Philopatry, nest choice, and aggregation temporal–spatial change in the digger wasp Cerceris arenaria (Hymenoptera: Crabronidae)

Studying temporal and spatial changes of aggregations of digger wasps through nesting seasons is interesting because of its link to social evolution via a semi-social pathway, but information about this topic is scarce. An aggregation of Cerceris arenaria Latreille was studied during 1997–1999 and for a short period in 2001. The colony grew in area and number of nests through the first three seasons, but the aggregation reduced in 2001, and this decrease was confirmed by a count of nests made in 2003 and 2005. The positions of the nest entrances remained almost constant over the years, at least in high-nest-density areas, because of the repeated use of the same burrows from which they emerged. This fact permits the population to exploit for many years a restricted area and could act as a nest-density-regulation method for fossorial species that rarely dig new nests, preventing an excessive nest density. The newly emerged females did not dig new nests, showed a high philopatry in the choice of their first nest, and preferred to look for other nests to occupy close to the ones recently abandoned (mainly for an undergone usurpation by a conspecific female). Philopatry, along with lack of new nest digging and position-dependent nest choice, is probably an important factor maintaining spatial stability of the aggregation through the years and could represent a first step in the evolution of a higher sociality in apoid burrowing Hymenoptera.     

The control of nest depth in a digger wasp (Sphex ichneumoneus L.)

Golden digger wasps, Sphex ichneumoneus L. (Sphecidae), are a solitary, ground-nesting species that dig burrows to particular depths in the soil. I develop and evaluate alternative hypeses about the mechanisms controlling digging behaviour. By altering the wasps' burrows as thare digging, I show that they are not digging for some prescribed length of time nor are they diggingtil they reach some suitable environmental characteristic deep in the soil. Rather, they appear be digging until they reach a particular tunnel length, making corrections if the tunnel is too shallor too deep. This distance can be altered somewhat by surface environmental conditions.     

Nest defense behavior against ant attacks in post-emergent colonies of wasp Mischocyttarus cerberus (Hymenoptera, Vespidae)

The primitive eusocial wasp Mischocyttarus cerberus forms colonies of independent foundation, without morphological differentiation among castes. Ants are natural enemies of the social wasps and defending the wasps’ nests involves chemical and active defense strategies. The aims of this work were to verify the kind of defense the wasps use most frequently in post-emergent colonies of M. cerberus. We also observed whether the nest was abandoned during the ant attack and whether any relationship existed between the forms that colony defense took and the number of adults, the number of cells, and the number of immature wasps. The study was carried out on the campus of Universidade Estadual Paulista of Rio Claro, São Paulo, Brazil. The 23 nests under study were mapped weekly, and 68 bioassays were performed by simulating ant attacks against the nests. The results showed that wasps used both active and chemical strategies for nest defense, and the PCA analysis showed that the aggressive behaviors of biting the ant, wings vibrating, gaster hitting, and abdomen pumping were the dominant terms; the PCA correlation values were 2.70, 2.54, 1.64, and 1.63, respectively. The colonies in pre- and post-male substages with few immature wasps and the nests in post-male substage with one adult were more correlated with the nonaggressive behaviors of hiding, staying immobile, and flying; their PCA correlation values were 3.12, 2.56, and 1.77, respectively. These results show that the number of immature wasps is an important factor in the kind and in the intensity of the defense behavior against ant attacks.     

Notes on the prey,nesting behaviour and natural enemies of three Bembix sand wasps (Hymenoptera: Crabronidae) in the Iberian Peninsula

Bembix is a cosmopolitan genus with more than 300 species distributed all over the world. The females of these wasps dig burrows in the ground and hunt for flies to feed their larvae. Current knowledge of the nesting behaviour of most Palaearctic species (around 50) is limited. In this study, we provide data on the nest structure, nesting activity, natural enemies and prey captured by three Bembix sand wasps present on the Iberian Peninsula: B. zonata, B. flavescens bolivari and B. merceti. We also analyze the prey spectrum of the three species, comparing our data with those available from previous studies. B. zonata exhibits the greatest selectivity index (and the narrowest niche width), capturing mainly Syrphidae to provision its nests. B. merceti shows the greatest niche width in comparison with the other two species. The inter-annual differences in the diet of B. merceti are important and are probably due to the ability of this wasp to change from one prey resource to another, depending on its availability.     

