Morphology of the fifth sternal glands of Neotropical social wasps (Hymenoptera,Vespidae, Polistinae)

Glands play a central role in the social behavior of insects, and comparative analysis of their structure may provide insights about their evolution and their role in insect social biology. Here, we describe the glands of the fifth metasomal sternite of ten polistine wasps with different social behaviors. The glands of foragers of these species were studied using semithin sections of Araldite‐embedded tissue, and scanning electron microscopy. The structure of the glands observed was mostly similar to what has previously been reported for independent‐founder and swarm‐founder species, respectively. Scale‐shaped modifications in the fifth sternite are reported for the first time for members of the genera Synoeca and Epipona. Two previously unreported glands in the fifth sternite are also described. A more restrictive definition of the name Richards' gland is proposed, applying to the class 3 cells associated with scale modifications of the fifth sternite, based on structural differences between the glands observed, homology requirements, and functional evidence. Previous phylogenetic reconstructions of this character suggest that it appeared early in the Vespidae and disappeared four times, with a single reappearance in the genus Vespula. The restricted definition of Richards' gland suggests that this structure is an exclusive trait of the Epiponini, with two reversals.     

Richards' gland and associated cuticular modifications in social wasps of the genusPolybia Lepeletier (Hymenoptera,Vespidae, Polistinae,Polybiini)

Insectes Sociaux - O.W. Richards recently discovered an exocrine gland that opens on the fifth (penultimate) sternite of females of many species of polybiine wasps. Recent experimental evidence...     

Morphology and ultrastructure of a secretory region enclosed by the venom reservoir in social wasps (Insecta,Hymenoptera)

The morphology and ultrastructure of the convoluted gland inside the venom reservoir of four species of social Vespidae are described. The cells of the venom gland (including the convoluted gland) can be divided into six groups: (1) epithelial cells, (2) glandular cells with the end apparatus secreting into the tubule inside the convoluted gland (internal or embedded tubule), (3) a continuous arrangement of glandular cells with the end apparatus secreting directly into the venom reservoir, (4) glandular cells that are loosely dispersed along the tubule lumen between the free tubules and the embedded tubule of the convoluted gland, (5) secretory cells of the free tubules and (6) duct cells. One kind of secretory cell, hitherto unknown and described in this paper (group 3), is characterized by the presence of a well-developed end apparatus, usually with enlarged extracellular spaces, but lacking the normally associated duct cells. The secretory cells contain several stacks of granular endoplasmic reticulum, but these are mainly concentrated in the middle of the cell. The basal half of the cells contains many lipid droplets. Although the function of the convoluted gland is not yet understood, an hypothesis is related to what is known of the function of reservoir secretory cells in solitary wasps. All wasp species studied showed the same organization of the convoluted gland, which clearly distinguishes their venom gland from that of Sphecidae.     

Distribution of social wasps (Hymenoptera: Vespidae) in New Zealand in 1987

Abstract

More than 50 000 social wasps (Hymenoptera: Vespidae) were collected between March and August 1987 from throughout New Zealand. The most widespread species is the German wasp (Vespula germanica). The common wasp (V. vulgaris) has colonised about half the country and appears to be still spreading. It tends to appear in urban areas first, presumably because it is transported there with people and/or their belongings. The Asian paper wasp (Polistes chinensis) and Australian paper wasp (P. humilis), are confined to the northern half of the North Island, but the former species is spreading south.     

Keys to the genera of social wasps of South-East Asia (Hymenoptera: Vespidae)

Illustrated identification keys are provided for higher taxa and all genera of social wasps found in South‐East Asia.     

Comparison of three liquid lures for trapping social wasps (Hymenoptera: Vespidae)

Two citrus-based sodas and a known wasp attractant were compared in a field trial to assess their attractiveness to local nuisance wasp species. The wasps captured included Vespula germanica (F.), Vespula maculifrons (Buysson), Vespula vulgaris (L.), Vespula flavopilosa Jacobson, Vespula squamosa (Drury), Dolichovespula maculata (L.), Polistes fuscatus (L.), Polistes metricus Say, and Polistes dominulus (Christ). Wasps in the genus Vespula were present in significantly higher numbers in traps than Dolichovespula and Polistes. Both citrus soda products were superior to the isobutanol-acetic acid mixture as attractants for almost all of the wasp species.     

