Nesting biology of four species of Trypoxylon (Trypargilum) (Hymenoptera: Crabronidae) in Chaco Serrano woodland, Central Argentina

Trypoxylon (Trypargilum) (Crabronidae) wasps are solitary spider predators that can build their nests in artificial trap-nests, which enables study of their nesting architecture and biology. Twenty traps (each containing 15-30 internodes of cane) were placed in each of nine sites of Chaco Serrano Woodland in Central Argentina (Córdoba) in October 2005, and were recovered in June 2006. We obtained 91 nests of four species of Trypoxylon (Trypargilum). In the laboratory, each Trypoxylon nest was sectioned longitudinally to study its architecture. The number of brood cells was counted, and the occurrence and length of vestibular and intercalary cells and the pre-closing plug space were recorded. We measured the diameter of the cane entrance, total length of the nest, length of each brood cell, maximum thickness of mud partitions and closing plug thickness. We also recorded the cell contents: the wasps, their natural enemies and the prey spiders. Mortality was assessed and the sex ratio calculated for each species. Finally, the nests were examined to help clarify the function of the vestibular cell. The nest architecture was similar in the four species, with linear brood cells located one after the other separated by mud partitions, as in other species of the subgenus Trypargilum. Forty-eight percent of the nests had vestibular cells, but only two had intercalary cells. The thickness of the mud partitions and the length of the brood cells differed among species and were related to the size of the emerged wasp. The diameter of the nest entrance was directly related to the average length of the fore-tibia. Sex ratios of all species did not deviate from 0.5. Mortality due to parasitoids (Eulophidae; Melittobia sp.) was similar among species, while the mortality due to cuckoo wasps (Chrysididae) in T. lactitarse was higher than in the other species. The presence of vestibular cells was not related either to the mortality due to natural enemies or to the orientation of the trap in the field. Spiders in the family Araneidae were the most frequently collected prey.     

The biology in Jamaica of the adults of the sphecid wasp Sceliphron assimile Dahlbom

Abstract. 1. The adult biology of the solitary mud-wasp Sceliphron assimile Dahlbom was studied in Jamaica.
2. Adults were active from sunrise until they finally settled in roosting groups a little before sunset. Nesting took place during an 8.5 h period commencing about 3 h after sunrise but individuals rarely spent > 4 h nesting per day, the remainder being spent in resting and feeding.
3. Males sought females in all places in the habitat.
4. The number of cells per nest was positively correlated to high cell density per unit area but negatively correlated to illuminance.
5. The number of pellets used to build a cell, but not cell length, was negatively correlated to the body length of the builder. There is evidence that females that build multiple nests locate them within a few metres of each other.
6. Incompletely stored cells were closed with an externally concave lamella of mud at the onset of rain or at 16.00—17.00 hours E.S.T. and never reopened the same day.
7. Like other species of Sceliphron studied in this respect S. assimile collected spiders belonging to the Argiopidae (particularly), and also mainly to the Thomisidae, Salticidae and Oxyopidae.
8. The consequences of the nest architecture on mortality and the method of building on distribution are discussed.
9. Protarrhenotoky and proterandry occur and probably influence the sex ratio through differential mortality and fecundity. A suggested interaction between the flight motor and the ovaries could regulate egg production.     

The pollination of Cymbidiella flabellata (Orchidaceae) in Madagascar: A system operated by sphecid wasps

