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A novel ‘sit and wait’ reproductive strategy in social waSPS
Proceedings of the Royal Society B
Abstract
I present evidence indicating that a subset of spring females in the social wasp Polistes dominulus do not initiate colonies but rather 'sit and wait' to adopt colonies initiated and abandoned by other conspecifics. These results are, to my knowledge, the first to demonstrate conclusively this alternative reproductive strategy in social wasps. Individuals engaging in the sit-and-wait strategy behave selfishly by adopting the most mature nests available; such nests will produce workers sooner than less mature nests and, consequently, are more likely to survive. The sit-and-wait reproductive strategy may safeguard an individual from early-season, foraging-related mortality as well as reduce early-season energy expenditure.
... In collaborations, one female becomes dominant and lays the majority of eggs , which fits with the definition of eusociality. When the brood matures, some of the offspring decide not to mate and become workers, thereby sacrificing their totipotency (Reeve et al. 1998b, Starks 1998. Thus the relationship between the foundress and her workers is obligately eusocial. ...
... Several lines of evidence, however, suggest that there are not pervasive differences in reproductive capabilities of temperate wasps at the nest initiation phase. Large wasps are not better than small ones at building or providing for offspring as single foundresses (Nonacs & Reeve 1995), and subordinates within groups are reproductively capable as they readily lay eggs if opportunities arise (Reeve 1991, Field et al. 1998, Starks 1998; but see Gadagkar 1990Gadagkar , 1996. Therefore if neither reproductive benefits nor ecological and morphological constraints can account for cooperation, there must be another factor involved. ...
... For example, even if subordinates contribute eggs only during the part of the colony life cycle devoted to worker production, it is possible that a large percentage of these offspring will adopt reproductive strategies. These can include ascending to reproductive dominance on their natal nests, usurping weak foundresses on other nests, adopting orphaned nests, initiating their own nests immediately, or entering early hibernation and emerging the following year as foundresses (Nonacs & Reeve 1993, 1995, Gadagkar 1996, Reeve et al. 1998b, Starks 1998. I (unpubl. ...
A social behavior continuum from simple to complex is argued to be a basis for evolutionary categorization of species. I propose a complimentary view that compares similar life history decisions because social complexity varies in many species across their lifetimes. I specifically concentrate on the evolution of reproductive skew in cooperative breeding, which I define relative to the ability of group members to live solitarily or move easily between groups (i.e., facultative versus obligate eusociality). Facultative cooperation can arise through social contracts based either on conventions (arbitrary asymmetries determines status), or transactions (individuals cede benefits for group stability). These mechanisms predict different within-group dynamics. An analysis of transactional models predicts eusocial evolution requires large asymmetries between dominants and subordinates in ability to succeed independently. The only major exception appears to be cooperative colony initiation by polistine wasps. Their behavior, however, may have evolved due to a unique combination of reproductive gains through sex ratio conflicts with workers and factors that select for reproductive plasticity in offspring. Examining eusocial evolution as a specific life history trait also suggests that facultative versus obligate cooperation correlates with assumptions about dominant control over skew within groups. 'Concession' type models tend to predict behavior in facultative situations, while 'Tug-of-war' models do better in obligate situations.
... When the fitness of each tactic is negatively frequency dependent on the other tactic, the population will reach an equilibrium point for the average fitness payoff. (Nonacs & Reeve 1993), lost their colonies due to predation or other forms of damage (Cervo & Dani 1996), or waited to adopt an orphaned nest instead of initiating one (Nonacs & Reeve 1993, Starks 1998, 2001. Within an enclosure, it has been shown that the P. dominulus females who engage in the sit-and-wait reproductive tactic adopt the most mature nests (Starks 1998(Starks , 2001, see also Nonacs & Reeve 1993) and prefer orphaned nests with a large number of fourth and fifth instar larvae. ...
... (Nonacs & Reeve 1993), lost their colonies due to predation or other forms of damage (Cervo & Dani 1996), or waited to adopt an orphaned nest instead of initiating one (Nonacs & Reeve 1993, Starks 1998, 2001. Within an enclosure, it has been shown that the P. dominulus females who engage in the sit-and-wait reproductive tactic adopt the most mature nests (Starks 1998(Starks , 2001, see also Nonacs & Reeve 1993) and prefer orphaned nests with a large number of fourth and fifth instar larvae. Data indicate that adopters are less cooperative than nest initiators, prefer mature nests to nests with a higher likelihood of kinship, and conserve energy during the nest founding period (Starks 2001). ...
... Data indicate that adopters are less cooperative than nest initiators, prefer mature nests to nests with a higher likelihood of kinship, and conserve energy during the nest founding period (Starks 2001). As with cases of usurpation (Klahn 1988), once adoption occurs, adopters destroy the previous foundress' eggs and early instar larvae and replace them with their own eggs; older larvae and pupae are allowed to complete development (Starks 1998). ...
Here we present a novel model for the selective maintenance of alternative phenotypes. Our model is appropriate for systems where the expression of alternative tactics is both condition and frequency dependent. We use Polistes dominulus as our model system, and show how frequencies of solitary nest founding, collaborative nest founding, usurpation of defended nests, and adoption of abandoned nests are predicted to vary with changes in ecological and social conditions. To accomplish this we (1) review commonly used models that explain the selective maintenance of alternative phenotypes, (2) describe some basic life-history characteristics of Polistes wasps, (3) present a novel condition dependent mixed strategy model, (4) use this model to predict frequencies of alternative tactics under conditions of differing survivability, relatedness between co-foundresses, and reproductive skew between co-foundresses, and (5) provide future directions for refining and testing this unifying model.
... All seven species of Polistes reported to exhibit nestmate recognition are temperate species . These species include P. metricus, P. fuscatus , P. exclamans, P. carolina and P. annularis (Gamboa 1996) as well as the more recently studied P. biglumis (Lorenzi et al. 1997) and P. dominulus (Starks et al. 1998). Since most species of Polistes are tropical (Reeve 1991), our knowledge of nestmate recognition in Polistes is limited to a minority subset of the genus. ...
