Inhibition of Host Queen Reproductive Capacity by the Obligate Social Parasite Polistes atrimandibularis (Hymenoptera,Vespidae)

Polistes atrimandibularis is the obligate and permanent parasite of the social paper wasp Polistes biglumis bimaculatus. This parasite lives together with the host foundress for a considerable period on the invaded nest. Ovarian development was measured in females of the host species (foundresses and, when present, workers) from 18 parasitized and 14 non-parasitized colonies. The reproductive capacity of foundresses from parasitized nests decreased faster than that of foundresses from non-parasitized nests. These results indicate that the presence of the parasite lowers reproductive capacity of the host queen. Simultaneously, the fertility of the host worker is inhibited.     

Variable investments in nests and worker production by the foundresses of Polistes chinensis (Hymenoptera: Vespidae)

The allocation pattern of proteinaceous resources was estimated in preemergence colonies of Polistes chinensis. Foundresses that nested at exposed sites consumed a larger relative amount of proteinaceous resources to produce oral secretion, which is used for construction and maintenance of nests, than those at sheltered sites. Numbers of immatures reared by foundresses were smaller in exposed nests than those in sheltered ones, and further, workers that emerged from exposed nests were significantly smaller in size than those from sheltered ones. Foundresses had to partition available proteinaceous resources not only among the first batch of the brood but also, before that, between brood nourishment and secretion production in response to given environmental conditions. Received: May 17, 1999 / Accepted: September 21, 1999     

Size-dependent reproductive dominance in foundresses of Ropalidia plebeiana, an Australian paper wasp forming nest aggregations (Hymenoptera: Vespidae)

The relationship between reproductive status and body size in foundresses of Ropalidia plebeiana, an Australian endemic paper wasp forming huge aggregations of nests, was examined. Foundresses with developed ovaries (laying foundresses) in multifoundress colonies tended to be larger than foundresses in single‐foundress colonies and foundresses with undeveloped ovaries (non‐laying foundresses). However, the laying foundress was not always the largest of the foundresses in a colony. Body shape in foundresses varied according to simple allometric growth, while foundresses and first brood females diverged in their growth parameters in the preimaginal stage.     

Dynamics of cuticular chemical profiles of Polistes dominulus workers in orphaned nests (Hymenoptera, Vespidae)

We analysed changes in cuticular hydrocarbon signatures of workers in orphaned colonies of the paper wasp Polistes dominulus. In natural conditions, workers and foundresses possess characteristic cuticular signatures, and foundresses are further distinguishable, both behaviourally and chemically, on the basis of their rank in a reproductive dominance hierarchy. In our study, several workers were found to develop their ovaries and produce cuticular signatures resembling those of dominant foundresses, while remaining workers possessed undeveloped ovaries and had cuticular blends characteristic of subordinate foundresses. Workers that did not develop their ovaries had changed epicuticular signatures, demonstrating that the mixture of hydrocarbons of worker individuals is strongly dependent on social role and environment. Our results suggest that the composition of epicuticular lipids is not determined at the pre-imaginal stage, and that physiological pathways leading to cuticular chemical changes are similar in foundresses and workers of P. dominulus.     

Benefits of foundress associations in the paper wasp Polistes dominulus: increased productivity and survival, but no assurance of fitness returns

Successful Polistes dominulus nests can be started by one ormore nest founding queens (foundresses). Consequently, thereis much interest in the specific benefits that induce cooperationamong foundresses. Here, we experimentally demonstrate one majorbenefit of cooperation, namely that multiple foundresses increasecolony productivity. This increase is close to the value predictedby subtracting the productivity of undisturbed single-foundresscolonies from the productivity of undisturbed multiple-foundresscolonies. However, we found no evidence that an associatingfoundress' contribution to colony growth is preserved if shedisappears (assured fitness returns). Our correlational datasuggest that cooperation provides survival benefits, multiple-foundresscolonies are more likely to survive to produce offspring thanare single-foundress colonies, and individual foundresses inmultiple-foundress groups are less likely to disappear beforeworker emergence than foundresses nesting alone. Therefore,association provides substantial productivity and survival benefitsfor cooperating foundresses.     

