Inquilines of Brachymenes dyscherus nests with special reference to Monobia schrottkyi (Hymenoptera,Vespidae, Sphecidae)

Sixty-four inactive nests of the solitary mud-daubing wasp Brachymenes dyscherus, reused by 5 inquiline species, were collected at Fazenda Santa Carlota, Cajuru, S?o Paulo, Brazil in 1995 and 1996. Monobia schrottkyi used 52 nests; among the 717 cells available for use, 502 were reused. The number of cells per nest varied from 3 to 24; 1 to 16 individuals emerged from September to April (154 males and 112 females). Forty-six cells were parasitized by Melittobia sp. (n = 44) and Ichneumonidae (n = 2). Monobia curvata used 3 nests; among the 50 cells available for use, 38 were reused and 15 males and 8 females emerged from August to November. Three cells were parasitized by Ichneumonidae. Montezumia petiolata occupied 1 nest; among the 8 available cells, 7 were reused and 2 males and 3 females emerged in September. Podium denticulatum used 2 nests; the 20 cells available for use were reused and 11 males and 4 females emerged in August. Trypoxylon rogenhoferi used 5 nests that had 65 available cells; 48 of them were reused, from which 19 males and 11 females emerged from September to November. Three cells were parasitized by Ichneumonidae (n = 2) and Chrysididae (n = 1).     

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.     

Notes on the biology of Trypoxylon (Trypargilum) opacum Brèthes (Hymenoptera; Crabronidae) in Southern Brazil.

The present study investigated the abundance, seasonality and various life-history traits of Trypoxylon (Trypargilum) opacum. Using trap-nests, 320 nests of T. opacum were collected in the Parque Municipal das Araucárias in Southern Brazil (25 degrees 23' 36" S and 51 degrees 27' 19" W) over a 3 year period. Nesting was more frequent during the warm season. Nests consisted of a linear series of 1 to 8 brood cells separated by mud partitions, usually followed by an empty vestibular cell and final-closure mud plug. Brood cells were most commonly provisioned with spiders of the family Araneidae. Sex-ratio was strongly female biased, 3.4:1 females:males. Natural enemies attacking nests T. opacum included chrysidids, ichneumonids, sarcophagids, bombyliids and ants.     

The biology of the eumenid mud-wasp Pachodynerus msidens in trapnests

Abstract. 1. The biology of the eumenid mud-wasp Pachodynems nasidens (Latr.) was studied in trapnests.
2. Females nested in traps placed in the shade and some nested in the same traps from which they had emerged.
3. The nesting behaviour and nest structure were generally similar to those of other eumenids that nest in borings, but a temporary crescent-shaped plug at the nest entrance and the use of both dry soil and mud for nest-building seems unique to P.nasidens .
4. Like most other eumenids, P.nasidens collected caterpillars, mainly Pyral-idae, Olethreutidae, Alucitidae and Thyrididae.
5. In linear nests, the innermost cells contained females and the outermost cells males, resulting in proterandry. One female can make several nests, each showing proterandry.
6. Female immatures were larger and took more time to develop than males. Also, their cells were larger and stocked with more food than male cells, hence needing more time to be provisioned.
7. The greater 'cost' to produce a female and a sex ratio biased toward females in short traps and about unity in longer traps, leads to a comment on parental investment.     

Maternal investment in a bee species with facultative nest guarding and males heavier than females

1. Maternal investment can be influenced by several factors, especially maternal quality and possibilities for future reproduction. Mass provisioning Hymenoptera are an excellent group for measuring maternal investment because mothers distribute food sources to each brood cell for each offspring separately. Generally in aculeate Hymenoptera, larger females produce larger offspring and invest more in female offspring than in male offspring. 2. This study investigated patterns of maternal investment in Ceratina chalcites, which has an uncommon type of sexual size dimorphism in Hymenoptera: on average, males are heavier than females. It was found that larger females produce a significantly higher proportion of male offspring, as males are the costlier sex in this species. 3. Facultative nest guarding by females was observed. Females can guard offspring until adulthood, as is typical for bees of genus Ceratina (34.43% of nests); however, in the majority of cases (65.56% of nests), females plug and abandon the nest. Significant differences were found in the amount of investment between guarded and unguarded nests. Guarded nests had a greater number of provisioned brood cells and a higher proportion of male offspring. It is suggested that mothers have two facultative strategies – either she makes a large investment in the offspring of one nest or she abandons the first nest and carries out a second nesting elsewhere.     