Interactions between the terrestrial endemic Cymbidiella flabellata (Thou.) Rolfe (Orchidaceae) and flower-visiting insects were observed in a marsh on the east coast of Madagascar. The plant acted by deceit. Two large sphecid wasp species, females of Sceliphron fuscum Klug and males of Sphex torridus Sm. (Hymenoptera, Sphecidae), made frequent visits to the showy, ca. 5 cm wide, nectarless and fragrant flowers. During a visit the wasps alighted on the large, hinged labellum which they depressed while forcing their heads towards the basal cavity below the column. When the wasps withdrew they pressed powerfully down on the labellum and brushed their heads backwards against the floral sexual organs removing the pollinarium with the frons or vertex – from which position pollination took place. The wasps on average visited only two flowers consecutively and about 55% of the flowers in the orchid population received visits. About six times more pollinaria were dispersed by pollen vectors than reached stigmas and a high proportion of the flowers were aborted due to lack of pollination. Data suggest that S. fuscum , a spider hunting and mud-daubing species, is a principal pollinator. C. flabellata is interpreted as playing the role of a generalized food-flower mimic which is specialized to moist habitats where females of S. fuscum collect mud for their nests.     

Life strategy and mortality factors of Sceliphron laetum (Smith) (Hymenoptera: Sphecidae) in Australia

Mortality factors and life-history strategy central to the population dynamics of a common Australian mud-daubing wasp Sceliphron laetum have been determined by the examination of remains left behind in mud nests. A life table has been constructed for the species and details of its life cycle, parasites and predators are presented. Results suggest that the effort involved in nest construction is rewarded by a very low egg, larval and pupal mortality, and that the population size may be limited by a shortage of suitable nesting sites.     

The natural history of the mud-dauber wasp Sceliphron fistularium (Hymenoptera: Sphecidae) in southeastern Brazil

Nests of Sceliphron fistularium were obtained in Colombia and Moji Gua?u, S?o Paulo, Brazil. Complete nests consisted of 1 to 54 sausage-shaped cells, arranged side by side along a horizontal axis, and found attached to electrical wires (Colombia, n = 7) and walls (Colombia, n = 4 and Moji Gua?u, n = 4). The number of cells per nest ranged from 1 to 54, their length varying from 20.8 to 29.7 mm, and their diameter from 7.6 to 11.7 mm. Brood cells were provisioned with spiders of the family Araneidae. Only Alpaida veniliae was collected in Colombia, whereas the most frequent species found in Moji Gua?u was Micrathena swainsoni (62.0%) followed by M. acuta (23.3%). Adults emerged from June to October. The length and diameter of female and male cells were similar. Nevertheless, females were significantly larger than males. The sex ratio of individuals obtained from nests was 1.16 females: 1 male. A life table was constructed, and details of the life cycle of the wasps and parasitoids are presented. The most common mortality factors were either unknown or due to the parasitoid wasp Melittobia sp.     

Weight, volume and unbalancing: loading constraints of mud dauber wasps carrying mud balls

Load-carrying capacities of flying animals have important effects on their reproductive success, because it is expected that better performing individuals will benefit during activities such as foraging and nest building. Individually marking Sceliphron mud dauber wasp females and collecting their mud balls at three field sites, we investigated whether wasps maximize mud ball lifting and we evaluated whether the characteristics of soil affect wasp–mud ball size relationships. Sceliphron destillatorium , larger than Sceliphron spirifex , collected on average heavier and larger mud balls, and individual female body mass was positively correlated with the mass and volume of carried mud balls. Rarely mud balls reached a weight close to the theoretical maximum. On the other hand, the volume of mud balls roughly coincided on average with the theoretical maximum. A simple theoretical model showed that loss of balance during loaded flights is in part responsible for the failure to maximize the mass lifted, reducing the load-carrying capacity with a per cent value that is independent of the wasp's size. Soil characteristics also seem to affect the lifting dynamics of wasps: similar-size females carried significantly lighter mud balls in denser-soil sites. Our results showed that the volume is the strongest factor limiting mud ball carrying. The effect of such limitations, moreover, may change depending on the physical properties of the material used for nest construction.     

