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The Hover Wasps
Abstract
The Hover Wasps (Stenogastrinae) comprise 58 described species in 7 genera which are distributed in the South East Asian tropics, from India to New Guinea. This chapter offers a sketch of their systematics. There follows a brief history of the studies by researchers of these wasps, focusing on the main problems, phylogeny and social evolution of these insects. General characteristic of other social wasps are briefly presented and discussed.
... The most complex forms of eusociality (labeled 'advanced eusociality', 'obligate complex eusociality', 'hypersociality', 'superorganismality') [1,5], characterized by strong queen-worker dimorphism and colonies made up of dozens to millions of individuals evolved in only these four lineages: approximately 150 million years ago in the termites [6], 150 mya in the ants [7], an estimated 87 mya in the corbiculate bees [8], and at least 80 mya in the vespid wasps [9]. Societies with less complex forms of eusociality (often labeled 'primitive eusociality', 'incipient eusociality' [2,10,11]) characterized by no or very little queen-worker dimorphism and colonies usually made up of a few to dozens of individuals also evolved independently in several other hymenopteran lineages, including 45 mya in xylocopine bees [2,12], at least twice independently 35 and 20 mya in halictid bees [13,14], as well as in stenogastrine and Microstigmus wasps [15]. ...
The evolution of large insect societies is a major evolutionary transition that occurred in the long-extinct ancestors of termites, ants, corbiculate bees, and vespid wasps. Researchers have long used 'social ladder thinking': assuming progressive stepwise phenotypic evolution and asserting that extant species with simple societies (e.g. some halictid bees) represent the ancestors of species with complex societies, and thus provide insight into general early steps of eusocial evolution. We discuss how this is inconsistent with data and modern evolutionary 'tree thinking'. Phylogenetic comparative methods with broad sampling provide the best means to make rigorous inferences about ancestral traits and evolutionary transitions that occurred within each lineage, and to determine whether consistent phenotypic and genomic changes occurred across independent lineages.
A checklist of the species in the subfamily Stenogastrinae is presented, including synonyms, nomenclatural changes, and distributional summaries. Forty-five species in seven genera are treated as valid, with an additional three subspecies. Excluding emendations, misspellings and nomina nuda, a further 16 names are treated as available synonyms, but eight of these names are listed only as questionable synonyms. A new combination is Parischnogaster aurifrons (Smith). Thirty new locality records are given.
The alignment of molecular sequence data published by Schmitz and Moritz (1998. Molecular phylogeny of Vespidae (Hymenoptera) and the evolution of sociality in wasps, Molecular Phylogenetics and Evolution 9: 183–191) supported closer phylogenetic relationship of Eumeninae to Polistinae + Vespinae than Stenogastrinae, from which they concluded that social behavior has independently evolved twice in the wasp family Vespidae. However, their analyses also showed the Vespidae as paraphyletic in terms of the bee family Apidae. Simultaneous analysis of these molecular data with published morphological and behavioral characters is presented. The resulting cladograms support monophyly of Vespidae, as well as monophyly of social wasps, with the primitively social Stenogastrinae being more closely related to the highly social Polistinae + Vespinae than the solitary Eumeninae. A realignment of the sequence data is also presented, which is more parsimonious than that published by Schmitz and Moritz. Analysis of the realigned sequences also supports monophyly of Vespidae, as well as monophyly of social wasps, with the Stenogastrinae being more closely related to Polistinae + Vespinae than are Eumeninae.
A taxonomic revision is given for the stenogastrine genus Eustenogaster van der Vecht, 1969, which is distributed from India to Southeast Asia and southern China. A total of 15 species, including three new species (E. fumipennis Saito, sp. nov., E. latebricola Saito, sp. nov. and E. spinicauda Saito, sp. nov.), are recognized in the genus. A key to species, descriptions of the new species, and notes on taxonomic status, morphological characters and distribution records of the previously described taxa are given.
