant differences were observed in the number of ovarioles and body characteristics between the queens and workers, the differences were not as prominent as those observed in Formicinae and Myrmicinae. We propose two alternative hypotheses, failure of nuptial flight or postponement of reproduction, to explain the presence of unmated queens in the nests.     

Rapid temporal change in frequency of infanticide in a passerine bird associated with change in population density and body condition

Sexually selected infanticide, whereby unmated males obtaina mate by killing the dependent offspring of an already matedfemale, is a common alternative reproductive strategy in manyanimals. I estimated the frequency of infanticide in a populationof barn swallows, Hirundo rustica, during the period 1977–2002.Population size decreased by more than a factor 10 during thisperiod, and this decrease was associated with an increase inmortality, selecting for adults with better body condition.Density-dependent effects acted on infanticide through the relationshipbetween the relative number of unmated males and populationsize. Because males in prime condition are better able to defendtheir nests against infanticidal males, the frequency of infanticidedecreased as mean tail length and mean body condition of malesincreased during the study period. Therefore, a rapid decreasein population size, a decrease in the abundance of unmated males,and a concomitant increase in body condition have changed theimportance of infanticide from being a major cause of mortalityaccounting for more than 25% of all nestling mortality to beingalmost completely absent during a period of 25 years.     

Taxonomic studies on the ant genus Cerapachys Smith (Hymenoptera,Formicidae) from India

The Indianspeciesof the ant genus Cerapachys Smith are keyed. Twelve species are recognized of which 6 are described as new. The species are: Cerapachys aitkenii Forel, Cerapachys alii sp. n., Cerapachys anokha sp. n., Cerapachys besucheti Brown, Cerapachys biroi Forel, Cerapachys indicus Brown, Cerapachys longitarsus (Mayr), Cerapachys nayana sp. n., Cerapachys schoedli sp. n., Cerapachys seema sp. n., Cerapachys sulcinodis Emery and Cerapachys wighti sp. n. Geographic distribution and group affinities of the new species are discussed. A revised key to the Indian species is provided. The rare ergatoid queens of Cerapachys nayana, Cerapachys schoedli and Cerapachys seema are reported. Formed in response to selective pressures these ergatoid queens have a significant role in dispersal strategies and contribute much to our understanding of the biology of these ants.     

Polydomy in ants: what we know, what we think we know, and what remains to be done

The correct identification of colony boundaries is an essential prerequisite for empirical studies of ant behaviour and evolution. Ant colonies function at various organizational levels, and these boundaries may be difficult to assess. Moreover, new complexity can be generated through the presence of spatially discrete subgroups within a more or less genetically homogeneous colony, a situation called polydomy. A colony is polydomous only if individuals (workers and brood) of its constituent nests function as a social and cooperative unit and are regularly interchanged among nests. This condition was previously called polycalic, and the term polydomy was used in a broader sense for a group of daughter nests of the same mother colony (implying limited female dispersal), without regard to whether these different nests continued to exchange individuals. We think that this distinction between ‘polycaly’ and ‘polydomy’ concerns two disparate concepts. We thus prefer the narrower definition of polydomy, which groups individuals that interact socially. Does this new level of organization affect the way in which natural selection acts on social traits? Here, after examining the history of terms, we review all ant species that have been described as expressing polydomous structures. We show that there is no particular syndrome of traits predictably associated with polydomy. We detail the existing theoretical predictions and empirical results on the ecology of polydomy, and the impact of polydomy on social evolution and investment strategies, while carefully distinguishing monogynous from polygynous species. Finally, we propose a methodology for future studies and offer ideas about what remains to be done. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 90 , 319–348.     

The fate of radiolabelled C28 and C29 phytosterols in the honey bee

The fate of radiolabelled campesterol, sitosterol and 24-methylenecholesterol fed in chemically-defined diets to honey bee (Apis mellifera L.) workers was determined. At various intervals, sterols of prepupae, newly emerged adults and queens were analyzed qualitatively, quantitatively and radiochemically and it was determined that there was not sufficient radioactivity associated with cholesterol and/or desmosterol in any of the samples to verify that any of the three C₂₈ and C₂₉ sterols was dealkylated and converted to cholesterol. Similarly, there was no evidence for the conversion of campesterol or sitosterol to 24-methylenecholesterol. It was concluded that the major portion of the sterols incorporated into the tissues of the brood larvae originated from the worker bees used to establish the colony. There is good evidence supporting the premise that the workers can make available sterols from their endogenous pools to the nutrient in the hive and that they can replenish these sterols with those from the artificial diet. The queen is also able to replenish sterols utilized in egg production from those obtained by the workers from the artificial diet, and at the end of nine weeks queens contained more than four times as much sterol, on a ‘μg sterol per g fresh weight’ basis, than was found in fertile queens at the beginning of the test period.     

How to fool a virgin: Artificial dealation triggers oviposition in virgin Lasius niger queens

Once inseminated, ant queens rapidly shed their wings and start to lay eggs. Here we test whether there is a causal link between dealation and oviposition in the ant Lasius niger. We show that artificially dealated virgin queens start to lay eggs shortly after wing removal, whereas winged virgin queens hardly ever lay eggs. Dealate virgins do, however, produce fewer eggs than mated queens. These findings indicate that dealation does induce egg-laying, and that other factors, such as mating and/or insemination, further stimulate oviposition under natural conditions. Received 2 January 2006; revised 8 February 2006; accepted 4 April 2006.     

An experimental analysis of pleometrotic advantage in the desert seed-harvester antMessor pergandei (Hymenoptera; Formicidae)

Summary Starting colonies of the desert seed-harvester antMessor pergandei are clumped in the field and face severe intraspecific competition through brood raiding. Single foundress laboratory colonies ofM. pergandei are more likely to succeed at brood raiding with conspecific colonies if they are given additional workers and mature pupae several days prior to brood raiding. Per foundress fecundity remains constant across laboratory starting colonies established with 1, 3 and 5 foundresses. These results suggest that the selective advantage of cooperative colony foundation (pleometrosis) in this and similar species may derive directly from the ability of multiple foundresses to produce a larger brood raiding force.     

Queen brood reared in worker cells by the social wasp,Vespula germanica (F.) (Hymenoptera: Vespidae)

Summary The rearing of queen brood from worker cells in the nests ofVespula germanica (F.) in Australia was found at all stages of the colony cycle from early summer to autumn. Worker cells used to rear queens were 17% wider at their open ends than cells used for worker production, and in all other respects their dimensions were greater. The volume of a worker cell used for queen nearing was 21% larger than cells used for rearing workers but half the volume of a normal queen cell. Queen pupae reared in worker cells were significantly smaller than those reared in queen cells of the same nest. The spatial distribution of queen pupae in worker comb tended to be random although some evidence of nonrandom clustering was noted.The significance of this phenomenon is discussed in relation to caste differentiation and queen-control of gyne initiation and production. It is concluded that the phenomenon is neither seasonal nor due to some intrinsic component of the colony's annual cycle, and that it is unlikely to be an emergency queen-rearing response. Development of queens in worker cells may have occurred during favourable feeding regimes, perhaps determined by the benign Australian environment.