An experimental analysis of pleometrotic advantage in the desert seed-harvester antMessor pergandei (Hymenoptera; Formicidae)

Summary Starting colonies of the desert seed-harvester antMessor pergandei are clumped in the field and face severe intraspecific competition through brood raiding. Single foundress laboratory colonies ofM. pergandei are more likely to succeed at brood raiding with conspecific colonies if they are given additional workers and mature pupae several days prior to brood raiding. Per foundress fecundity remains constant across laboratory starting colonies established with 1, 3 and 5 foundresses. These results suggest that the selective advantage of cooperative colony foundation (pleometrosis) in this and similar species may derive directly from the ability of multiple foundresses to produce a larger brood raiding force.     

Colony Foundation and Nestmate Recognition in the Social Wasp,Belonogaster petiolata

Emergence from hibernation and synchronized nest foundation by foundresses of B. petiolata in the southern Transvaal, appeared to be stimulated largely by a rise in temperature during early and mid August of each season. Initial foundresses on newly built nests were joined by other foundresses during the first few weeks of the nesting season to form foundress associations. Although females were strongly philopatric and able to discriminate between nestmates (from their natal nests) and non-nestmates, former nestmates did not reassociate to a significant degree on new nests. Thus, associated foundresses were, on average, not closely related. Rather than facilitating the reassociation of former nestmates, the advantage of philopatric behaviour appears to lie in ensuring that foundresses return to an area of relatively high nesting density, where their chances of being involved in multiple-foundress groups (irrespective of intra-colonial relatedness) are high. Non-philopatric females which nest away from localities of high nesting density have a low probability of being involved in associations, and may therefore have to attempt colony foundation alone, with little or no chance of reproducing successfully.     

Reconstruction ofRopalidia fasciata nests by progeny females after a typhoon and its significance in the social evolution of wasps

A strong typhoon, Typhoon 13, which swept through Okinawa on 2 and 3 September 1993, knocked down 57 to 61 of 97Ropalidia fasciata nests. Thirty-five colonies soon reconstructed their nests, and these nests produced 54±46 adults per nest during the remaining two and a half months before winter. The number of females involved in nest reconstruction was 21.3±15.7 per nest. The frequency of foraging activity was significantly higher in nests being reconstructed than in normal nests. As only one out of 205 foundresses marked in spring was found in early September, most cases of nest reconstruction were considered to be made exclusively by females that emerged during the spring and summer of 1993 (progeny females). All of the reconstructed nests but one produced adult females. Many females (31%) collected from the two reconstructed nests were inseminated. As all the reconstructed nests became vacant by early January, indicating completion of the colony cycle, and a large number of nests were established in the spring of 1994, females emerging from reconstructed nests in 1993 probably become foundresses in 1994.Ropalidia fasciata is considered to be, at least partially, bivoltine in Okinawa. The significance of these facts for the evolution of multi-queen social systems in the Polistinae is discussed.     

Rank integration in dominance hierarchies of host colonies by the paper wasp social parasite Polistes sulcifer (Hymenoptera, Vespidae)

In multiple-foundress nests of the wasp Polistes dominulus, dominance hierarchies are established among foundresses, and only the dominant (=alpha) individual lays eggs. The alpha female can be distinguished from subordinate females and workers on the basis of the proportions of some hydrocarbons present on the cuticle, suggesting that chemical signaling of her reproductive status could occur. P. dominulus is also the host species of the obligate social parasite Polistes sulcifer. After aggressively usurping host colonies and behaviorally replacing the host alpha female, parasites are characterized by a change in the proportions of their cuticular hydrocarbons to match that of the host cuticular profile at both species and colony levels. In the current study, we demonstrate that P. sulcifer queens also modify their cuticular hydrocarbon proportions after usurpation to match that of the host alpha female. Parasite females, therefore, acquire the dominant rank in host colonies both reproductively and chemically by mimicking the typical alpha profile of the host. Parasite females were not able to fully inhibit ovary development in host foundresses, and 10 days after usurpation, parasites, alpha and beta foundresses show similar chemical profiles and ovarian development.     