The female and male of Liostenogaster vechti a new species of stenogastrine wasp, are described. This species is compared with the other three species of the genus Liostenogaster Van der Vecht 1969 [L. flavolineata (Cameron 1902), L. nitidipennis (Saussure 1853) and L. varipicta (Rohwer 1919)] from which it differs in various characters. The nests are implanted in large clusters on flat surfaces and take the form of a complete or incomplete ring or a bracket-like shape.
Members of the families Stenogastridae and Vespidae belong to the Vespiformis Group of the superfamily Vespoidea. There is no recent catalog or even a check-list of species of these families covering the Indian subregion. The only available reference is “The Fauna of British India” Vol. I, by C.T. Bingham (1897), where the family Vespidae also included the members of the family Stenogastridae (as recognized here) under the genus Ischnogaster Guérin (now known as Sternogaster Guérin. Bingham treated 7 genera comprising 47 species. Dalla Torre (1904) largely followed Bingham's classification and included 51 species in 7 genera from the Indian subregion. Aiyar (1916) in his catalogue of wasps and bees (Fossores, Diploptera and Anthophila) of the Indian Region since 1897, included 47 species in 4 genera and also followed Bingham's classification. Liu (1936–37), in his catalogue of the Vespidae of China recorded 21 valid species under 5 genera from India and the neighboring countries. In the present catalogue, which covers the Indian subregion, the family Vespidae is divided into two subfamilies, and includes 83 species under 9 genera, and the family Stenogastridae includes 6 species under 3 genera.
Summary The development of colony foundations of Belonogaster juncea juncea (Fab.) was studied both in the field (Messa quarter, Yaoundé, Cameroun) and in captivity (University of Florence, Italy). Colonies were first initiated by single females who could be joined by other foundresses (2 to 8) coming, in their great majority, from the same maternal colony as the initial foundress female. The co-foundresses remained faithful to one single colony or joined other colonies originating from the same maternal colony and remained, preferentially, on those with the more advanced immature brood. In most cases the nest starter turned out to be the dominant female and her position was usurped in only four cases. Only 25% of the haplometrotic foundations reached the postemergence phase while it was reached by 56.7% of the associative foundations. Only the latter succeeded in producing sexuals. The division of labour between associated females is similar to that observed in other social wasps with dominant individuals who are seldom absent from the nest, lay eggs and perform abdominal vibrations and subordinate individuals that are active foragers. The possibility of a swarming colony foundation in this species is briefly discussed.
Ropalidia opifex nests between leaves of trees, and builds cellophane-like nest walls of pure secretion. Nest structure, nest building behaviour, and the properties and chemical composition of the secretion are reported. The secretion mainly consists of protein. No chitin was found. The selective advantages of the leaf region niche for nesting, and of the unusual type of nest, are discussed.
A new species of hover wasp, Eustenogaster nigra Saito and Nguyen, is described based on females and males collected mainly in northern Viet Nam. The wasp is also distributed in mountainous areas of central Viet Nam and the southern part of China. All distribution records are from areas with more-or-less distinct seasons in terms of temperature. The nest is described and compared with those of other Eustenogaster species. A nest collected during early spring in Tam Dao National Park in northern Viet Nam, where there is a more-or-less distinct “winter”, had five males and six virgin females, suggesting that both sexes overwinter on their nest.
Chalogaster spatulata, new genus and species, is described from Viet Nam and northern Thailand. The genus belongs to the subfamily Stenogastrinae, a group of social wasps endemic to the Oriental Region. Cladistic analysis indicates that Chalogaster is the sister-group of the genus Metischnogaster van der Vecht. A revised key to the genera of Stenogastrinae is presented.
The phylogeny of the Stenogastrinae wasps is still under discussion and their systematic incomplete. In the present work we used geometric morphometrics, a technique based on a rigorous statistical assessment of shape, to compare the forewings of fifteen species of Stenogastrinae wasps belonging to four different genera to ascertain whether this approach may be used as a reliable method in the study of the taxonomy of the group. The results show that the wing vein junctions can be diagnostic for both genus and species identification. For the first time in this subfamily, we propose a phylogenetic classification of the species based on wing morphology that largely agrees with the cladistic data available at genus level and reflects the differences among species in terms of nesting material and architecture of their nest.