Incubation failure and nest abandonment by Leach's Storm‐Petrels detected using PIT tags and temperature loggers

ABSTRACT The nocturnal activity of burrow‐nesting seabirds, such as storm‐petrels and shearwaters, makes it difficult to study their incubation behavior. In particular, little is known about possible differences in the incubation behavior of adults at successful and unsuccessful nests. We combined the use of passive integrated transponder (PIT) technology and nest‐temperature data loggers to monitor the incubation behavior of 10 pairs of Leach's Storm‐Petrels (Oceanodroma leucorhoa). The mean incubation bout length was 3.31 ± 0.59 (SD) days for individual adults at successful nests (N= 4) and 1.84 ± 1.16 d for individuals at unsuccessful nests (N= 6). Mean bout length for pairs in successful burrows (3.51 ± 0.56 d) did not differ significantly (P= 0.07) from that for pairs in unsuccessful burrows (1.80 ± 1.20 d), perhaps due to one failed nest with a high mean bout length (4.15 d). The total number of incubation bouts per parent (4.3 ± 1.9 bouts) did not differ with hatching success. Adults whose nests failed repeatedly exhibited truncated incubation bouts (< 12 h) prior to complete nest failure and were more likely than successful parents to make brief visits to nearby, occupied nesting burrows. Our results suggest that the decision by Leach's Storm‐Petrels to abandon a nest is not an abrupt one. Rather, failed nesting attempts may be characterized by truncated incubation bouts where individuals pay the energetic cost of travel to and from the burrow, but do not remain long enough to successfully incubate the egg.     

First evidence of wasp brood development inside active nests of a termite with the description of a previously unknown potter wasp species

Potter wasps (Vespidae: Eumeninae) are known to exhibit not only sophisticated preying strategies but also a remarkable ability to manipulate clay during nest building. Due to a mixture of plasticity in building behavior and flexibility in substrate preferences during nest building, the group has been reported nesting in a variety of places, including decaying nests abandoned by termite species. Yet, evidence of wasps nesting inside senescent termite mounds is poorly reported, and to date, accounts confirming their presence inside active colonies of termites are absent. Here, we address a novel intriguing association between two species from the Brazilian Cerrado: a previously unknown potter wasp (nest invader) and a termite species (nest builder). Besides scientifically describing Montezumia termitophila sp. nov. (Vespidae: Eumeninae), named after its association with the termite Constrictotermes cyphergaster (Silvestri, 1901) (Termitidae: Nasutitermitinae), we provide preliminary information about the new species'' bionomics by including (a) a hypothetical life cycle based on the evidence we collected and (b) a footage showing the first interaction between a recently ecloded wasp and a group of termites. In doing so, we attempt to provoke relevant discussions in the field and, perhaps, motivate further studies with the group. Finally, we describe a solution to efficiently detect and sample termitophilous species from termite nests, an intrinsic yet challenging task of any studies dealing with such a cryptic biological system.     

Model of burrow selection predicts pattern of burrow switching by Leach's Storm‐Petrels

Patterns of nest site selection exhibited at the scale of a population should result from initial preferences of individuals occupying nest sites as well as preferences exhibited by individuals moving between nest sites. We tested whether nest‐site preferences measured at the population scale were predictive of patterns of burrow switching by Leach's Storm‐Petrels (Oceanodroma leucorhoa), a long‐lived seabird that nests in underground burrows. Breeding pairs generally choose from the pool of available existing burrows rather than constructing new burrows, and a portion of the burrows in a colony remains unused in any breeding season. We quantified burrow preference at a colony on Kent Island, New Brunswick, over four breeding seasons. We used a classification and regression tree analysis to build a predictive model of nest‐site selection. Preferentially occupied burrows were drier, longer, had larger nest chambers, and were in areas of higher burrow density. To measure preferences during burrow switching, we tracked individuals that switched burrows, comparing characteristics of the burrows in which these birds were originally found to those they inhabited at the end of the study period. Characteristics preferred by switching individuals were a subset of those observed at the scale of the population; individuals moved to burrows that were drier, longer, and had larger nest chambers. Our results show how preferences of individuals that move between nest sites contribute to nest site preferences exhibited at the population scales commonly tested.     