Morphological distance and inter-nest distance account for intra-specific prey overlap in digger wasps (Hymenoptera: Crabronidae)

Although inter-individual diet variation is common in predatory wasp populations, the factors accounting for such variation are still largely unknown. Here, we asked if paired diet dissimilarity in three species of digger wasps correlates with morphological distance and inter-nest distance, two factors previously linked to diet partitioning in vertebrates. Results sharply differed among species and generations. All sampled populations showed significant inter-individual diet variation for prey taxa, but only in half of the cases for prey size. In one generation of two species [Bembix zonata Klug and Stizus continuus (Klug)], similar-sized wasps had similar prey taxonomic spectra (and for S. continuus also similar prey size spectra), a phenomenon which probably reduces intra-specific competition. In addition, B. zonata females nesting closer to each other had more similar prey taxonomic spectra, suggesting that distant females probably hunt on different patches that harbour different prey species. For the females of a further species (Bembix merceti Parker), pairwise size difference and inter-nest distance did not affect prey dissimilarity. Both morphological distance and inter-nest distance are potentially important in shaping the overlap of individual resource use in wasps, though probably only in certain conditions such as a highly clumped distribution of nests and size-related constraints on prey selection.     

Abundance of wasps and prey consumption of paper wasps (Hymenoptera, Vespidae : Polistinae) in Northland, New Zealand

Polistine and vespine wasps were captured in Malaise traps in two fire-modified shrubland habitats of varying canopy height and composition at Lake Ohia, Northland, New Zealand. Prey consumption rates were calculated for the Asian paper wasp (Polistes chinensis antennalis) occupying these two areas of shrubland and a home garden in Whangarei, Northland. The sites were systematically searched for nests and wasp prey determined by intercepting foragers returning to nests. The Asian paper wasp predominated in the Malaise trap samples from the low- growing habitat while the German wasp (Vespula germanica) was more common in the taller vegetation type. The Asian paper wasp was more abundant than the German wasp in the samples in February and early March. Only four Australian paper wasps (Polistes humilis) and no common wasps (Vespula vulgaris) were caught. Asian paper wasps collected an estimated 15 000 prey loads per ha per season from one of the shrubland areas, and 478 000 prey loads per ha per season from the second area. These convert to estimates of 31 and 957 g per ha per season of invertebrate biomass removed by paper wasps from each habitat, respectively. The estimate for the garden site was 79 g per ha per season. Wasp nest densities varied between 20 and 210 nests per hectare. The biomass estimates are similar to average figures calculated for vespine wasps in scrubland and pasture. Both Asian paper wasps and Australian paper wasps preyed mainly on lepidopteran larvae. The cabbage white butterfly (Pieris rapae) was the most commonly collected species. Noctuid species were also well represented. Both male and female Asian paper wasps collected nectar in late March and early April.     

Biology of the solitary wasp Trypoxylon (Trypargilum) agamemnon Richards 1934 (Hymenoptera: Crabronidae) in trap‐nests

Buschini, M.L.T. and Fajardo, S. 2009. Biology of the solitary wasp Trypoxylon (Trypargilum) agamemnon Richards 1934 (Hymenoptera: Crabronidae) in trap‐nests. —Acta Zoologica (Stockholm) 91 : 426–432. Some Trypoxylon species build their nests in preexisting tubular cavities like hollow stems and beetle borings in branches. Study of the biology of these insects is relatively easy because the females of these wasps nest with enormous success in trap‐nests. The aim of this study was to investigate the abundance, seasonality and life‐history of Trypoxylon agamemnon. For capture of these insects, trap‐nests were installed in the Parque Municipal das Araucárias in araucaria forest, grassland and swamp, from December, 2001 to December, 2005. Two hundred and ninety seven nests were obtained. They were constructed more often during the summer (from December to April). The nests were built only in araucaria forest and consisted of a linear series of cells, divided by mud partitions, whose number varied from 1 to 7. Normally they have only one vestibular cell. The inner cells had been provisioned, usually with spiders of Anyphaenidae family. Sex‐ratio was strongly female biased. Its main natural enemies included Chrysididae, Ichneumonidae and Tachinidae.     