... Female P. fuscatus (Ferguson et al. 1987), P. metricus (Espelie et al. 1990b), Dolichovespula maculata (Ferguson et al. 1987), P. dominulus (Starks et al. 1998, Lorenzi & Caprio 2000, Starks 2003), and P. biglumis (Lorenzi & Caprio 2003) can discriminate their own comb or comb fragment from that of foreign colonies. Pfennig (1990) reported that P. exclamans workers can discriminate between a brood-filled fragment from their own comb and that from another colony although it's not clear whether workers recognized the comb, brood, or both. ...
... Nest adoption may be affected by the presence of brood, and wasps may perceive nests with brood as a more valuable resource than an empty nest. In fact, Starks (1998, 2001) has presented evidence that P. dominulus foundresses preferentially adopt colonies with more mature brood. Nests with brood could provide a food source for adoptees or provide adoptees a worker force. ...
Greenberg's landmark publication (Science 206[1979]: 1095-1097) on kin recognition in sweat bees was followed closely by experimental studies of kin recognition in primitively eusocial paper wasps. These early studies of recognition in social wasps concentrated on documenting nestmate recognition ability, which then stimulated interest in the mechanism subserving recognition ability. For the major portion of my review, I summarize our current understanding of kin, brood, and nest recognition ability in social wasps and its underlying mechanism, relying primarily on paper wasps (Polistes) as a model system. In my discussion of the mechanism of recognition, I review our understanding of the perception, expression, and action components of recognition. I also provide a synopsis of the recent recognition studies of two species of Polistes and their congeneric, obligate social parasites. Finally, I discuss our understanding of the ecology of kin recognition in social wasps and then close my review by contemplating the future directions of kin recognition research.
... Additionally, instead of initiating a new colony, females can usurp a foreign nest to become the primary reproductive or adopt an orphaned nest (Klahn 1988, Starks 1998). In both cases, the usurpers and adopters destroy the eggs and early instar larvae and replace them with their own (Klahn 1988, Starks 2001. ...
... If the female decides to stay in her natal nest, she can pursue two alternative reproductive tactics: compete with the other females to become the primary reproductive or instead remain in the colony as an auxiliary (Röseler 1991). If the female decides to leave, she can initiate construction of a new nest as a solitary foundress, join a foreign colony (Starks 1998, Sumner et al. 2007, adopt an orphaned nest (Starks 2001), or usurp another colony to become the primary reproductive (Clouse 1995, Nonacs andReeve 1995). ...
... Reproductive tactics are also affected by seasonality in temperate zones (Gunnels 2007, Starks 1998, Starks 2001. A study of a temperate population of Mischocyttarus mexicanus revealed that females received different payoffs using alternative reproductive tactics during different seasons Gunnels (2007). ...
Reproductive division of labor is the most distinctive characteristic of the social Hymenoptera; some individuals reproduce and others forego their own reproduction to raise non-descendant offspring. In species where females are reproductively totipotent and lack morphologically distinct castes, there is potential for reproductive conflict because more than one female in a colony may attempt direct reproduction. I focused my dissertation research on a subtropical population of the primitively eusocial paper wasp, Mischocyttarus mexicanus, to investigate the initiation, establishment, and development of the colony before the emergence of adult offspring. Female M. mexicanus exhibit variation in behavior and task performance, and switch between reproductive and non-reproductive roles. These changes in behavior and reproduction may be influenced by social context. In three studies, I investigated the role of social context on reproduction, behavior, and brain structure. In the first study, I tested the role of body size, reproductive potential, and immediate egg-laying potential on the reproductive tactic employed by females. I found that large females either became solitary foundresses or became part of a group-initiated colony. In contrast, small females left their natal colony and pursued joining other colonies. This joiner tactic is unique to this population and has not been observed in temperate zone populations. I also found that subordinate females had the potential to lay eggs if given the opportunity. This suggests an incentive to remain in a colony for future opportunities of direct reproduction. In the second study, I investigated the effect of three variables on non-nestmate acceptance: non-nestmate age, stage of colony development, and non-nestmate aggressive behavior. I demonstrated that non-nestmate acceptance was context-dependent. Both non-nestmate age and stage of colony development had an effect on the proportion of accepted non-nestmates. Although, non-nestmate aggressive behavior did not affect non-nestmate acceptance, it did trigger an aggressive response from colony nestmates. In the third study, I assessed the relationship of Mushroom Bodies (MB) volume, the brain neuropils associated with learning and memory, to environmental conditions and social interactions. I compared MB volume of newly-established colonies initiated by solitary foundresses to groups of foundresses. In addition, I performed laboratory experiments to differentiate between the effect of environmental conditions and social interactions. I found a positive relationship between MB volume and environmental conditions including light intensity and foraging experience. In contrast to previous studies, I found no association between MB volume and social interactions. Ovary development was positively correlated with MB development. This result suggests that although reproductive dominance is established in newly-initiated colonies, social dominance may not yet be established. In summary, my studies found an effect of social context on behavior, adoption of reproductive tactics and brain structure in colonies of M. mexicanus during the offspring pre-emergence phase.
... Females that adopt abandoned nests may have left multiple-foundress associations (Nonacs & Reeve 1993), lost their colonies due to predation or other forms of damage (Cervo & Dani 1996), or waited to adopt an orphaned nest instead of initiating one of their own (Nonacs & Reeve 1993, Starks 1998). Within an enclosure, Starks (1998) showed that the P. dominulus females who engage in the sit-and-wait reproductive tactic preferentially adopt the most mature nests (see also Nonacs & Reeve 1993) and show a preference for orphaned nests with a large number of fourth and fifth instar larvae. ...
... Females that adopt abandoned nests may have left multiple-foundress associations (Nonacs & Reeve 1993), lost their colonies due to predation or other forms of damage (Cervo & Dani 1996), or waited to adopt an orphaned nest instead of initiating one of their own (Nonacs & Reeve 1993, Starks 1998). Within an enclosure, Starks (1998) showed that the P. dominulus females who engage in the sit-and-wait reproductive tactic preferentially adopt the most mature nests (see also Nonacs & Reeve 1993) and show a preference for orphaned nests with a large number of fourth and fifth instar larvae. As with cases of usurpation (Klahn 1988), once adoption had occurred, adopters destroyed the previous foundress' eggs and early instar larvae and replaced them with their own eggs; the older larvae and pupae were allowed to complete development (Starks 1998). ...