Predatory behaviour in the ant-like wasp Methocha stygia (Say) (Hymenoptera: Tiphiidae)

An examination of prey-orienting behaviour of Methocha stygia has demonstrated that adult females regularly transport prey (Cicindela larvae) when they are removed from their burrows. On a single occasion a wasp was also observed to utilize a naturally occurring depression in the soil as a nest site, instead of depending on the prey's own burrow. This flexibility in response might be a carryover of the behaviour that surely existed in the ancestors of the methochine wasps, insects which were close to if not identical with the ancestors of the ants. When Methocha females were crowded together with prey in the laboratory, frequent avoidance and aggressive behaviours were noted, but no sign of any form of co-operation.     

The nest structure in four wasp species of the genus Euodynerus Dalla Torre (Hymenoptera, Vespidae: Eumeninae)

A comparative analysis of the main parameters of the nest structure and composition in Euodynerus quadrifasciatus, Eu. dantici, Eu. disconotatus, and Eu. velutinus in the Crimea is given. Nests of all the studied species were obtained from trap-nests made of reed stems; the nests of Eu. dantici and Eu. disconotatus were additionally obtained from the abandoned cells of the nests of Sceliphron destillatorium. The nest of Eu. quadrifasciatus consists of a consecutive row of cells, each cell having its own bottom and lid with empty space between them; the nests of three other species consist of an uninterrupted row of cells without spaces, so that the cell bottoms act as partitions. The data on the diameter and length of nest cavities occupied by the studied species, the number of cells in nests, the sex ratio and the length of the cells with prospective females and males are reported. The correlations between the length of the cells and the diameter of the occupied cavities and between the length of the rear empty nest space and vestibule and the length of the occupied nest cavity are analyzed. The structure of cocoons and final nest plugs are described. The difference in the evolution of nest building instincts in members of the subgenera Pareuodynerus and Euodynerus s. str. and the role of adaptation to nest tenantry in the evolution of nest building instincts of Eu. dantici and Eu. disconotatus are discussed.     

Description of the nursery burrow of the Mexican cottontail rabbit Sylvilagus cunicularius under seminatural conditions

The rabbit Sylvilagus cunicularius is endemic to Mexico and is one of the largest, most widespread, but little studied of the country’s 10 rabbit species. As part of a project investigating its reproductive biology, we describe here for the first time the nursery burrow, vital for the survival of the altricial young. During the breeding seasons of 2008–2012, we collected data from 25 nursery burrows and 22 nests constructed by eight females (three wild caught and five captive bred) kept in enclosures within their natural habitat in the Malinche National Park in the central Mexican state of Tlaxcala. Although not a burrow-living species, several days before parturition, females dug a nursery burrow in which they constructed a nest. These burrows were short, shallow tunnels with a median length of 23 cm, typically located beneath grass tussocks or shrubs, and ending in a nest chamber a median 17 cm beneath the surface. Nests consisted of dry grass, fragments of woody plants, pine needles, and alfalfa hay and oat straw provided as supplementary food, fur pulled from the mother’s body, and her fecal pellets. Females nursed their young at the burrow entrance, and until the young were approximately 12 days old, they closed the entrance after each visit in such a way as to make it very difficult for humans to locate. Surprisingly, these nursery burrows were more similar to those of the European rabbit Oryctolagus cuniculus and the pygmy rabbit Brachylagus idahoensis than to other Sylvilagus species studied to date. As almost 50 % of burrows did not result in emergent young, present work is directed to determining what characterizes successful burrows.     

Effects of Prior Residence and Previous Cohabitation on the Polistes dominulus Christ Dominance Hierarchy

We investigated the effects of prior residence and previous cohabitation on the hierarchical relationships established between two wasps which were placed together in hitherto unknown surroundings. When two wasps which were both previously of alpha rank are brought together on the nest already occupied by one of them, the prior resident is likely to become the alpha individual in the newly established hierarchy. Prior residence is not a decisive factor however when two beta-ranked wasps come together. When two wasps which previously belonged to the same social hierarchy were separated for one week, during which time they both became alpha individuals before being reunited, they tended to revert to their original status. The low intensity level of their reactions suggests here that a persistent mnesic trace may have led them to adopt their previous respective attitudes.     