Females of the European beewolf preserve their honeybee prey against competing fungi

1. Females of the European beewolf Philanthus triangulum (Hymenoptera, Sphecidae) provision brood cells with paralysed honeybees as larval food. Because brood cells are located in warm, humid locations there is a high risk of microbial decomposition of the provisions. Low incidence of fungus infestation (Aspergillus sp.) in nests in the field suggested the presence of an anti‐fungal adaptation. 2. To test whether the paralysis caused the protection from fungus infestation, the timing of fungus growth on bees that were freeze‐killed, paralysed but not provisioned, and provisioned regularly by beewolf females was determined. Fungus growth was first detected on freeze‐killed bees, followed by paralysed but not provisioned bees. By contrast, fungus growth on provisioned bees was delayed greatly or even absent. Thus, paralysis alone is much less efficient in delaying fungus growth than is regular provisioning. 3. Observations of beewolves in their nests revealed that females lick the body surface of their prey very thoroughly during the period of excavation of the brood cell. 4. To separate the effect of a possible anti‐fungal property of the brood cell and the licking of the bees, a second experiment was conducted. Timing of fungus growth on paralysed bees did not differ between artificial and original brood cells. By contrast, fungus growth on bees that had been provisioned by a female but were transferred to artificial brood cells was delayed significantly. Thus, the treatment of the bees by the female wasp but not the brood cell caused the delay in fungus growth. 5. Beewolf females most probably apply anti‐fungal chemicals to the cuticle of their prey. This is the first demonstration of the mechanism involved in the preservation of provisions in a hunting wasp. Some kind of preservation of prey as a component of parental care is probably widespread among hunting wasps and might have been a prerequisite for the evolution of mass provisioning.     

The biology of the primitively eusocial Augochloropsis iris (Schrottky, 1902) (Hymenoptera, Halictidae)

Summary: This work investigated Augochloropsis iris, its annual colony cycle, brood size and survival rate, caste differentiation, and sex ratio, and is the first detailed account of a clearly eusocial species of this genus. The population studied is located in the Campos do Jordão State Park, São Paulo, Brazil. The annual colony cycle extends from August to March and consists of three phases of cell provisioning separated by two phases of inactivity, and followed by an emergence of future queens and males. Provisioning during the first phase is carried primarily out by solitary females. The daughters, after emerging from the cells, remain in the natal nests, carrying out foraging activities, while the mother engages in reproduction. New nests are initiated during each of the provisioning phases by solitary females, principally by females from the second-phase brood which, soon after emerging from the cells, leave their natal nests to found their own nests, which they provision during the third phase. The females resulting from the third-phase brood in general mate and excavate their own nests, in which they diapause, with provisioning delayed until the following August. On average, the queens are significantly larger (5%) than the workers. In general, the workers do not have developed ovaries, but all are mated. Kin selection can be accepted as the selective force responsible for worker behavior of A. iris in eusocial colonies when the queen has mated once and semisocial colonies if the queen mated only once. The percentage of males produced in the first, second and third broods and in the brood of new nests founded by solitary females active in the second and third phases was: 20.7%, 22.2%, 13.3% and 0.0% respectively. The resultant sex ratio of the third brood suggests that the third-phase workers of eusocial nests are at least in partial control of their colony's sex ratios, in cases where the queens mated only once.     

A report of progressive provisioning in a stink bug,Parastrachia japonensis (Hemiptera: Cydnidae)

The majority (75%) of femaleParastrachia japonensis (Hemiptera: Cydnidae), while caring for 1st and 2nd instar nymphs, foraged for and provisioned nests with drupes of the host plant,Schoepfia jasminodora (Olacacae), which the young then fed on. The maximum number of drupes found in a given nest was 27. Females could travel as fast as 61.4 cm/min while carrying drupes that were nearly double their weight, and were directly observed to travel as far as 10 m when encumbered with a drupe. It was found that nests which were far from the food source were provisioned with at least as many drupes as those nests that were within the drupe range. While females could not distinguish their own eggs from others, apparently they could distinguish their own nests containing their nymphs. Eggs failed to survive in the absence of a female, however, a small number of nymphs reached adulthood even in the absence of a female when drupes were provided. This report represents the first direct observation of progressive provisioning by a phytophagous hemipteran under field conditions.     