Trap-nest occupation by solitary wasps and bees (Hymenoptera: Aculeata) in a forest urban remanent

Temporal variation of solitary wasps and bees, nesting frequency, mortality, and parasitism were recorded from a remanent forest in Belo Horizonte, MG, Brazil. Wasps and bees were collected in trap-nests placed in areas with 25, 100, and 400 m2, from February to November 2004. The 137 trap-nests collected contained 11 species of wasps and bees. Wasps occupied most nests (75%). Occupation peaks occurred in March (25%) and September (26%); in June, the lowest occupation (2%) was observed. Except for Trypoxylon (Trypargilum) lactitarse Saussure, no significant correlation was found between number of occupied nests, and temperature and rainfall means. In the nests, 48% of the immature specimens died; 13% of the nests were parasitized. Total death and parasitism rates of wasps and bees differed significantly.     

Factors controlling the distribution in Jamaica of Pachodynerus nasidens (Latr.) (Hymenoptera: Eumenidae)

Pachodynerus nasidens (Latr.) is an inquiline in the disused cells of Sceliphron assimile Dahlbom (Sphecidae) and Eumenes colona Saussure (Eumenidae) in Jamaica. Within the area of distribution of its hosts it is virtually absent where the essential resources of water and of leaf-mining, flower-feeding or leaf-rolling caterpillars on bushes are further than 80 m from the nesting site. Its use of host cells is reduced where mean annual precipitation is less than 1200 mm and where altitude is less than 100 m. In trap-nests it can be collected only in shaded and (less frequently) in partly-shaded localities. Of six other inquilines also found, only Trypoxylon texense Saussure (Sphecidae) was sufficiently numerous to be an important competitor for host cells but evidence shows its competition was unimportant to Pachodynerus nasidens. High percentage mortality resulting from Melittobia chalybti Ashmead (Eulophidae) on P. nasidens did not limit utilization of host cells. During drought, fecundity of P. nasidens dropped from 14.0 (± 2.9) to 7.0 (± 1.4) eggs per female and this may have brought about local extinction and hence low utilization of host cells. Drought reduced longevity and the rate of oviposition, but had no effect on the speed of provisioning.     

Nesting biology of Pareumenes quadrispinosus (de Saussure, 1855) (Hymenoptera: Vespidae: Eumeninae) in trap nests in North Vietnam

Nests of Pareumenes quadrispinosus (de Saussure, 1855) were obtained at Me Linh Station for Biodiversity (323 nests) and Tam Dao Town (283 nests), Vinh Phuc Province, as well as at Phu Luong, Thai Nguyen Province (9 nests) and Kim Boi, Hoa Binh Province (62 nests). The wasps nested in segments of bamboo canes and reed stems, 5 to 18 mm in internal diameter. Each nest consisted of a linear series of one to four cells, separated by mud partitions. Brood cells were provisioned with caterpillars and eggs were attached to the ceiling of the cells by thin threads. The life history and sex ratio of this species nesting in trap nests in North Vietnam were recorded from mid-April to last October. The species is multivoltine, with likely up to four generations per year. It has two alternative life histories (diapause and direct development) and overlapping generations. The sex ratio is strongly female-biased. Only 46% of the provisioned cells were successful; the others were damaged by nine parasitoid species or died during development for unknown reasons.     

Contrasting Patterns of Species Richness and Composition of Solitary Wasps and Bees (Insecta: Hymenoptera) According to Land‐use

Several species of arthropods inhabiting forest fragments interact with managed areas. The importance of such areas to biodiversity conservation, however, is not well established. Communities of solitary wasps and bees (Insecta: Hymenoptera) play a key role in agroecosystem functioning and they have been used in studies of biodiversity assessment in different land‐use types. We aimed to assess patterns of species richness and composition of solitary wasps and bees over a 1‐yr period in a gradient of decreasing land‐use intensity formed by pastures, alley croppings, young fallows, and old fallows using trap nests. Old fallows had the highest species richness of wasps and bees, harboring all bee species and 86 percent of wasp species occurring in the region, while the remaining land‐uses had similar species richness. Vegetation structure (tree richness) and relative humidity explained most of the variance for the species richness of wasps. For bees, however, there was no influence of environmental factors on the community among land‐use types, indicating better adaptability of this group to environmental variations related to land‐use. The composition of solitary wasp communities (but not those of bees) differed among land‐use types, and the occurrence of rare species in most cases was restricted to old fallow sites. In conclusion, the community of solitary wasps and bees is contingent on land‐use, with solitary wasps more sensitive to anthropized areas. For both groups, less anthropized areas harbor a greater richness and number of rare species while more intensively managed land‐use types harbor higher abundances.     