Why Wasp Foundresses Change Nests: Relatedness,Dominance, and Nest Quality

The costs and benefits of different social options are best understood when individuals can be followed as they make different choices, something that can be difficult in social insects. In this detailed study, we follow overwintered females of the social wasp Polistes carolina through different nesting strategies in a stratified habitat where nest site quality varies with proximity to a foraging area, and genetic relatedness among females is known. Females may initiate nests, join nests temporarily or permanently, or abandon nests. Females can become helpers or egglayers, effectively workers or queens. What they actually do can be predicted by a combination of ecological and relatedness factors. Advantages through increased lifetime success of individuals and nests drives foundresses of the social wasp Polistes from solitary to social nest founding. We studied reproductive options of spring foundresses of P. carolina by monitoring individually-marked wasps and assessing reproductive success of each foundress by using DNA microsatellites. We examined what behavioral decisions foundresses make after relaxing a strong ecological constraint, shortage of nesting sites. We also look at the reproductive consequences of different behaviors. As in other Polistes, the most successful strategy for a foundress was to initiate a nest as early as possible and then accept others as subordinates. A common feature for many P. carolina foundresses was, however, that they reassessed their reproductive options by actively monitoring other nests at the field site and sometimes moving permanently to new nests should that offer better (inclusive) fitness prospects compared to their original nests. A clear motivation for moving to new nests was high genetic relatedness; by the end of the foundress period all females were on nests with full sisters.     

Effect of soil hardness on aggression in the solitary wasp Mellinus arvensis

1. Two alternative nesting strategies are exhibited by soil‐nesting Mellinus arvensis females, digging a new nest (diggers) and searching for an old unoccupied burrow (searchers). Wasps appear unable to distinguish between occupied and unoccupied nests, and aggressive interactions between searchers and nest owners at nest entrances are frequent. 2. In aggressive encounters, there is an advantage in size and residency status. 3. The costs associated with the two nesting strategies vary across geographically separated populations: nest digging incurs costs in terms of time, and these vary according to the hardness of the soil substrate; nest searching is variably costly in terms of risk of injury in aggressive encounters with nest‐owning females. 4. Individual female wasps can switch between nesting strategies, and thus soil hardness, by affecting the cost of nest construction, affects the relative frequencies of the two nesting strategies within a population, favouring an increase in the searching strategy. This, in turn, affects the frequency and intensity of aggression between females at a nesting aggregation. 5. Female body size is correlated with soil hardness. As aggressive encounters are more frequent in sites with hard soil substrates, there is increased selective advantage in having large body size at these sites. 6. Body size is determined primarily by the availability of food resources during larval development, which is, to a degree, a function of the size of the adult female. There is a trade‐off between provisioning a few cells with many provisions in each, leading to the development of few but large adults, as opposed to many cells with few provisions, leading to many small offspring. The relative advantage of these two provisioning strategies is, at least in part, a function of the hardness of the soil substrate.     

Interactions between the Social Digger Wasp, <Emphasis Type="Italic">Cerceris rubida</Emphasis>, and Its Brood Parasitic Flies at a Mediterranean Nest Aggregation

The fitness consequence of many behaviours of the small digger wasp, Cerceris rubida (Hymenoptera: Crabronidae), the only European species of its genus in which females share nests, are still unknown. Here, I present novel data on the nesting patterns and nest parasites of an Italian population of this wasp, with emphasis on which behavioural strategies may have evolved to reduce brood parasitism. Nests were established mainly in horizontal surfaces with scarce vegetation and hard soil, resulting in spatially clumped nests; the extent of nest aggregation increased over a 6-year period. Wasp brood cells are attacked by the miltogrammine fly Pterella grisea (Diptera: Sarcophagidae), which waits for nest-returning wasps on perching sites and then follows them in flight (satellite flight), eventually landing on the nest entrance and larvipositing without entering further in the tunnel. This technique seems to be adaptive for the parasitic flies, which would be rejected from nests by the guarding wasps if attempting to enter. The daily activity of the flies closely matched the host wasp’s provisioning activity, but C. rubida females were able to partially confound the tracking flies by performing evasive manoeuvres while returning to the nest. Patches with higher nest density and nests with more resident females did suffer more fly landings on nest entrances (a prerequisite for larviposition). These trends, however, disappeared on a per nest basis and on a per wasp provisioning flight basis, respectively. Across two years, only 6% of brood cells were parasitized, a picture similar to what observed for miltogrammine flies at nest aggregations of other Cerceris spp., and new data are necessary to test if there is a benefit of either nest density or nest sharing against P. grisea parasitism.     