... Within an enclosure, Starks (1998) showed that the P. dominulus females who engage in the sit-and-wait reproductive tactic preferentially adopt the most mature nests (see also Nonacs & Reeve 1993) and show a preference for orphaned nests with a large number of fourth and fifth instar larvae. As with cases of usurpation (Klahn 1988), once adoption had occurred, adopters destroyed the previous foundress' eggs and early instar larvae and replaced them with their own eggs; the older larvae and pupae were allowed to complete development (Starks 1998). ...
Polistes dominulus females that adopt nests are less cooperative and may expend less energy than nest founding wasps. In an enclosure, 14 nests were adopted by individuals previously unassociated with any nest. No preference for enclosure or non-enclosure nests was detected, suggesting that adopters do not preferentially secure nests containing non-descendent kin. Instead, adopters - who were significantly less likely cooperate than nest constructing wasps - maximized direct fitness benefits by adopting nests most likely to produce reproductives. Preliminary data comparing body weights of adopters to nest constructors suggests that, relative to nest constructors, adopters gain weight during the nest founding period. Combined, these results indicate that adopters are less cooperative than nest initiators, prefer mature nests to nests with a higher likelihood of kinship, and may conserve energy during the nest founding period. Several additional reproductive tactics were observed and a preliminary flow diagram of these options is provided.
... This means that, at least in some species, even workers have the option of leaving the nest, mating and nesting solitarily. This seldom happens in most species (but see [17][18][19]). In particular it is unlikely in P. carolina, since they are unique among Texas Polistes in not producing a few males in the first brood. ...
... [22] Foundresses can also take advantage of each other's nest-founding efforts by usurping nests initiated and built by others, by taking them over (usurpation), as in P. dominula [21] and P. biglumis [23], [24], or by adopting recently abandoned nests, as in P. dominula. [18], [19], [21], [25] Breeder composition is also unstable in another group of primitively eusocial wasps, the Stenogastrinae. For instance, a considerable proportion of Liostenogaster avolineata females are ''floaters'', who leave their natal nests and join or adopt other nests. ...
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.
... The third purpose is to alleviate the cost to the fi rst females of constructing new nests. The cost of new nest construction is high for the wasps (Maschwitz et al., 1990; Yamane et al., 1996; Kudô et al., 1996; 1998). Our procedures provide the wasps with an opportunity to use the comb without incurring any new-nest related construction costs. ...
... The last possibility is the sit-and-wait reproductive strategy of the fi rst females. A subset of spring females do not initiate colonies but rather sit-and-wait to adopt the colonies initiated and abandoned by other conspecifi cs (Starks, 1998). Under this strategy, the individuals may not be subject to forage-related mortality and/or energy expenditure in early phase of new nest construction. ...
Although nests are central to colonial life in social insects, nests are sometimes damaged by predators or natural disasters.
After nest destruction, individuals usually construct new nests. In this case, a sophisticated mechanism like the scent trail
pheromone used in large insect colonies that recruit individuals to new nest sites would be important for the maintenance
of eusociality. In independent-founding Polistes wasps, it is well known that queens enforce workers physiologically on the natal nests even if evidence of trail pheromone
use has not been exhibited. We investigated the effect of the queen on an alternative strategy for the maintenance of eusociality
by first females after nest destruction in the primitively eusocial wasp Polistes chinensis. We predicted that the first females in queen-absent colonies have various behavioral options after nest destruction. Even
if the females construct new nests cooperatively with other individuals, the new nest construction should be conducted more
smoothly in queen-present colonies because the queens regulate the behavior of wasps. We made wasps construct new nests by
removing the entire brood from existing nests. The presence of the queen did not cause variation in the alternative strategy
of the first females, as the first females (workers) usually constructed new nests cooperatively irrespective of the queen-presence.
Thus, the workers in the queenpresent colonies affiliated to the new nest construction more smoothly and constructed new nests
more efficiently than workers in the queen-absent colonies. Our results suggest that the presence of the queen is important
for maintaining eusociality in primitively eusocial wasps after nest destruction.
... In the colony-founding phase of Polistes paper wasp societies, mated females called foundresses have several nesting options. Traditionally, these included the three options of building nests solitarily, joining cooperative nesting groups and usurping the dominant position on an active nest (reviewed in Reeve 1991), which were later expanded to include the option of waiting to adopt an orphaned nest (Nonacs & Reeve 1993;Starks 1998). Before emergence of the first offspring cohort, foundresses perform all colony tasks, including foraging for nest materials and hunting for prey to feed the developing brood. ...
... Queller et al. 2000;Shreeves et al. 2003), as well as in the introduced North American range (e.g. Nonacs & Reeve 1993;Starks 1998Starks , 2001Tibbetts & Reeve 2003). showed that population genetic diversity of introduced P. dominulus in the northeastern U.S. is comparable to diversity in the native range, and therefore studies of these populations are not confounded by genetic bottleneck effects often associated with introduced species. ...
Female Polistes paper wasps can initiate colonies either solitarily or in cooperative groups. Reproduction is often distributed unequally in groups, even to the point of complete monopolization of breeding by the dominant group member. Transactional models of reproductive skew predict the degree of reproductive partitioning, assuming that the dominant controls group membership and will yield a proportion of reproduction to a subordinate as an incentive to stay peacefully in the group. Using a combination of demographic, genetic and morphological data from a population of P. dominulus, we test predictions of ‘classical’ two-person skew models as well as more complex ‘N-person’ models. This is the most comprehensive study of skew in this species to date, and the results generally do not support transactional models. We found no relationship between skew and relatedness for dyads, and complete skew was observed in unrelated groups despite the prediction for this population that such groups should not occur. In contrast to N-person model predictions, group size tended to increase with relatedness. Although we did find the predicted positive correlation between group size and skew for groups of nonrelatives, this relationship was weak. The zone of conflict between the predicted minimum and maximum staying incentives often spans the entire possible range of reproductive skew, suggesting that a ‘tug-of-war’ scenario may be more appropriate than a transactional framework for understanding within-colony dynamics. Overall, our results demonstrate that transactional skew models have little predictive power and are therefore unlikely to yield further insight into Polistes wasp societies.