Nearnest behavior of a solitary muddaubing wasp,Sceliphron caementarium (Hymenoptera: Sphecidae)

Mud dauber wasps (Sceliphronspp.)construct nests by sequential flights to gather mud and return it to their aerial nests. Individual S. caementariumdiffer in the mean time spent in four states of construction: approach, daubing, inspection, and departure. Placing a novel object near nests or replacing a white object by a black one resulted in an increase in individuals' approach times but no change in departure times. Removal of objects or replacing a black object by a white one had no effect. A change in the color of objects near nests elicited increased approach times but did not affect departure. S. caementariumappears to memorize three-dimensional objects in the nearnest environment, and changes in the nearnest environment are learned during the approach flight to the nest. The frequency of significant responses to all manipulations decreased with successive visits by the wasps, suggesting habituation to nearnest changes.     

The biology of the mud-wasp Zeta abdominale (Drury) (Hymenoptera: Eumenidae)

The adult female nesting behaviour and biology of the neotropical mud-wasp Zeta abdominale (Drury) was studied in Jamaica. The cell-building behaviour was generally similar to that of Eumenes, but Zeta closed the apical funnel of the cell by moistening and re-moulding it into a plug. Each nest was built by a solitary female, who often built several small, mostly one-celled nests. Females efficiently used mud in cell-building, and small nests were advantageous, in needing less mud per cell and incurring a lower rate of predation than larger nests. Cellwall construction and provisioning were each completed in < 3 h, but a long pause between these activities, probably for feeding, delayed cell completion to 2.33 ± 1.0 days.
The number of active nesting females during a 10-h cycle was influenced by the time of day and weather. A relatively dense population had about 6.4 females ha^-1, whose age distribution, longevity and fecundity were estimated.     

Diversity and community structure of social wasps (Hymenoptera: Vespidae) in three ecosystems in Itaparica island, Bahia State, Brazil

We studied the structure and composition of communities of social wasps associated with the three insular ecosystems: mangrove swamp, the Atlantic Rain Forest and the 'restinga'- lowland sandy ecosystems located between the mountain range and the sea. Three hundred and ninety-one nests of 21 social wasp species were collected. The diversity of wasps found in each ecosystem was significantly correlated to the diversity of vegetation in each of the three physiognomies, (r(2) = 0.85; F(1.16) = 93.85; P < 0. 01). The Tropical Atlantic Forest physiognomy had higher species richness (18 species), followed by the restinga (16 species) and the mangrove (8 species) ecosystems.     

Nesting activity of cavity-nesting bees and wasps is lower in small-scale apple orchards compared to nearby semi-natural habitats

1. Commercially reared cavity-nesting bees have been studied mainly in large, intensively managed orchards. However, knowledge on wild cavity-nesting bee and wasp communities and their potential limitations in smaller orchards remain insufficient.
2. We compared the colonization rate of trapnests, nesting success, parasitism and response to flower resources of cavity-nesting bees and wasps between apple orchards and nearby semi-natural habitats (SNHs).
3. Trapnests were placed in orchards and neighbouring SNHs. Colonization dynamics were studied and herbaceous flower resources were estimated. Furthermore, nest and brood cell quantity, number of alive offspring and nest parasitism rate were assessed.
4. We found a higher colonization rate in the SNHs than in the orchards. Both bees and wasps made more nests, completed more brood cells and had a higher number of alive offspring in the SNHs. The number of bee nests in the orchards showed a positive correlation with the species richness of the flowering plants. The nest parasitism of wasps was higher in the SNHs.
5. Apple orchards in the studied small-scale system were generally less colonized by cavity-nesting hymenopterans than nearby SNHs that can be important reservoirs of these ecosystem service provider hymenopterans. Our results highlight the importance of diverse flowering herbaceous vegetation in the understory that increased the number of bee nests in orchards and that could have a positive effect on the nesting activity of the bee species active in summer. Therefore, management practices that support flowering plant species in the understory vegetation are highly recommended in such orchards.