Abstract The active and coordinating capacity of defending the nest is a key feature of social insects. The present study investigates the presence of alarm pheromones in the venom of workers of the social wasp, Polistes dominulus. Laboratory experiments were performed with caged colonies of P. dominulus using a wind tunnel apparatus to test the behavioural response of workers to venom released by other workers and to venom extracts. Contrary to that previously reported for European paper wasps, the present results show that the venom is the source of alarm pheromones. Field experiments combining a visual (black target) and a chemical stimulus (venom extract) were performed to test the effect of the venom on the reaction of colonies. Wasps leave the nest, land on the visual target and attack the target significantly more once exposed to venom extract plus target than to solvent plus target. This work shows that the venom of P. dominulus workers elicits an alarm response, reduces the threshold for attack and acts as an attractant on targets. These results using P. dominulus indicate that, in both American and European species, colony defence is based on the same features, suggesting that chemical alarm is a widespread trait in the genus Polistes.
Phylogenetic relationships of the subfamilies and tribes of the Vespoidea (= Diploptera) are investigated using cladistic methods. A natural classification is proposed, sequencing seven tribes in six subfamilies within the single family Vespidae. Euparagia is the sister-group of the rest of the Vespidae. The Gayellinae and Masarinae are sister-groups, and are reduced in rank to tribes within the subfamily Masarinae. This is the sister-group of the Eumeninae + Stenogastrinae + Polistinae + Vespinae. The Zethinae is a paraphyletic group; both it and the Raphiglossinae are deleted and included in the Eumeninae. The Stenogastrinae is regarded as the sister-group of the Vespinae + Polistinae.
In this book, Itô presents data on tropical wasps which suggest that kin-selection has been overemphasized as an evolutionary explanation of sociality. He concentrates on the Vespidae (paper wasps and hornets), a group much discussed by evolutionary biologists because it exhibits all stages of social evolution:; subsociality, primitive eusociality, and advanced eusociality. The author reports field observations by himself and others in Central America, Asia, and Australia, showing that multiple egg-layers in a nest are not uncommon. Because coexistence of many `queens' leads to lower relatedness among colony members than in single-queen colonies, he suggests that kin-selection may not be the most powerful force determining observed social patterns. Instead, subsocial wasps may first have aggregated for defence purposes in habitats with a high risk of predation, with mutualistic associations among many queens. Through parental manipulation and then kin selection, differentiation into within-generation castes may have followed. Of interest to all students of ecology, evolution, and behaviour, this book beautifully illustrates the ability to combine wide-ranging data with thoughtful questions - the author's trademark.
The diversity of social behavior among birds and primates is surpassed only by members of the Hymenopteran insects, including bees, ants, and the genus Polistes, or paper-wasps. This volume combines incisive reviews and new, unpublished data in studies of paper-wasps, a large and varied group whose life patterns are often studied by biologists interested in social evolution. While this research is significant to the natural history of paper-wasps, it also applies to topics of general interest such as the evolution of cooperation, social parasitism, kin recognition, and the division of labor.
A taxonomic revision is given for the stenogastrine genus Eustenogaster van der Vecht, 1969, which is distributed from India to Southeast Asia and southern China. A total of 15 species, including three new species (E. fumipennis Saito, sp. nov., E. latebricola Saito, sp. nov. and E. spinicauda Saito, sp. nov.), are recognized in the genus. A key to species, descriptions of the new species, and notes on taxonomic status, morphological characters and distribution records of the previously described taxa are given.