The nesting of Osmia rufa (L.) (Hymenoptera, Megachilidae) in the Crimea: Structure and composition of nests

The structure and composition of nests of Osmia rufa have been investigated. The weight of the septa between the cells increases regularly from the first to the last cell, whereas the length of cells and weight of the pollen loaf decrease. The difference of weight between cells of males and those of females is sharper. The number of cells and weight of cocoons with adults decrease in the series of nests built by the same female during the nesting season, and the sex ratio shifts to males. Abundant food resources facilitate an increase in the average weight of the offspring, the number of cells, and shift of the sex ratio toward females. The mechanism of the sex ratio regulation in O. rufa nests includes three consecutive elements. The key element is the presence of a marker of the switching to making low-weight pollen loafs. This marker is the moment of the “overloading” of the last cell in a row of cells intended for future females. Daughters of large females are smaller, and those of small females, larger than their mothers. The probable cause of this discrepancy is the allometric relation between the female’s weight and its working capacity.     

Nesting biology and nest re-use ofEulaema nigrita (Hymenoptera: Apidae,Euglossini)

Summary The nesting behavior of the euglossine beeEulaema nigrita was observed in the laboratory after being transferred from three nests to observation boxes. Nests were re-used by successive generations with more than one female working in each re-use process. Associated females were always of the same generation. All females that shared a nest foraged for construction materials (mud, excrement and resin) and each constructed, provisioned and oviposited in her own cells. The number of cells constructed by each female ranged from one to 23. Females stayed in the nests for periods ranging from 15 to 59 days during the hot and wet season and from five to 78 days during the cool and dry season. The egg-to-adult period was related to climatic conditions, and in all re-use processes it was longer than the time of residence of the females in the nests. The meloid beetleMeloetyphlus attacephalus was the only nest parasite. Due to the attack method employed by this parasite, the presence of more than one female in the nest did not result in improved nest defense.     

Group nesting and individual variation in behavior and physiology in the orchid bee <Emphasis Type="Italic">Euglossa nigropilosa</Emphasis> Moure (Hymenoptera,Apidae)

The Euglossini are a key group for studying the traits that promote or hinder highly social behavior in bees because it is the only tribe in the Apine clade without large colonies or females with distinct life histories, e.g. queens and workers. There have been few studies on behavior of orchid bee females in nests because these nests are not found easily. Taking advantage of the relatively high abundance of Eg. nigropilosa nests at Reserva Natural La Planada, Colombia, we examined social behavior of Eg. nigropilosa individuals in five nests (3 original and 2 reused) for nine months. We report this species to have the largest colonies known for Euglossa, with nests reaching up to 22 individuals, and all nests containing more than one female bee from the same generation. These nests presented many traits that correspond to communal insect colonies. No generational overlap and no cooperative brood care were detected. We examined natural enemies and resource limitation as important factors for group nesting. We examined parasitoid attacks to cells in a nest with females and one without females. We also searched for nesting locations and examined nest re-use as indicators of nest site limitation. Lastly, we examined behavioral and physiological differences among females in the same nest. Such differences could be the bases for evolution of alternative life histories among group living females. We examined extent of ovary development and oviposition rates in similarly aged females in the same nest. We found large variation in reproductive effort of young females. We also examined differences in resin foraging and cell usurpation behaviors. Behavioral specialization was observed, with some individuals bringing only resin to the nest. Inside the nests, bees had territories in which they constructed and defended cells. This territoriality may be a defense against usurpation of provisioned cells by nest mates. Received 10 December 2007; revised 2 May 2008; accepted 7 May 2008.     

Nesting biology of the potter wasp Rhynchium brunneum brunneum (Fabricius, 1793) (Hymenoptera: Vespidae: Eumeninae) in North Vietnam

Rhynchium brunneum brunneum (Fabricius, 1793) is a common species using trap nests in North Vietnam. The females chose the nest traps with diameters ranging from 5.5 to 17 mm. Nests consisted of a linear series of one to eleven brood cells separated by mud partitions. Brood cells were provisioned with caterpillars, and eggs were attached to the ceiling of the cells by a thin filament. The life history and sex ratio data of this species were recorded from April to early November. Its sex ratio is strongly male-biased, being multivoltine, likely with four generations per year, the last one overwintering in the prepupal stage. Nesting activity of the species was described with major activities such as nesting site selection, oviposition, prey collecting, and applying cell material. Only 53.3% of the provisioned cells were successful; the others were damaged by six parasitoid species or died during development for unknown reasons.     