... Also, the success of individual wasps does not appear to be strongly physiologically constrained. Large wasps are not better than small ones at building or providing for offspring as single foundresses (Nonacs and Reeve 1995), and previously nonreproductive individuals readily lay eggs if suitable opportunities arise (Reeve 1991; Shakarad and Gadagkar 1997; Field et al. 1998; Starks 1998 Starks , 2001 Reeve et al. 2000). In the context of skew models, therefore, it is most likely that at the initiation of x ≈ 1 cooperation between wasp foundresses. ...
... Recent evidence suggests a significant fraction of the first wasps to mature may rapidly abandon their natal nest (Reeve et al. 1998a). Across several species, such " early females " have been found to usurp weak foundresses on other nests, to adopt orphaned nests, to initiate their own nests immediately, or to enter early hibernation and emerge the following year as foundresses ( Reeve 1993, 1995; Gadagkar 1996; Reeve et al. 1998a; Starks 1998 Starks , 2001 ). Reproductive plasticity potentially significantly contributes to the direct fitness of subordinates. ...
Cooperative breeding often involves reproductive dominance hierarchies. Such hierarchies have been proposed to form and to be maintained through an equitable skew in reproduction for both dominants and subordinates. The general form of skew models also predicts that cooperation can be stable only if cooperation greatly increases group reproductive success or subordinates are greatly constrained in their reproductive prospects relative to dominants. Neither, however, seems to be generally present in the colony initiation phase of temperate polistine wasps, although the behaviors of individuals within such groups are often consistent with skew model predictions. This apparent contradiction can be resolved in the context of a special case of the skew models that incorporate mother-offspring conflicts over sex ratios. Data suggest that all the needed preconditions are present for cooperating foundresses to gain an added benefit through producing male-biased investment ratios. Therefore, the special case model predicts that cooperation can evolve in Hymenoptera with both the observed high skews and reduced per capita group productivity. Further predictions of the special case model (e.g., mixed populations of single and multifoundresses) are also supported. Because the special case model is applicable only to haplodiploids, this may explain why cooperation in vertebrates rarely occurs without significant ecological or physiological constraints. Finally, comparisons to other social Hymenoptera taxa suggest that factors stabilizing cooperation between colony-initiating females may simultaneously constrain the evolution of morphologically specialized worker castes.
... However, successful and productive rearing in the lab has proven challenging. Although Polistes have been studied effectively in the lab throughout their life cycle, establishing multiple generation lab lines has been a major hurdle for polistine biologists (Gibo, 1977;Post and Jeanne, 1982;Starks, 1998;Kudô, 2003;Jandt, et al., 2015). Along with replicating overwintering conditions, stimulating nest-founding, and promoting colony growth, successfully inducing mating in the lab is a major challenge for lab-rearing Polistes (personal communication, several social wasp biologists). ...
Hormones are often major regulators of complex behaviors, such as mating and reproduction. In insects, juvenile hormone (JH) is integral to many components of reproductive physiology and behavior, but its role in female sexual receptivity is not well understood. To investigate the influence of JH on receptivity, we utilized the social wasp Polistes fuscatus. In Polistes, mating behavior is temporally separated from other components of reproduction, which allows for examination of the physiology and behavior of mating, disentangled from fertilization and egg-laying. We reared virgin gynes (reproductive females) in the lab and divided them into four groups, in which gynes received multiple topical treatments of either 20μg, 10μg, 5μg, or 0μg of the JH analog methoprene. Gynes were then placed in petri dishes with 2 unrelated males and we recorded attempted and successful mating. Additionally, we measured gyne ovarian development and survival in each group. We found that methoprene increased both sexual receptivity and ovarian development, but was associated with a decrease in long-term survival. Receptivity increased linearly as methoprene treatment increased, but the effect of methoprene on ovarian development was independent of dose. These results demonstrate the importance of JH in sexual receptivity and mating behavior. We argue that the relatively understudied Polistes gyne has potential as a model for mating and reproduction, and for the internal and external regulation of this complex behavior.
... We used these values to calculate maturity score on the nests. Maturity scores are calculated based on the time needed for eggs to develop into larvae and pupae (Strassmann and Orgren 1983;Starks 1998). A maturity score of 1 means that all cells in the nest are occupied by eggs, maturity scores lower than 1 indicate empty nest cells, and maturity scores higher than 1 indicate more development into larvae and pupae. ...
Two major challenges in studying the impacts of exotic invasive species on native species are identifying mechanisms of displacement and replacement and the lack of long-term population studies in these systems. A solution for the first is to study invasive and native congeners that occupy the same niche. A solution for the second is to study many populations for one year instead of one population for many years. We studied the invasion biology of the invasive European paper wasp Polistes dominula and its native congener the Northern paper wasp P. fuscatus, two species which compete for similar resources. We tracked the demography of the two wasps at sites in the northeastern United States. We found that the survival of P. dominula to the reproductive period in August was three times that of P. fuscatus, across all sites. The reproductive output of P. fuscatus declined in direct proportion to the percentage of P. dominula nests at the site. P. fuscatus nests at uninvaded sites had three times the nest cells of those at the most invaded sites. These findings suggest a positive feedback cycle in the establishment of P. dominula, in which the invasive wasp drives population declines in the native that in turn allow P. dominula to further establish. This system provides an example of a possible extinction vortex caused by competitive exclusion of a species by its invasive congener.
... This 'waiting strategy' of parasitized wasps (possibly to infect larvae) agrees with the behaviour of social parasites of paper wasps, which typically leave hibernation sites later than their hosts (CERVO, 2006). Anyway, this 'sit and wait' behaviour is not infrequent amongst unparasitized wasps that delay nesting (STARKS, 1998). During late winter collections for hibernant wasps, we recorded small aggregations of stylopized and healthy wasps under tiles or other shelters on the top of roofs, whereas the majority of gynes were spaced in the whole roof or involved in nest foundation (L.B., pers obs.). ...
Beani L., Massolo A. – Polistes dominulus wasps (Hymenoptera Vespidae), if parasitized by Xenos vesparum (Strepsiptera
Stylopidae), wander among nests during the pre-emergence phase.