In Belonogaster griseus (Fab.) (Hymenoptera Vespidae) from Somalia, pre-imaginal-presumably trophic-factors cause the appearance of two statistically distinct female castes. Queen-like (QL) 9 9 are not only larger on the average than worker-like (WL) 9 9 but also show slight differences in their shape (wider thorax). Such differences are correlated with their reproductive and behavioural destiny. The QL 9 9 are fertilized more often, reach greater fertility, are dominant, oophagous and mainly nest- founding. The WL 9 9 have opposing traits and forage more often. It seems very likely that some WL 9 9 never reach fertility and thus constitute a true sterile caste. Nests are usually founded by several QL 9 9 which set up a domination hierarchy. WL 9 9, which occasionally take part in nest-building, are more frequent during the initial life of the colony while the QL 9 9 prevail during the subsequent phases. The cfcf appear in large number towards the final phase. The causality of this incipient caste differentiation is discussed. The data now available on B. griseus modify the previous concepts of the position of the genus Belonogaster in the evolution of social wasps. No longer can it be considered as either an extremely primitive form of social organization or as a transitional stage between solitary and social forms of life.
CONCLUSIONS AND SUMMARY
1.
The morphology of nest development (stages) in Belonogaster griseus (Fab.) (Hymenoptera Vespidae Polybiini) serves as an introduction to a comparative study of the nests constructed by this genus.
2.
Bilateral symmetry of the comb is established at construction of first cell.
3.
The stages of predominantly longitudinal nest development, on an eccentric pedicel (laterinide nest), are characterized by the number of cells with eggs, larvae, mature larvae, and pupae and number of old, uninhabited, partially demolished cells.
4.
Morphological parameters (compared with other Vespidi) such as divergence of the alveolar axes (perhaps the highest among social wasps), the lack of displacement in the transverse sections and its limited use in longitudinal sections, explain the «hammock-shaped» form of the nest and its limit of development, reached when the more peripheral cells present a horizontal—or nearly horizontal—position.
5.
The construction techniques allowing the longitudinal development of the comb are: (i) the disposition of old cells, heavy pupae and mature larvae, young larvae and eggs in bands respectively ever more distant from the eccentric pedicel, (ii) the non re-use and partial demolition of the old cells, a normal phenomenon which—together with the lack of displacement—achieves a strong economy in the collection of nesting material, (iii) flection and rotation on a longitudinal plane of the partially demolished zone and (iv) crushing of the old cells by the distal shift of the load. Auxiliary, compensatory mechanisms—also measurable—are curvature of the alveolar walls and limited use of displacement in juvenile stages.
6.
Each of the three stages of development are characterized by various aspects (numerical increase in cells, sequence of cell addition, differences in cell depth, ribs, reinforcement beams, posterior chamber, etc.).
7.
The composition and resistance to stress of the construction material are discussed.
8.
The membrane covering the floor of the alveoli after extraction of the peritrophic sac is spun by the larvae.
A diagnosis is given for the vespoid genus Stenogaster Guérin, now considered to be restricted to New Guinea and some adjacent islands. Illustrated keys and descriptions are presented for 11 species, arranged in 2 groups: (1) fulgipennis species-group with fulgipennis Guérin (N.G.), unicolor (Smith) (Waigeu), adusta sp. n. (Misool and N.G.), decorata sp. n. (Misool and Japen), licina and concinna spp. n. (N.G.); (2) canaliculata species-group with canaliculata (Cameron) (N.G.), flavifrons sp. n. (Japen), glabra, pilosa and macilenta spp. n. (N.G.). The canaliculata species-group is distinguished by the considerably lengthened glossa and paraglossae, and segment 2 of the maxillary palpi and segment 1 of the labial palpi are also unusually long.
Social wasps of the subfamily Stenogastrinae represent an incipient stage of eusociality characterized by slight behavioural and morphological differences between egg-layers and non-egg-layers, and the preservation of several reproductive options in all adult females. Females may remain as helpers on the colony where they emerge, join a non-relative on another nest as egg-layer or helper, or begin a new nest. To explore eusociality in this group, a sample was collected from colonies of two of the best-studied species, Liostenogaster flavolineata and Parischnogaster alternata. Because females move between nests, and mother/daughter overlap in generations is slight, relatedness by pedigree is difficult to assess. Therefore, inbreeding and relatedness among colony members was estimated from allozyme variation. Inbreeding or population viscosity might elevate relatedness between colony members from the same cluster of colonies, but there was no evidence for this in either species. Among 57 female colony members from 22 colonies of P. alternata relatedness was 0·56 (se = 0·19) and among 95 female colony members from 38 colonies of L. flavolineata relatedness was 0·22 (se = 0·10), the lowest reported thus far for any primitively eusocial insect. Although a minority of females actually become egg-layers on their own colonies (a key factor in assessing the eusocial status of the group), females exhibit continual efforts to maximize their direct reproductive success in ways more reminiscent of vertebrate communal groups than of eusocial insects.