Queen Succession in the Social Wasp,Polistes annularis

Outcomes of conflicts among social animals can strongly affect individual fitness and therefore partly determine how sociality evolves. In the social wasp, Polistes annularis, conflicts over egg laying result in a linear dominance hierarchy discernible from which wasps attack which others. We investigated the structure and maintenance of dominance hierarchies in colonies containing both nest foundresses and workers. We also investigated the outcome of a potential conflict between foundresses and workers over the identity of the female which becomes queen after the original queen disappears. To investigate queen replacement we recorded individuals' behavior before and after removal of the queen from 13 nests. This experiment simulated natural queen disappearance which occurs frequently. All foundresses were ranked over workers; high ranking females were most aggressive and directed most of their attacks to the female directly beneath them in the hierarchy. This hierarchy determined succession to queenship; the beta female became queen within 3 h. Therefore a foundress became the new queen whenever one was present. There was no evidence of conflict between workers and foundresses when a foundress became queen. This chance of becoming queen contributes to the expected fitness of a female that accepts a subordinate role in spring.     

Morpho-physiological variability and differentiation of reproductive roles among foundresses of the primitively eusocial wasp, Belonogaster petiolata (Degeer) (Hymenoptera, Vespidae)

Summary: Pre-nesting foundresses of Belonogaster petiolata (Degeer) displayed a continuous variation in body size and ovarian development, wherein the majority (96%) of females possessed well-developed or developing ovaries. The latter indicates that most foundresses, including those that ultimately become subordinates in multiple-foundress colonies, have the potential to lay eggs when they first initiate or join nests. Relatively small differences in ovarian development between associated females at the start of the nesting season became pronounced over the course of the pre-emergence and early pre-matrifilial period concurrently with the differentiation of their roles as queens or subordinates. In pre-matrifilial colonies, ovarian development of queens was significantly greater than that of subordinates. Dominance rank and ovarian development among subordinates in pre-matrifilial colonies were not correlated, probably due to advanced ovarian regression in these females. The majority (96.5%) of foundresses from three successive nesting seasons were inseminated and would therefore have been capable of laying female-producing (i.e. worker- and queen-destined) eggs. Although queens of B. petiolata were not significantly larger than subordinates, they were the largest females in 41% of colonies. Similarly, #-foundresses were larger on average than %-foundresses. This indicates that body size may contribute to social and reproductive dominance, but is probably of secondary importance compared with hormonal and nutritional factors. These and previously published findings from B. petiolata suggest that the fitness benefits of associating with other foundresses during colony foundation may be largely mutualistic, and favoured by individual selection in addition to kin selection.     

Effect of food availability on larval cannibalism by foundresses of the paper wasp <Emphasis Type="Italic">Polistes chinensis antennalis</Emphasis>

Cannibalism is a behavioral trait seen in a number of species and can be favored when the fitness gain outweighs the cost. In social wasps, field studies have suggested that food limitation causes larval cannibalism as a compensation of a meal for adult wasp and/or earlier production of the first workers, but experimental studies for the effect of food availability on larval cannibalism have been very scarce. Hence we examined whether Polistes chinensis antennalis foundresses exhibit a higher level of larval cannibalization under food-limited conditions than under food-available conditions. Larval cannibalization occurred frequently under both prey- and honey-limited conditions; however, young larvae were more frequently cannibalized than old larvae in the prey-limited colonies, while old larvae were more frequently cannibalized than young larvae in the honey-limited colonies. The number of days between colony initiation and the emergence of the first workers was not significantly different between the prey-limited and prey-available colonies, suggesting that under prey-limited conditions P. chinensis antennalis foundresses tend to cannibalize their young larvae and feed probably the flesh of these cannibalized larvae to old larvae in order to ensure the rapid production of the first workers. On the other hand, the number of days between colony initiation and the emergence of the first workers was longer in the honey-limited colonies than in the honey-available colonies. We propose explanations for the first time for why the foundresses in the honey-limited conditions cannibalized their old larvae more frequently than their young larvae in spite of this resulting in the delayed emergence of the first workers.     