Relationship between body size and flying-related structures in Neotropical social wasps (Polistinae,Vespidae, Hymenoptera)

Body size influences wing shape and associated muscles in flying animals which is a conspicuous phenomenon in insects, given their wide range in body size. Despite the significance of this, to date, no detailed study has been conducted across a group of species with similar biology allowing a look at specific relationship between body size and flying structures. Neotropical social vespids are a model group to study this problem as they are strong predators that rely heavily on flight while exhibiting a wide range in body size. In this paper we describe the variation in both wing shape, as wing planform, and mesosoma muscle size along the body size gradient of the Neotropical social wasps and discuss the potential factors affecting these changes. Analyses of 56 species were conducted using geometric morphometrics for the wings and lineal morphometrics for the body; independent contrast method regressions were used to correct for the phylogenetic effect. Smaller vespid species exhibit rounded wings, veins that are more concentrated in the proximal region, larger stigmata and the mesosoma is proportionally larger than in larger species. Meanwhile, larger species have more elongated wings, more distally extended venation, smaller stigmata and a proportionally smaller mesosoma. The differences in wing shape and other traits could be related to differences in flight demands caused by smaller and larger body sizes. Species around the extremes of body size distribution may invest more in flight muscle mass than species of intermediate sizes.     

The queen colony phase of vespine wasps (Hymenoptera, Vespidae)

Characteristics of queen nests of the Vespinae are reviewed including the number of cells and each brood stage in the mature nest, cell-building and egg-laying rates, length of each brood stage and the occurrence of brood cannibalism. Success rates of queen nests of the Vespinae are reviewed with their causes of failure including the effect of queen usurpation, and with particular reference to variation of queen behaviour or queen quality. Evidence for the differences between potentially successful and unsuccessful queen nests is given. Simulation models of queen nests are developed for potential successful and unsuccessful colonies to determine the extent of larval cannibalism, larval life extension and for unsuccessful queen nests, oophagy. The variation of cell building rate, the importance of ambient temperature and the fast development of the first batch of eggs are considered in relation to polistine studies. The causes of the variation of queen quality are unknown but could be related to the amount of food received as larvae or as adults before leaving the natal colony.     

Some aspects of interrelations between ants (Hymenoptera,Formicidae) and polistine wasps (Hymenoptera,Vespidae)

Embodied, situated and enactive aspects of relationships of polistine wasps with ants are considered within the framework of the theory of autopoiesis. The idea of the embodied interaction implies specific nestbuilding and protective behavior in polistine wasps. The paper examines the adaptive role of applying ant repellent on the petiole and nest and the latitude gradient of such behavior in re-social wasp species. The situated interaction is considered in the environmental context: the mortality of Polistes gallicus (L.) colonies as a result of predatory attacks of ants Myrmica bergi Ruzsky is analyzed in the Lower Dnieper basin (Ukraine). The enactive interaction includes both spontaneous autonomous activity of its participants as a result of self-organization and specific features of the spatial structure of the prey’s population forming under the impact of the predator. The applicability of some “predator-prey” models is discussed.     

Self-organization of populations of polistine wasps (Hymenoptera,Vespidae, Polistinae)

In a natural population of Polistes dominulus (Christ) in the Black Sea Biosphere Reserve, Ukraine, the fluctuations of the number of nests founded were monitored in 1992–2008; the variations in the spatial and ethological structure of populations as well as in the colony organization patterns were examined. The highest indices of foundress fecundity (daily egg production, the foundress longevity after emergence of worker), colony productivity (the number of adults reared, the intensity of repeated cell use) and the efficiency of colony functioning (the degree of worker specialization and the mode of loyal or aggressive relationships between individuals) were characteristic of the population growth phase. In contrast, low indices were recorded during the peak and the decline phases. Transition to a more complicated social organization is favored by the self-organization process that accelerates the appearance of such interrelated features as a complex communication system, worker specialization, and their ability to perform complicated tasks. The study is focused on spatio-temporal processes in the population, using the body melanin patterns as markers of the social roles of foundresses. The changes observed in the population phenotypic structure are considered from the viewpoint of autowave processes. Analysis of the functional and numerical response of paper wasp parasitoids to changes in the host population density has shown that the regulating effect becomes noticeable only under such a concurrence of the life cycles of the parasitoid and the host when the larvae of the first cohort of workers become infested. The application of the concept of self-organized criticality used to describe complex systems with developed fluctuations results in a better understanding of population regulation in resocial insects.     