This study is focused on the spatial behaviour of overwintered Polistes dominulus wasps, either unparasitized or
parasitized by Xenos vesparum (Strepsiptera). The neotenic female endoparasites protrude their cephalothorax from
the host abdomen and, after winter diapause, hundreds of 1st instar larvae, the infective free-living stage, emerge alive
and move from the brood canal of the cephalothorax to the substrate. We carried out spring transects along artificial
hibernation/nesting sites showing a high site-attachment of healthy wasps before and mainly after nest foundation,
whereas parasitized ones moved from one colony to another just when wasp larvae, the target of infection, are present
in nests. These data support the hypothesis of a direct release of Xenos larvae on/close to nests although phoresy,
assumed as the usual infection mechanism for Strepsipterans, is also possible.
KEY WORDS: Strepsiptera, paper wasps, spatial behaviour, phoretic infection, nest infection.
... During the colony founding phase, Polistes paper wasps exhibit dif ferent reproductive tactics, including: the establishment of new nests by a sole female or a group of females, called respectively solitar y and associative foundation (Pardi 1948, West-Eberhard 1969, Reeve 1991; nest usurpation, where intruders aggressively expels the original adults from its own nest (Prezoto & Nascimento 1999, Brito et al. 2010; adoption of orphan nests, in which intruders adopt a nest with immature forms, but no adults (Nonacs & Reeve 1993, Hunt 2009); and use of empty nests when nest has no host immature or adults (Starks 1998, Prezoto et al 2002. ...
Successful heterospecifi c use of abandoned nests has been reported in birds. Although the same behavior has been observed in wasps, the success of such tactic has not been demonstrated. We described two cases in which the social wasp Polistes versicolor successfully reared its brood in empty nests of the social wasps Mischocyttarus drewseni and Mischocyttarus cassununga (Hymenoptera: Vespidae). We showed that this is a rare but a viable reproductive tactic for both solitary and associative foundress. Unlike birds, which use heterspecifi c nests very similar to their own, wasps are able to use heterspecifi c nests that do differ from their own.
... During the colony founding phase, Polistes paper wasps exhibit dif ferent reproductive tactics, including: the establishment of new nests by a sole female or a group of females, called respectively solitar y and associative foundation (Pardi 1948, West-Eberhard 1969, Reeve 1991; nest usurpation, where intruders aggressively expels the original adults from its own nest (Prezoto & Nascimento 1999, Brito et al. 2010; adoption of orphan nests, in which intruders adopt a nest with immature forms, but no adults (Nonacs & Reeve 1993, Hunt 2009); and use of empty nests when nest has no host immature or adults (Starks 1998, Prezoto et al 2002. ...
Successful heterospecific use of abandoned nests has been reported in birds. Although the same behavior has been observed in wasps, the success of such tactic has not been demonstrated. We described two cases in which the social wasp Polistes versicolor successfully reared its brood in empty nests of the social wasps Mischocyttarus drewseni and Mischocyttarus cassununga (Hymenoptera: Vespidae). We showed that this is a rare but a viable reproductive tactic for both solitary and associative foundress. Unlike birds, which use heterspecific nests very similar to their own, wasps are able to use heterspecific nests that do differ from their own.
... The first is early in the colony cycle in the ''founding phase,'' among females that initiate a nest together, called foundresses (mated females that have dispersed from their natal colonies to establish new colonies). Foundresses use multiple strategies to establish a colony: (1) initiate nest building alone, (2) cooperate with other foundresses throughout the founding stage, (3) 'sit-and-wait' until another foundress abandons her nest and adopt it (Starks, 1998;Starks, 2001;Liebert et al., 2005) or 4) challenge the sitting foundress in an attempt to usurp the nest (Nonacs and Reeve, 1995). Foundresses rear a first generation of female offspring, which typically become workers (unmated females with limited reproductive capacity that perform numerous colony maintenance behaviors), at which time the colony enters the ''worker phase''. ...
Polistes are an ideal system to study ultimate and proximate questions of dominance, and to test theo-retical predictions about social evolution. The behaviors typically associated with dominance in Polistes are similar to those observed in many vertebrate societies. Here, we review recent ethological, mechanistic, and evolutionary studies on how social dominance hierarchies are established and maintained in Polistes spp. From the ultimate per-spective, we address individual and group benefits of hierarchy formation, as well as issues such as reproductive skew, queen-worker conflict, and costs of challenging the dominant. From the proximate perspective, we review social, physical, and physiological factors influencing hierarchy formation, including co-foundress interactions, age structure, body size, endocrine system, and chemical and visual signals. We also discuss the extensive inter-and intra-specific variation of Polistes in the formation and maintenance of hierarchies, as well as levels of within-colony aggression. We conclude the review by highlighting the utility of this variation for comparative studies and the immense potential of the genus Polistes to address funda-mental and unanswered questions about the evolution and maintenance of dominance behavior in animals.
... If they act as infection vectors to the next generation of the host, waiting for the full development of triungulins and mature Polistes nests in sheltered inactive groups could be advantageous for the parasite. An analogous 'sit and wait strategy' has been described for colony usurpation by conspecifics (Starks 1998), as well as by social parasites (Cervo & Dani 1996). An increased diapause period is in agreement with the time arms race between the parasite and its host during infection. ...
The macroparasite Xenos vesparum affects both the behaviour and the physical traits of its host, the social wasp Polistes dominulus. Female wasps, if parasitized, do not perform any social tasks and desert the colony to gather at specific sites, where the parasite mates; at the end of summer they form prehibernating clusters joined by healthy future queens to overwinter. Parasitized wasps become highly gregarious. In April, healthy wasps leave the aggregations to found new colonies, while parasitized wasps remain in overwintering groups and release parasites to infect wasp larvae only later in the season. We studied the prolonged gregarious behaviour of parasitized wasps and analysed the morphology of parasitized and healthy wasps in aggregations collected over a 7-year period to determine whether the parasite affects host size, wing symmetry, ovarian development and lipid stores. All parasitized wasps were smaller and had undeveloped ovaries and more wing fluctuating asymmetry than unparasitized wasps, irrespective of time of year, parasite load and parasite sex. If infected only by one or two X. vesparum females, the wasps had large fat bodies, which could facilitate their overwintering. In contrast, wasps infected by at least one male parasite had little lipid and died at the end of the summer. Thus, X. vesparum, may play a role in the fate of its host, by exploiting wasps' tendency to form aggregations outside the colony and by altering its caste system, nutrient allocation, diapause timing and life span to achieve its own reproduction and dispersal.