Growth rate and body weight of foundress-reared offspring in a paper wasp, <Emphasis Type="Italic">Polistes chinensis</Emphasis> (Hymenoptera,Vespidae): no influence of food quantity on the first offspring

Summary. Laboratory experiments with Polistes chinensis (Pérez) showed that growth rates and weights of the first-hatched offspring were not different between food-available and food-deficient conditions. In food-deficient colonies, some first-hatched offspring grew quickly, but their dry weights were not different from that of later offspring. The present results suggest that foundresses of P. chinensis may intensively feed some first-hatched larvae to produce the first workers quickly under food-deficient conditions. Since food availability of field foundresses of this species has been estimated as very low, it seems likely that they may produce the first offspring as early as possible by such feeding. On the other hand, heavier offspring were produced when extra food is available, especially in the latter half of the order of emergence. Foundresses of this species may change the amount of prey fed to each larva in response to food availability.     

Geographic Variation in Air Temperature Leads to Intraspecific Variability in the Behavior and Productivity of a Eusocial Insect

In primitively eusocial insects, air temperature is the environmental factor that primarily affects colony cycle. Several studies demonstrated interspecific differences in the adaptation of eusocial insects to local air temperature. Nevertheless, studies on intraspecific adaptations are rare. In this study, we investigate the influence of air temperature on local adaptations in behavior and colony productivity of Polistes biglumis foundresses living in warm and cold temperate zones. We hypothesized that foundresses from warm temperate zones would show a higher activity level compared to those from cold temperate zones before brood emergence, based on differences in air temperature between the two zones. After brood emergence, we expected a reduced foundress activity level in the warm climate zone, due to workers’ help. In contrast, foundresses living in the cold-climate zone, which do not produce workers, were expected to remain active throughout the nesting season. We also hypothesized that colony productivity was higher in warm-climate colonies. As expected, warm-climate foundresses reduced their activity level after brood emergence and, with their relatively large number of workers, continued egg production throughout the nesting season. Further studies are necessary to assess if these intraspecific differences are attributable to phenotypic plasticity or genetic divergence.     

Modes of colony foundation by females of different morphotypes in the paper wasps (Hymenoptera,Vespidae, <Emphasis Type="Italic">Polistes</Emphasis> Latr.)

Paper wasps of the genus Polistes exhibit wide variability both of the color and size of foundresses, and the mode of colony foundation. The colony foundation and social hierarchy were studied in populations of two Palaearctic species, Polistes dominulus (Christ) and P. nimphus (Christ) (April–May 2006, the Crimean Peninsula, Ukraine), and one Neotropical species, P. lanio (F.) (October 2004–January 2005, Trinidad Island). It was shown that foundresses of various color and size morphs tended to found nests in a peculiar way: singly (haplometrosis), by groups (pleometrosis), or occupying several nests simultaneously (polycaly). The relationship between coloration, size, and mode of colony foundation was species-specific. P. dominulus foundresses with a darker clypeus and a paler mesonotum preferred to found nests alone and had a dominant position in pleometrosis. The haplometrotic P. nimphus foundresses more often displayed darker variants of the clypeus and paler variants of the mesonotum than did foundresses from pleometrotic colonies. P. lanio foundresses from pleometrotic colonies differed from those from polycalic colonies in the coloration variability of the scutum, propodeum, and the 2nd metasomal tergite. The dominant and subordinate P. nimphus and P. lanio foundresses differed in the size of head and wings. The possible significance of the subdivision of foundresses into the “generalists” and “specialists” for the variability structuring in the population is considered.     

Colony development and social structure in a subtropical paper wasp,Ropalidia fasciata (F.) (Hymenoptera: Vespidae)

More than 50% of nests of Ropalidia fasciata were founded by association of foundresses (multifemale nests). The multifemale nests were generally initiated earlier and grew faster than the single-female nests. The survival rate of the multifemale nests was significantly higher than that of single-female nests, and the productivity as measured by the number of cells produced per foundress had a peak at a foundress-group size from 6 to 10. The number of marked foundresses which were seen on their original nest decreased as the colony cycle proceeded, but some of them continued to coexist on the original nests after emergency of many female progeny. Except in the case where a large number of foundresses attended a young nest so that some foundresses could not sit on the nest, the dominance interactions among cofoundresses were mild. More than twothirds (71.4%) of nests (including those at the post-emergence stage) had multiple egg-layers. The foundress association in this species is considered to be beneficial for every foundress because it raises ability to avoid predation or to reconstruct their nests when the nests are destroyed by typhoons.     