The Stenogastrinae, a group of subsocial wasps currently regarded as a subfamily of the Vespidae (Richards, 1962: 4), have a remarkable distribution. Most of the species are inhabitants of the Oriental region, where their range extends from Southern India eastward to the Philippine Islands, Celebes, Sumba and Flores. No Stenogastrinae have ever been collected in the Moluccas, but the group is well represented in the Papuan area, occurring throughout New Guinea and in the neighbouring islands of Waigeo, Misool and Aru. From 1831 to 1913 nine species have been described from this area, but from examination of the types we have learned that only six of these may be regarded as good species. Various collections made in New Guinea during the last forty years contain representatives of at least as many new species, and as the material of some of these is still very scanty, there is little doubt that further collecting will bring additional species to light. The known Papuan species belong to two distinct groups which are sufficiently different from their Oriental relatives as well as from each other to be treated as genera. One genus is Stenogaster Guérin, 1831, based on the first species of the subfamily to become known, S. fulgipennis Guérin; it was described from material collected at "Dory" (= Manokwari) in N. W. New Guinea by the famous expedition of the "Coquille". I hope to discuss the very difficult taxonomy of this genus in a future paper. The members of the second group, which forms the subject of this study, are placed here in a new genus, Anischnogaster. In general appearance the species of this genus are rather similar to certain species of the Oriental genus Parischnogaster Schulthess, but since particularly the males differ in several
In 1913 A. von Schulthess published under the title "Parapolybia Saussure" a revision of the Old World social wasps which in general appearance are similar to certain species of the American genus Polybia. Only a few months later R. du Buysson described some new species of "Polybia" from Asia and created a new genus Polybioides for one African and two Oriental species. Apart from the treatment of two African species of Polybioides in Bequaert's excellent work on the Vespidae of the Belgian Congo (1918; see also Bequaert, 1922) this group of wasps has since then received little attention. A detailed study of the Oriental wasps which at different times have been described or recorded as Polybia has led me to the conclusion that many of these belong to the genera Polistes and Ropalidia, and that the Old World genera Polybioides and Parapolybia are represented in the Oriental region by only four and three species, respectively. The confused taxonomy of these wasps is well illustrated by the fact that Von Schulthess's genus Parapolybia contains, in addition to four species now regarded as correctly placed under this name, two Polybioides, one Polistes and two Ropalidia. Du Buysson described the two sexes of a mimetic Polistes (imitator of Polybioides) as different species of Polybia (actually an exclusively American genus), and he used for the true Parapolybia the name Stelopolybia Ducke, another genus which is restricted to the New World. The relations between Parapolybia and Stelopolybia have remained obscure for a long time, and recently Richards & Richards (1951: 70) stated that no reliable character had been proposed to separate Parapolybia Saussure from Stelopolybia Ducke.
The female and male of Liostenogaster pardii, a new species of stenogastrine wasp, are described. This wasp is very similar to L. flavolineata (Cameron 1902) and also the initial stages of its nest (which is globular when mature) suggests that it is derived from a flavolineata nest type.
Summary In the Epiponini, queen number may vary from many to few during the colonial cycle. This cyclical oligogyny may be important for the maintenance of high genetic relatedness found in several taxa of epiponines. Even though queen reduction in accord with the colony cycle has either been demonstrated or inferred for many taxa, the factors responsible for queen number reduction remain largely unknown. In this study, behavioral interactions (queen-queen and queen-worker) were analyzed in Asteloeca ujhelyii. Conflicts among queens leading to queen elimination were more intense during colony establishment, and queens’ behavioral performances were significantly correlated with their potential reproductive capacity. Frequency of workers’ testing behaviors toward queens did not relate as a function of the colony cycle. Thus, it seems that in Asteloeca ujhelyii cyclical oligogyny is indeed behaviorally mediated.