... Using the above list of stereotyped behaviors, we constructed individual ethograms for each of these bouts, combined these into a single ethogram, and calculated the probabilities of specific transitions between behaviors. Enclosure studies similar to this have been performed in this lab (Starks, 1998, 2001, 2003); while it is possible that observing foraging behavior within the confines of an enclosure may have restricted the behavioral repertoire, we believe the enclosure provided reasonable resources to study general foraging behavior expressed by P. dominulus in the wild. ...
Here, we present a detailed ethogram for the foraging behavior of the eusocial paper wasp, Polistes domi-nulus. The animal's foraging process can be sub-divided into four main stages: (1) approach, (2) attack, (3) butchering, and (4) balling. Although considerable behavioral variation exists within each stage, an analysis of more than 20 individual foraging bouts reveals a single ''common path'' leading from prey approach to its transportation back to the nest; eluci-dating this path and separating it into distinct stages is useful when identifying targets for future ethological studies. Of particular interest here is the balling phase, i.e., the prepara-tion of a bolus of flesh for transportation back to the colony. Using an experimental approach, we show that foundresses can carry significantly heavier payloads than workers, sug-gesting a foraging advantage during the initial stages of colony development. We also show that wasp body mass is significantly positively correlated with payload capacity in foundresses, a relationship not seen among workers or late reproductives. This correlation suggests a beneficial adapta-tion of foundresses for combating early season pressures associated with the foundation of a new colony.
... Perhaps the earliest report of aggressive intraspecific nest takeover was the graphic description by Yoshikawa (1955). Later it was learned that intraspecific usurpation can occur commonly in some populations (Klahn 1988; Makino and Sayama 1991), and still later it was suggested that conspecific nest usurpation may, in fact, reflect ''sit and wait'' behavior as a primary reproductive tactic (Starks 1998). (It can be noted that intraspecific usurpation is commonplace in yellowjackets [Greene 1991]). ...
Two occurrences are described in which a Polistes paper wasp of one species took up residence on a nest built by and containing the brood of a different Polistes species. These observations are placed in the context of previous reports of shared nesting, intraspecific and interspecific nest usurpation, and intraspecific and interspecific adoption of orphaned nests. These observations suggest a scenario for the possible origin of social parasitism in Polistes.
... Although the data were insufÞcient for statis-tical analysis, Gamboa et al. (2002) suggested that P. dominulus does not experience intra speciÞc aggression. This observation on wild populations is somewhat at odds with those on captive populations: nest usurpation (Starks 2001), nest adoption (Starks 1998(Starks , 2001, and aggression between conspeciÞcs (Starks et al. 1998 has been observed in enclosure populations and in neutral arenas. Aggression between nest-founding wasps, however, is rare, and this observation is central to a current hypothesis for the successful invasion of some social insects (reviewed in Starks 2003a). ...
We examined the population genetic structure of an extremely successful invasive wasp, Polistes dominulus. Although successful biological invasions of social insects have been associated with genetic bottlenecks, our research uncovered an unexpected level of genetic diversity in the northeastern U.S. invasion population. Compared with a previously studied European sample, the northeastern U.S. invasion population shows no significant reduction in gene diversity and no trace of a genetic bottleneck in the putative “introduction population.” We identified multiple private microsatellite alleles in both Massachusetts and New York, which strongly suggests that the northeastern U.S. P. dominulus population arose from at least two independent introductions. Although a genetic bottleneck may enhance invasion success for some social insects, genetic and geographical data on this successful invader suggest that this wasp may represent the converse. Our results support immediate identification of genetic diversity in an invasion population before the occurrence of secondary introductions as an essential part of managing and controlling invasive species.
... Such females may be incapable of becoming or reluctant to become solitary foundresses but may be capable of becoming replacement queens upon the loss of the original queen or of usurping colonies with weak queens. Thus, our study also provides evidence for direct fitness models for the evolution of sociality discussed in the literature as the 'sit and wait' strategy (Nonacs and Reeve, 1993;Starks, 1998). We see no reason why indirect fitness models such as Hamilton's rule and direct fitness models such as 'sit-and-wait' should be mutually exclusive; wasps may be expected to gain fitness by any route available to them. ...
Social insects are characterized by reproductive caste differentiation of colony members into one or a small number of fertile queens and a large number of sterile workers. The evolutionary origin and maintenance of such sterile workers remains an enduring puzzle in insect sociobiology. Here we studied ovarian development in over 600 freshly eclosed, isolated, virgin female Ropalidia marginata wasps, maintained in the laboratory. The wasps differed greatly both in the time taken to develop their ovaries and in the magnitude of ovarian development despite having similar access to resources. All females started with no ovarian development at day zero, and the percentage of individuals with at least one oocyte at any stage of development increased gradually across age, reached 100% at 100 days and decreased slightly thereafter. Approximately 40% of the females failed to develop ovaries within the average ecological lifespan of the species. Age, body size and adult feeding rate, when considered together were the most important factors governing ovarian development. We suggest that such flexibility and variation in the potential and timing of reproductive development may physiologically predispose females to accept worker roles and thus provide a gateway to worker ontogeny and the evolution of sociality.
... And indeed, evidence exists that two of the host species discriminate colony members from non-nestmates (P. biglumis: Lorenzi et al. [1997], Lorenzi [2003]; P. dominulus: Dani et al [1996], Starks et al. [1998], and indirectly, Sledge et al. [2001b]). ...
Lorenzi, M. C. 2006: The result of an arms race: the chemical strategies of Polistes social para-sites. — Ann. Zool. Fennici 43: 550–563. The ability of social insects to discriminate between nestmates and aliens on the basis of scent has been the selective pressure favoring the evolution of chemical strategies to facilitate integration into host nests by social parasites, i.e., by organisms which rely on the nests and workers of others to rear their brood. As a result of the coevolu-tionary arms race, obligate social parasites of Polistes wasps have evolved complex mechanisms of mimicry. Social parasites mimic host chemical signatures at the level of species, colony, and possibly rank. Social parasites possess diluted recognition cues and apply compounds to the host nests that may result in host manipulation. The origin and evolutionary pathway to host/parasite chemical similarity is discussed by making comparisons with the tactics used by facultative social parasites, and with the develop-ment of the cuticular signature in free-living species.