Pre-ovipositional maternal care alleviates food stress of offspring in the flower beetle <Emphasis Type="Italic">Dicronocephalus wallichii</Emphasis>

Unlike most other flower beetles, females of Dicronocephalus wallichii exhibit nesting behaviour. The female constructs a burrow in the soil, cuts dead plant leaves into small pieces to provision the nest, and then lays one egg inside the nest. Hatched larvae have been thought to feed on the nest materials prepared by their mothers, but the effects of pre-ovipositional care on larval performance have not been tested. The hatched larvae were found to stay in the nest for 15–30 days until they consumed the nest materials. We examined whether the presence of provisioned nests enhanced larval performance under both benign and food-stress conditions. With high-nutrient soil, larval survival rate and growth speed were not affected by the presence of provisioned nests. By contrast, with low-nutrient soil, mortality of the larvae was much higher in the absence than in the presence of provisioned nests. The growth speed of larvae with nests located in low-nutrient soil was as high as those reared in high-nutrient soil. These results indicate that females alleviate the food stress of larvae during their initial developmental stage by constructing provisioned nests.     

Nesting biology of Centris flavifrons (Friese) (Hymenoptera: Apidae, Centridini), one of the main pollinators of Byrsonima crassifolia L. Kunth in Maranhão, Brazil

The Centridini has almost 176 species distributed mainly in the tropic regions of America. Although they are considered key pollinators in the maintenance of many vegetal species, data about their bionomics are restrict. Nesting activity is known for 11 species, out of the 21 that are considered pollinators of murici, Byrsonima crassifolia L. Kunth, a valuable biomonitoring specie. A study of the nesting biology of Centris flavifrons (Friese) was conducted in the state of Maranh?o, Brazil, during the active period of the adults (May through December). Nests were aggregated. The females excavated their nests on flat surfaces of hard soils. Fifteen nests were dug and we only found cells in six of them. The nests architecture consisted of a single unbranched tunnel, with only one cell in the vertical position at the end, which was 25 cm to 50 cm away from the entrance. Nocturnal activity was observed in the nests building. The pollen analysis of the contents of four cells allowed to identify 23 floral species, six of them Malpighiaceae. Six floral species were registered visiting C. flavifrons by the first time: Lecythis lurida (Miers) Mori, Hymenea courbaril L., Myrcea sp., Protium sp., Tetrapterys sp. and Thalisia sp.     

The nesting biology of the bee, Osmia dimidiata Morawitz, 1870 (Hymenoptera, Megachilidae) in the Crimea

The structure and composition of Osmia dimidiata nests were studied based on the material of 133 nests obtained from trap-nests in five localities of the Crimea. The nests contained from 1 to 9 cells (on average, 2.2), separated with partitions made of masticated leaves. Most of the cells had a massive hemispherical bottom and a thin flat cover. The final plug had a structure similar to the cell bottom. The cells occurred singly in the nest cavity or were arranged in rows of 2 or 3 cells separated by galleries. The diameter of the occupied cavities was positively correlated with the fraction of the females in the progeny and with the mass of the cocoons, but negatively correlated with the cell length. The cells with females were 1.5 times as long as those with males. The cocoons with females were twice as heavy as those with males. The peculiar characters of the nest structure of O. dimidiata may mean that the typical nesting substrates of this species are abandoned cells of other bee and wasp species. The characteristic mechanism of estimating the mass of the pollen loaf stored in the cells and determining the brood sex ratio has evolved in the O. dimidiata due to its tenantry. This mechanism is based on two constants: the sex-linked cell length and the fixed distance between the pollen loaf and the cell cover. When choosing the nesting cavities, the female prefers broader and longer tubes for cells with females and narrower and shorter ones for cells with males. The overall sex ratio of the progeny was male-biased (1 ♀: 2.5 ♂) and depended on the food supply abundance. The adults of O. dimidiata fly in the Crimea from the last decade of May until the end of July. Hibernation occurs at the adult stage in the cocoons. Females collect pollen from flowers of Asteraceae or, rarely, Fabaceae. The nests may be destroyed by Melittobia acasta, Monodontomerus aereus, M. obscurus, Sapyga quinquepunctata, Stelis phaeoptera, and Trichodes apiarius; 21% of the progeny died from these enemies, and 22%, due to other factors. The previously proposed synonymy of Pseudosmia taurica Radoszkowski, 1874 (nec Osmia taurica Radoszkowski, 1887) and O. dimidiata is rejected.     