Summary Alarm pheromones, chemical substances produced by social insects to alert the colony to threat, are the principal means by which colony defence is co-ordinated. We present the results of a study on alarm behaviour in 5 swarming species of wasps belonging to the genus Ropalidia. These species show a remarkably efficient strategy of alarm communication, including visual display and attack synchronization. We show that pheromones released from the venom gland play an important role in alarm recruitment in species belonging to the Ropalidia flavopicta group, but not in Ropalidia sumatrae. We analysed the contents of the venom reservoirs content of four of the studied species by gas chromatography-mass spectrometry. Glands were found to contain a complex mixture of volatile compounds as well as spiroacetals of higher molecular weight. Interestingly, despite all species producing similar chemical compounds from the venom gland, these were found to elicit alarm behaviour in only those species that build nest envelopes, suggesting a link between chemical release of alarm behaviour and the evolution of nest architecture in Ropalidia wasps.
The females and males of Liostenogaster topographica, L. tutua, L. filicis, L. abstrusa and L. campanulae, new species of stenogastrine wasps from peninsular Malaysia, are described together with their nests.
Social behavior occurs in some of the smallest animals as well as some the largest, and the transition from solitary life to sociality is an unsolved evolutionary mystery. The Evolution of Social Wasps examines social behavior in a single lineage of insects, wasps of the family Vespidae. It presents empirical knowledge of social wasps from two approaches: one that focuses on phylogeny and life history; and one that focuses on individual ontogeny, colony development, and population dynamics. It also provides an extensive summary of the existing literature while demonstrating how it can be clouded by theory. This approach to the conflicting literature on sociality highlights how often repeated models can become fixed in the thinking of the scientific community. Instead, it presents a mechanistic scenario for the evolution of sociality in wasps that changes our perspective on kin selection, the paradigm that has dominated thinking about social evolution since the 1970s.
A revision of the nocturnal social wasp genus, Apoica, is presented. The revision is based on a cladistic analysis of morphological, behavioral, and molecular characters of the nine nominal species. The subgenera Deuterapoica and Apoica are consistent with the phylogenetic results, and are thus retained. A new species, Apoica ellenae, whose phylogenetic position is uncertain, is described. A variant of A. albimacula from Peru is noted. This brings the total number of species in the genus to 10.
The Stenogastrinae wasps have been proposed as a key group for an understanding of social evolution in insects, but the phylogeny of the group is still under discussion. The use of chemical characters, in particular cuticular hydrocarbons, for insect taxonomy is relatively recent and only a few studies have been conducted on the cuticular polar substances. In this work, we ascertain, by the matrix-assisted laser desorption ionization-time of flight mass spectrometry technique, that different species of primitively eusocial hover wasps have different compositions of the epicuticular polar compounds ranging from 900 to 3600 Da. General linear model analysis and discriminant analysis showed that the average spectral profiles of this fraction can be diagnostic for identification of the species. Moreover, for the first time we show population diversification in the medium MW polar cuticular mixtures in insects. In conclusion, the results demonstrate that the chemical characters are consistent with the physical characters and the study support the importance of medium MW polar substances as powerful tools for systematics (chemosystematics) and chemical ecology (fertility signal and population characterization) in a primitively social insect taxon.
In New Guinea, nests of the wasp, Anischnogaster iridipennis are built of mud, with 1 to 18 flask-like cells attached to rootlets, under overhanging banks in the tropical rainforests, usually attended by a single female and frequently parasitised by tachinids.
In an Australian swarm-founding polistine, Ropalidia romandi, exposure of squashed venom sacs of workers outside the nest reduced the threshold for attack. This treatment induced recruitment of several workers to the outer surface of the envelope, while a physical stimulus given to the nest caused a sudden emergence of a large number of workers from the nest. Visual cues induced attack; black objects were preferentially attacked by the wasps while white ones were rarely attacked.