... Polistes paper wasps are a model genus for studies of social evolution, due in part to their flexibility in colony initiation behavior (West-Eberhard 2006). Nest-founding Polistes females (foundresses) may exhibit one of several tactics, including solitary nest initiation, joining a cooperative association, usurping an existing nest, or adopting an abandoned nest (Reeve 1991; Nonacs and Reeve 1993; Starks 1998). Foundresses typically build new nests rather than reuse old combs, though nest reuse has been reported in a few species: Polistes annularis (Strassmann 1983); Polistes humilis: (Cumber 1951; Itô 1986); and some European populations of Polistes dominulus: Giovanetti et al. 1996, as cited in Cervo et al. 2000). ...
In temperate climates, female paper wasps typically initiate new colonies in the spring. Several nest-founding tactics have
been documented in Polistes species, including solitary nest initiation, joining a cooperative association, usurping an existing nest, or adopting an
abandoned nest. Occasionally, exceptionally large groups of females have also been found reusing nests from the previous season.
Here we report this phenomenon in introduced populations of the Eurasian species Polistes dominulus. We describe in detail the demographic and genetic characteristics of one such spring colony from Los Angeles, California,
USA, which was collected with 84 associated adults and all stages of developing brood in its 613 cells. Genetic and morphological
data indicate the presence of multiple reproductively active females of varying relatedness, as well as many nonbreeding females,
including probable early-produced offspring. Despite some evidence of chaotic social conditions, the colony appeared to have
been highly productive. Additional observations of similar colonies are needed to determine how control is maintained within
such a large breeding aggregation.
... P. metricus may provide an ideal opportunity for this initiative. ESTs for P. metricus are now available, and paper wasps' ecology with easily observed nests has made them the subject of extensive natural history studies [8] and a smaller number of experimental studies in captive rearing (e.g. [27]), laboratory settings (e.g. [28]), and natural environments (e.g. ...
Recent advancements in genomics provide new tools for evolutionary ecological research. The paper wasp genus Polistes is a model for social insect evolution and behavioral ecology. We developed RNA interference (RNAi)-mediated gene silencing to explore proposed connections between expression of hexameric storage proteins and worker vs. gyne (potential future foundress) castes in naturally-founded colonies of P. metricus. We extended four fragments of putative hexamerin-encoding P. metricus transcripts acquired from a previous study and fully sequenced a gene that encodes Hexamerin 2, one of two proposed hexameric storage proteins of P. metricus. MALDI-TOF/TOF, LC-MSMS, deglycosylation, and detection of phosphorylation assays showed that the two putative hexamerins diverge in peptide sequence and biochemistry. We targeted the hexamerin 2 gene in 5(th) (last)-instar larvae by feeding RNAi-inducing double-stranded hexamerin 2 RNA directly to larvae in naturally-founded colonies in the field. Larval development and adult traits were not significantly altered in hexamerin 2 knockdowns, but there were suggestive trends toward increased developmental time and less developed ovaries, which are gyne characteristics. By demonstrating how data acquisition from 454/Roche pyrosequencing can be combined with biochemical and proteomics assays and how RNAi can be deployed successfully in field experiments on Polistes, our results pave the way for functional genomic research that can contribute significantly to learning the interactions of environment, development, and the roles they play in paper wasp evolution and behavioral ecology.
... In temperate regions, the wasp has a defined four-stage colony cycle consisting of founding, worker, reproductive , and intermediate phases. Of interest has been the founding phase, during which time females initiate a nest alone, initiate a nest in association with another female (Reeve 1991), or wait to adopt an orphaned nest (Starks 1998 ). These characteristics make Polistes a model system for the study of the evolution of eusociality, kin recognition, and reproductive conflicts (see, e.g., Starks et al. 1998; Reeve et al. 2000). ...
Dominance behavior in Polistes wasps is a composite trait consisting of various discrete behaviors such as darts, lunges, bites, and mounts. The majority of these behaviors are considered "aggressive", and these aggressive behaviors are considered to form a continuum from mild (e.g., darts) to severe (e.g., falling fights). In this paper we focus on darts, the most common of the dominance behaviors, and investigate their function in un-manipulated post-emergent colonies of the primitively eusocial wasp P. fuscatus. Here we show that darts are correlated with the more severe dominance behaviors, and that dominance ranks do not change with the addition or exclusion of darts. We find no correlation, however, between receiving darts and receiving more severe dominance behaviors. This result suggests that darts are not indicative of aggressive reinforcement of dominance, but rather may serve a different function. Our data suggest that the function of darts is to regulate activity on nests. Both foundresses and workers dart inactive workers significantly more often than by chance, and workers respond to a foundress's (but not a worker's) dart by becoming less inactive. We also found that active workers who receive a dart from either a foundress or worker respond mostly by switching from one activity to another. Thus, our data suggest that darts are not aggressive behaviors, that foundresses use this signal to initiate activity, and that foundresses and workers both use the signal to regulate worker activity.
... Further, Field and Foster (1999) found no evidence for subfertility in L. flavolineata. Another possibility is that " delaying " females may be reproductively capable but following an alternative reproductive tactic of waiting to usurp established nests (Nonacs and Reeve 1993; Starks 1998 Starks , 2001). To date, there is little direct support for phenotypically manipulated disadvantages creating subordinate behavior. ...
Cooperative breeders often exhibit reproductive skew, where dominant individuals reproduce more than subordinates. Two approaches derived from Hamilton's inclusive fitness model predict when subordinate behavior is favored over living solitarily. The assured fitness return (AFR) model predicts that subordinates help when they are highly likely to gain immediate indirect fitness. Transactional skew models predict dominants and subordinates "agree" on a level of reproductive skew that induces subordinates to join groups. We show the AFR model to be a special case of transactional skew models that assumes no direct reproduction by subordinates. We use data from 11 populations of four wasp species (Polistes, Liostenogaster) as a test of whether transactional frameworks suffice to predict when subordinate behavior should be observed in general and the specific level of skew observed in cooperative groups. The general prediction is supported; in 10 of 11 cases, transactional models correctly predict presence or absence of cooperation. In contrast, the specific prediction is not consistent with the data. Where cooperation occurs, the model accurately predicts highly biased reproductive skew between full sisters. However, the model also predicts that distantly related or unrelated females should cooperate with low skew. This prediction fails: cooperation with high skew is the observed norm. Neither the generalized transactional model nor the special-case AFR model can explain this significant feature of wasp sociobiology. Alternative, nontransactional hypotheses such as parental manipulation and kin recognition errors are discussed.