Pupal experience and nestmate recognition in <Emphasis Type="Italic">Polistes dominula</Emphasis> wasps

Social insects can discriminate between nestmates and aliens by comparing the chemical phenotype of an individual with the neural representation of their own colony odor (template). For social paper wasps of the genus Polistes, a general recognition model has been proposed and tested on few North American species: wasps learn colonial recognition cues from the nest paper during the first hours after emergence as adults. However, a recent study revealed that workers of Polistes dominula do not necessarily use the nest paper for early post-emergence cue-learning, suggesting that cues used for the formation of the referent template in this species could be learned at different life stages. Pre-natal learning is a widespread phenomenon in animals and it can shape various behaviors in adults. Here, we investigated whether pre-imaginal learning affects later nestmate recognition in P. dominula wasps. We reared worker pupae in artificial conditions to test whether the absence of nest material, or the exposure to nest material taken from a foreign conspecific colony, during pupal development would alter the nestmate recognition ability in adult life. Our results show that wasps maintain their correct recognition ability regardless of the treatment, suggesting that wasps do not form their referent template during the pupal stage from the nest paper. Alternative hypotheses for template formation timing and source of recognition cues are discussed. Moreover, we investigated whether young wasps already possess, on their own body, reliable chemical cues to form a recognition template by self-referent phenotype matching.     

Social parasitism of <Emphasis Type="Italic">Polistes dominulus</Emphasis> by <Emphasis Type="Italic">Polistes nimphus</Emphasis> (Hymenoptera,Vespidae)

Summary Interspecific facultative social parasitism is well known in ants and in bumble-bees, but it is rarer in wasps. This form of parasitism is traditionally considered to be an intermediate stage in the evolution of obligate interspecific parasitism, where the parasites are no longer able to nest alone. We report field and experimental observations of a newly discovered facultative parasitic relationship between two closely related free-living Polistes species: P. nimphus and P. dominulus. P. nimphus foundresses sometimes usurp the nests of the larger P. dominulus before worker emergence. The invading queen takes over the nest with abundant abdomen stroking on the nest surface and is accepted by workers if they emerge 6 or more days after usurpation. Morphometric comparisons show that the usurper species, though smaller than its victims, has morphological adaptations consisting of larger heads, mandibles and front femora relative to their body size that may give it an advantage during nest invasion. This strategy is likely to be taken only after the foundress loses her original nest because invading P. nimphus queens have lower reproductive success than they would have had on their own nest. Overall, we found that P. nimphus usurpers use strategies of invasion similar to those of two obligate parasites, suggesting that this may be an example of one of the pathways by which social parasitism evolved.Received 4 April 2003; revised 8 August 2003; accepted 14 September 2003.     

A mimetic nesting association between a timid social wasp and an aggressive arboreal ant

In French Guiana, the arboreal nests of the swarm-founding social wasp Protopolybia emortualis (Polistinae) are generally found near those of the arboreal dolichoderine ant Dolichoderus bidens. These wasp nests are typically protected by an envelope, which in turn is covered by an additional carton ‘shelter’ with structure resembling the D. bidens nests. A few wasps constantly guard their nest to keep D. bidens workers from approaching. When alarmed by a strong disturbance, the ants invade the host tree foliage whereas the wasps retreat into their nest. Notably, there is no chemical convergence in the cuticular profiles of the wasps and ants sharing a tree. The aggressiveness of D. bidens likely protects the wasps from army ant raids, but the ants do not benefit from the presence of the wasps; therefore, this relationship corresponds to a kind of commensalism.     

Burrowing owls and burrowing mammals: are ecosystem engineers interchangeable as facilitators?