Water loss in desert ants: caste variation and the effect of cuticle abrasion

Water loss rates (WLRs) varied across castes (workers > alate males > alate females) for desert ants in the genera Aphaenogaster, Messor and Pogonomyrmex. Exposure to soil caused increased WLRs in workers and foundresses (mated, dealate females), apparently because of cuticular abrasion caused by nest excavation. Moreover, field‐collected workers and foundresses from incipient nests (those exposed to soil) had similar WLRs, as did unabraded workers and alate females (those unexposed to soil). These data call into question previous adaptive scenarios for differences in WLRs across ant species and castes. For live alate females, WLRs increased over two stages. The first increase occurred immediately after mating, and the second occurred for foundresses collected 2 days later from incipient nests. By contrast, WLRs of HCN‐killed females were unaffected by mating, but increased significantly for foundresses collected from 2‐day‐old nests.     

Overwintering colonies of German (Vespula germanica) and common wasps (Vespula vulgaris) (Hymenoptera: Vespidae) in New Zealand

Abstract

Nests of both common (Vespula vulgaris) and German wasps (V. germanica) sometimes overwinter in New Zealand. Three overwintering common wasp colonies were found in low-altitude honeydew beech forest; about 2% of the colonies initiated there in 1988 survived the winter. Wasp traffic rates from nests in Nelson city and a nation wide survey of wasp abundance, showed that more German wasp than common wasp workers were on the wing in winter and spring. German wasp colonies in Nelson city were more likely to overwinter than were common wasp colonies. Of the active German wasp colonies recorded in Nelson in January and February 1989, only two (4%) had previously overwintered, but these two nests accounted for 38% of all German wasp workers estimated to leave nests in the area. Had other overwintering colonies not been poisoned, overwintering colonies might have accounted for up to 11 % of nests and produced up to 64% of German wasp workers on the wing in January and February 1989.

Overwintering common wasp colonies did not produce queens or drones in their first year or second spring, but all 10 overwintering German wasp colonies examined produced sexuals at both times. German wasp queens produced in winter and spring may influence the number of colonies successfully initiated and affect the population dynamics of German wasps in New Zealand.     

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.     

Growth-related changes in predation behavior in incipient colonies of the ponerine antEctatomma tuberculatum (Olivier)

Summary We traced the development in the laboratory of 18 young colonies of the arboricolous ponerine antEctatomma tuberculatum. Colony foundation is of the partially-claustral type. During the early stages, when the colony is entirely dependent on the queen's behavior, the growth of the colony in terms of number of workers produced over time was relatively predictable. Afterwards, divergence in colony growth in function of the time increases as fast as the number of workers influences the efficiency of colony provisioning.Comparative analysis indicated clear changes in the predation behavior of foundresses and workers as colonies developed. For any stage of colony growth, all individuals provisioned the nest with dead prey or sugar-rich substances in the same way. However, prey hunting involves two different strategies. Foundresses and nanitic workers (originating from colonies with 9–15 workers) foraged actively, catching prey as the result of random encounters. Post-nanitic foragers (originating from colonies with 20–30 workers) and those from nature colonies developed an ambush strategy. Workers in these colonies gained experience at catching and handling prey during a period when they acted as nest guards, and so tended to be more efficient hunters than poorly experienced foundresses or nanitic foragers. The change in strategy was also positively correlated with an increase in the size of workers as the colony matured. A stable maximum in workers size is apparently reached only after the appearance of efficiently hunting foragers, presumably in numbers sufficient to provide adequate quantity and quality of larval food. Such a correlation between worker size and colony growth, assumed general for all ants, has not been demonstrated for Ponerinae before this work.