     

Nesting ecology of the wasp Sceliphron destillatorium (Illiger, 1807) (Hymenoptera,Sphecidae) in the Crimea

The nests of Sceliphron destillatorium in the Crimea were mainly built in attic spaces of houses and in various uninhabited buildings, and consisted of 3–39 (on average 16.5) cells. Twelve species of spiders from 11 genera of 4 families with predomination of Araneidae and Oxyopidae were recorded as prey. One nest cell contained 4–13 (on average 7.9) spiders, mostly adult ones. Successful development of S. destillatorium progeny was recorded in 48.6% of the cells; 26.5% of the progeny died from parasites: Amobia pelopei (16.0%), Chrysis taczanovskyi (4.3%), and Melittobia acasta (6.2%); 24.9% of the progeny died for unknown causes at the egg (13.0%) or prepupal (11.9%) stage. Nests of 17 other wasp and bee species from the families Pompilidae (2 species), Vespidae (4), Colletidae (1), and Megachilidae (10 species) were found in abandoned nest cells of S. destillatorium. The abundance of S. destillatorium has noticeably decreased in the last ten years, possibly due to immigration of a congener, S. curvatum, which has more diverse trophic links and a significantly higher rate of nesting success.     

Further evidence of the Asian mud-daubing wasps in Europe (Hymenoptera: Sphecidae)

We report the further south‐eastward range extension of the invasive Asian mud‐daubing wasp, Sceliphron curvatum (Smith), initially introduced into Austria in the late 1970s. We document its presence in the central Balkan Peninsula from 1997 onwards, and we discuss the circumstances and course of its recent expansion in the area. We also report the first finding of another Asian species, Sceliphron deforme (Smith), in Europe, and we consider various aspects of this case, given the possibility that the record from southern Montenegro represents a successful introduction.     

Cavity-nesting bees and wasps (Hymenoptera: Aculeata) in a semi-deciduous Atlantic forest fragment immersed in a matrix of agricultural land

Cavity-nesting bees and wasps (Hymenoptera: Aculeata) have been showed to be suitable models to investigate the effects of forest fragmentation and human land use. Those studies are particularly pertinent when considering fragmented ecosystems such as the Atlantic semi-deciduous forest in Brazil. We investigated the changes in composition, nest abundance, and mortality of cavity-nesting bees and wasps over edge-center forest fragment immersed in a matrix of agricultural lands in southeastern Brazil. Trap-nests (bamboo canes and cardboard tubes) were set in nine sampling stations in three different zones in the study site: three sampling stations at the forest edge; three at 250 m away from the edge and another three at 500 m away from the edge. Nests were monitored monthly for 2 years (from June 2011 to May 2013). A total of 942 nests (706 built by 16 bee species; 236 from 18 wasp species) were collected in the fragment. A significant change over gradient edge-center was observed on the parameters analyzed. The Non-metric Multidimensional Scale analysis showed that 72% of the species (host and natural enemies) that present more than ten records were associated with the forest edge. Furthermore, the highest values of the abundance of nests, parasitism, and mortality were recorded in the edge. In spite of being surrounded by farmlands, the fragment hosts a great diversity of trap-nesting wasp and bee species. Our findings demonstrate that forest edges are important habitats to maintain communities of cavity-nesting bees and wasps.