Terrestrial vertebrates exhibit dynamic, positive interactions that form and dissolve under different circumstances, usually with multiple species as participants. Ecosystem engineers are important facilitators of other species because they cause physical changes in the environment that alter resource availability. Although a species can be associated with more than one partner, facilitators may not be interchangeable if they differ in abundance, behavioral characteristics, or interactions with other factors in ways that condition the outcome of the association. We examined interactions between burrowing owls (Athene cunicularia) and two burrowing mammals, hairy armadillos (Chaetophractus villosus) and plains vizcachas (Lagostomus maximus), and determined whether these ecosystem engineers are interchangeable for owls. We examined reproductive success for owls nesting in these mammal burrows, constructed a logistic regression model to identify habitat characteristics associated with owl nests, and examined the engineering activities of the mammals. Data on reproduction and habitat indicate that armadillos and vizcachas are not interchangeable for owls. Thirty-five percent of the nests in vizcacha burrows produced fledglings; no fledglings were produced from nests outside vizcachas colonies, even though owls nest successfully in armadillo burrows in other parts of Argentina. Vizcachas facilitate burrowing owls by construction of burrows and by producing open understory vegetation through herbivory. In contrast, armadillos do not alter vegetation, and their burrows are suitable for nest sites only when they occur in recently burned areas or areas maintained by anthropogenic disturbance. Our habitat model also suggests that fire plays a key role in maintaining owl populations because fire is the only natural process that reduces shrubs to the level required by owls. Current management practices of eradication of vizcachas and fire suppression in shrublands could have strong negative consequences for burrowing owls.     

How to escape from the host nest: Imperfect chemical mimicry in eucharitid parasitoids and exploitation of the ants’ hygienic behavior

Communication in ants is based to a great extent on chemical compounds. Recognition of intruders is primarily based on cuticular hydrocarbon (CHC) profile matching but is prone to being cheated. Eucharitid wasps are specific parasitoids of the brood of ants; the immature stages are either well integrated within the colony or are protected within the host cocoons, whereas adult wasps at emergence must leave their host nest to reproduce and need to circumvent the ant recognition system to escape unscathed. The behavioral interactions between eucharitid wasps and workers of their host, the Neotropical ant Ectatomma tuberculatum, are characterized. In experimental bioassays, newly emerged parasitoids were not violently aggressed. They remained still and were grabbed by ants upon contact and transported outside the nest; host workers were even observed struggling to reject them. Parasitoids were removed from the nest within five minutes, and most were unharmed, although two wasps (out of 30) were killed during the interaction with the ants. We analyzed the CHCs of the ant and its two parasitoids, Dilocantha lachaudii and Isomerala coronata, and found that although wasps shared all of their compounds with the ants, each wasp species had typical blends and hydrocarbon abundance was also species specific. Furthermore, the wasps had relatively few CHCs compared to E. tuberculatum (22–44% of the host components), and these were present in low amounts. Wasps, only partially mimicking the host CHC profile, were immediately recognized as alien and actively removed from the nest by the ants. Hexane-washed wasps were also transported to the refuse piles, but only after being thoroughly inspected and after most of the workers had initially ignored them. Being recognized as intruder may be to the parasitoids’ advantage, allowing them to quickly leave the natal nest, and therefore enhancing the fitness of these very short lived parasitoids. We suggest that eucharitids take advantage of the hygienic behavior of ants to quickly escape from their host nests.     

Testing hypotheses about the function of repeated nest abandonment as a life history strategy in a passerine bird

Nest structures are essential for successful reproduction in most bird species. Nest construction costs time and energy, and most bird species typically build one nest per breeding attempt. Some species, however, build more than one nest, and the reason for this behaviour is often unclear. In the Grey Fantail Rhipidura albiscapa, nest abandonment before egg‐laying is very common. Fantails will build up to seven nests within a breeding season, and pairs abandon up to 71% of their nests before egg‐laying. We describe multiple nest‐building behaviour in the Grey Fantail and test four hypotheses explaining nest abandonment in this species: cryptic depredation, destruction of nests during storm events, and two anti‐predatory responses (construction of decoy nests to confuse predators, and increasing concealment to ‘hide’ nests more effectively). We found support for only one hypothesis – that abandonment is related to nest concealment. Abandoned nests were significantly less concealed than nests that received eggs. Most abandoned nests were not completely built and none received eggs, thus ruling out cryptic predation. Nests were not more likely to be abandoned following storm events. The decoy nest hypothesis was refuted as abandoned nests were constructed at any point during the breeding season and some nests were dismantled and the material used to build the subsequent nest. Thus, Grey Fantails are flexible about nest‐site locations during the nest‐building phase and readily abandon nest locations if they are found to have deficient security.