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.     

Blue structural coloration of male eastern bluebirds Sialia sialis predicts incubation provisioning to females

Plumage coloration has been suggested to serve as an honest signal of benefits that males provide to females. One benefit proposed for females that choose to mate with elaborately colored males is that such males might provide more food resources to the females. To test this hypothesis, we investigated the relationship between the rates at which males provisioned incubating females and the structural ultraviolet (UV)/blue coloration and melanin-based chestnut coloration of male eastern bluebirds Sialia sialis , a sexually dichromatic songbird in which coloration has been shown to be sexually selected in males. We found that males with brighter UV/blue coloration provisioned incubating females more often than did drabber males. Melanin coloration, however, was not correlated with provisioning rates. Moreover, provisioning rates were correlated with the length of time that females spent off the nest, indicating an important benefit of increased male provisioning. These data support the hypothesis that female bluebirds receive direct resource benefits by pairing with males with bright structural coloration.     

Few, small, and male: multiple effects of reduced nest space on the offspring of the solitary wasp, Euodynerus (Pareuodynerus) posticus (Hymenoptera: Vespidae)

The size of the preexisting wood cavities used as nests by aculeate Hymenoptera is expected to have consequences on fitness parameters such as offspring number and size. We evaluated the consequences of using small and large (three-times more voluminous) trap-nests by the solitary wasp, Euodynerus (Pareuodynerus) posticus (Herrich-Schaeffer). Following life-history and sex allocation theories, a number of non-mutually exclusive hypotheses were formulated: i.e. small nests either produce smaller or fewer offspring and/or more males, the cheaper sex. Wasps built about 28% more, but shorter brood cells in large nests, although their volume was still much higher in large nests. Adult males had smaller body size in small nests, but female size did not differ between large and small nests, possibly as an adaptive response against the future higher foraging costs of size-reduced females. Sex-ratio was often biased towards males in small nests. Mortality did not differ between large and small nests. We conclude that E.?(P.) posticus females would benefit from using larger nests, but that the sex-ratio would be probably overall unbalanced if females would not use also smaller, male-oriented tunnels.     

The Significance of the Vestibular Cell in Trap Nesting Wasps (Hymenoptera: Crabronidae): Does its Presence Reduce Mortality?

In a study carried out with the trap-nesting solitary wasp Trypoxylon attenuatum (Hymenoptera: Crabronidae) in 2000, we analysed the significance of different nest characteristics, like the vestibular cell and empty intercalary cells, and its role in the reduction of mortality. Analysis of the presence of the vestibular cell suggested that it represents a nest completion structure, whose presence reduces mortality in the initial stages (M1) but does not affect that due to chrysidid parasitoids (MP). The length of such vestibular cell was found to depend mainly on the space between the last provisioned cell and the exterior, pointing to a possible role in the reduction of the remaining space that could be used by other females to establish a nest exterior to the completed one. The empty intercalary cells were smaller than the vestibular cells, did not affect M1 or MP mortality rates in the nest, and exhibited an “aggregated” pattern of occurrence. This suggests that they could be the result of “abnormal” behaviour by the female owning the nest. The total mortality rate decreased with the increase in the number of cells in the nests, also being greater in nests established at low heights above the ground. M1 was lower in the innermost cells, while MP increased towards the interior and in the nests with more cells. The distribution in the nests of cells parasitized by Trichrysis cyanea (the main natural enemy found in the wasp population studied) reflects an “aggregated” pattern, suggesting repeated attacks against certain nests.     

Mating system and mate choice of Tengmalm's Owls Aegolius funereus

The mating system and mate choice of Tengmalm's Owls were studied in relation to population fluctuations of the staple food (voles) for seven years in western Finland. Three age classes of owls were differentiated: first-year, second-year and older owls. Despite a surplus of males, 11 % of them showed simultaneous bigyny in peak vole years. The mean distance between primary and secondary nests was 1158 m, and usually there was a free nest-box between the two nests. Because primary nests produced more fledglings than secondary ones and secondary nests produced fewer fledglings than simultaneous or even eight-days-later monogamous nests, this bigyny could be best explained by the 'deception' hypothesis.
In successive biandry, females deserted their first brood when young were still in the nest, thereby transferring the burden of raising the young to their males. The tendency of assortative mating by age (more yearling x yearling and + 2-year-old ×+ 2-year-old pairs than expected by chance) showed that females chose older males when these were available.