Trapping social wasps (Hymenoptera: Vespidae) with acetic acid and saturated short chain alcohols

Nineteen compounds were evaluated in combination with a solution of acetic acid as baits for trapping the German yellowjacket, Vespula germanica (F.), the western yellowjacket Vespula pensylvanica (Sausssure), and the golden paper wasp Polistes aurifer Saussure. Compounds with three to six carbon chains or branched chains and with a hydroxy functional group were selected for testing based on their similarity to isobutanol. They were compared with isobutanol with acetic acid, which is a known wasp attractant. None of the compounds tested were superior to isobutanol when presented with acetic acid as a lure for these species of wasps. However, traps baited with either the S-(-)- or the racemic mixture of 2-methyl-1-butanol in combination with acetic acid captured similar numbers of both species of yellowjackets, compared with isobutanol with acetic acid. Polistes aurifer responded strongly to the S-(-)-enantiomer and to the racemic mixture of 2-methyl-1-butanol with acetic acid and not to the R-(+)-enantiomer with acetic acid.     

Pulp partitioning and worker specialization in polistine wasps (Hymenoptera,Vespidae, Polistinae)

The character of pulp partitioning was studied in three Palaearctic polistine wasps (Polistes dominula and P. gallicus in the Black Sea Biosphere Reserve, and Polistes nimpha in the Lugansk Nature Reserve, Ukraine) and in five Neotropical species (P. lanio, P. versicolor, Mischocyttarus injucundus, M. alfkeni, Metapolybia cingulata, and Protopolybia exigua in Trinidad). In independent-founding Polistes and Mischocyttarus species, all cases of pulp partitioning were connected with aggression on the part of the foundresses. An experimental increase of nesting density of P. dominula led to changes in the relative abundance of workers in the polyethic task groups. Some workers practically stopped hunting and switched over to pulp delivery; some of these workers possessed well-developed ovaries and were able to lay eggs. The experimentally removed part of the nest envelope in the swarm-founding wasp Metapolybia cingulata was restored only in colonies that included young workers. The specific features of nest building activity in independent-founding and swarm-founding polistine wasps are discussed.     

Possible pathogens of social wasps (Hymenoptera: Vespidae) and their potential as biological control agents

Abstract

Boutin et al. (2006) claimed that American and Eurasian red squirrels use an unknown environmental cue to anticipate the availability of the abundant food of an autumn seed mast, and produce more young than usual in the previous spring and summer. But these small mammals need increased supplies of protein to produce and support young, therefore they must have had access to some other protein‐rich food that was available before the mast was ripe. There are other small mammalian seed‐eaters that increase their reproductive output ahead of the maturation of a seed mast. It seems likely that, in each case, females are able to produce extra young in advance because they eat the amino acid‐rich inflorescences and unripe seeds of the mast and/or larval insects that also increase their numbers in the spring of a mast year by eating the same enriched plant food.     

Polymorphic microsatellite loci for eusocial wasps (Hymenoptera: Vespidae)

Hymenopterans are an important model for studying the evolution of cooperation in animal societies. Here, we characterize 19 microsatellite loci, isolated from the common wasp Vespula vulgaris, that can be used to study genetic variation in three genera (seven species) within the Vespidae. The number of alleles in V. vulgaris was moderate, varying from 2 to 14, with expected heterozygosity ranging between 0.04 and 0.93. Eleven loci amplified DNA in V. austriaca and Dolichovespula sylvestris, nine in V. germanica, eight in Vespa crabro and V. rufa, seven in D. media and only five loci could be used for D. norwegica.