... The ' wandering behaviour ' first observed by Pardi (1946) fits with recent observations of higher inter-colony mobility by parasitized P. dominulus waspsharbouring infective Xenos females -than unparasitized ones, at a time when nests were full of larvae (Beani and Massolo, 2007). This ' sit and wait strategy' for mature nests, previously hypothesized for healthy wasps which adopt/usurp colonies (Starks, 1998) as well as for social parasites (reviewed by Cervo and Dani, 1996), could be adopted by stylopized wasps to allow parasite's reproduction : a further example of parasitic manipulation of host behaviour (Hughes, 2005 ;Beani, 2006). Recent data on chemical undetectability of wasps infected by Xenos females support this alternative infection modality (Beani et al. 2005 b;Dapporto et al. 2007). ...
Host discrimination by immature host-seeking endoparasites is a complex and somewhat unexplored topic. In the case of multiple infections, conflicts among conspecifics may occur to monopolize space and resources in the same host. Two or more 1st instar larvae of Xenos vesparum (Strepsiptera, Stylopidae) may enter into a Polistes dominulus (Hymenoptera, Vespidae) larva and develop together until the adult stage of both parasite and host. We carried out a screening of mitochondrial haplotypes in X. vesparum individuals extracted from superparasitized wasps taken in 5 naturally infected nests from different areas of Tuscany (Italy), to assess whether non-sibling parasites may infect the same colony and host. In total, we obtained 12 different haplotypes out of 122 genotyped individuals of both sexes: 17 of 34 superparasitized wasps hosted parasites that originated from females differing in their haplotypes. To date, this is the first described case of superparasitism with non-sibling host-seeking larvae infecting a single individual hymenopteran host. In addition, at least in heavily infected colonies, there is evidence of a male-biased sex-ratio and synchronous development of the parasites, regardless of their haplotypes. Finally, the distribution of haplotypes per nest is consistent with either phoretic infection or larvipositing on nests by means of superparasitized wasps.
Complex problems in evolutionary biology can be approached in two ways, top down using theoretical constructs and bottom up using empirical studies . Theoretical concepts predominate evolutionary interpretations of eusociality in a literature that is small relative to an enormous literature of natural history and basic research that is not synthesized into a conceptual whole. Here, I draw insights from this literature to show how paper wasps’ allomaternal non-reproductive worker phenotype originates in every colony cycle via confluence of multiple factors of paper wasp biology. These include behavior, development, nutrient dynamics, indirect genetic effects, sex ratio, and demography. A novel perspective on the colony cycle, based on individuals’ reproductive physiology, serves as context to examine of each of these. It will be shown that the allomaternal non-reproductive worker phenotype does not require relatedness among colony members to originate. Allomaternal care of non-relatives is frequent and can occur in at least twelve contexts. Life histories of living species as they will be presented here show that relatedness among colony members is not the target of selection in simple eusociality. However, the novel allomaternal non-reproductive worker phenotype had to be present at the ancestral origins of complex eusociality in which relatedness among colony members is essential.
Darwin famously described special difficulties in explaining social evolution in insects. More than a century later, the evolution of sociality - defined broadly as cooperative group living - remains one of the most intriguing problems in biology. Providing a unique perspective on the study of social evolution, this volume synthesizes the features of animal social life across the principle taxonomic groups in which sociality has evolved. The chapters explore sociality in a range of species, from ants to primates, highlighting key natural and life history data and providing a comparative view across animal societies. In establishing a single framework for a common, trait-based approach towards social synthesis, this volume will enable graduate students and investigators new to the field to systematically compare taxonomic groups and reinvigorate comparative approaches to studying animal social evolution.
An incident of intraspecif c nest adoption involving the Japanese paper wasp Polistes jokahamae (Radoszkowski 1887) is described, in which a foundress moved to a nearby nest after leaving her original nest which contained a healthy brood. The adopted nest had been abandoned or orphaned within the previous two days. The developmental status of the broods were similar in the two nests, but the adopted nest contained more old larvae than her original nest. As such adoption has only been reported in two cases involving a Japanese paper wasp, the incident described in this present paper will signif cantly increase the understanding of the nest adoption behavior of paper wasps during the colony founding stage.
The Choros Archipelago includes three islands: Choros, Damas and Gaviota and it is part of The Pingüino de Humboldt National Reserve. These insular ecosystems are within the Chilean transitional coastal (25°-32° S). Prior researches in the archipelago reported a species of Tenebrionidae (Coleoptera) endemic to Choros island (29°15' S, 71°32' W) described as Gyriosomus granulipennis Pizarro-Araya & Flores. The objective of this paper is to evaluate the vulnerability of this species in the archipelago through Conservation Priority Index (CPI), Environmental Ministery of Chile (MMA) and Red List of IUCN. We concluded that G. granulipennis is Endangered by CPI index, and Vulnerable by MMA of Chile. Additionally, this species can be classiffi ed with Defi cient Data (DD) by IUCN because many of data are impossible or diffi cult to obtain for insects and can overestimate or underestimate the risk of extinction of this species. We consider important to monitoring the continuity of this species and the protection of habitat, for which we propose not allow access the tourists and eradication of European rabbit.
CHAPTER SUMMARY Discrete, alternative reproductive tactics (ARTs) occur in most orders of insects, across a wide array of mating systems, and during all steps in the reproductive process (locating a mate, gaining access to him/her, copulating, and post-copulatory behavior). ARTs for mate searching are particularly common and often involve a division between high-investment or high-risk but sedentary, nondispersing tactics and low-investment or low-risk but active, dispersing, searching tactics with longer-range movements. ARTs in insects are often associated with intense sexual selection and include individuals that avoid costly or high-risk intrasexual interactions, parasitizing the costly investment of others, or circumventing intersexual interactions and mate conflict. Two or more tactics can arise in a population when opportunities for success are discrete and require different and mutually exclusive behavior or morphology. Suites of distinctive, correlated traits arise through condition-dependent, developmental switches and when there is selection against individuals with intermediate traits (disruptive selection). ARTs are maintained in populations by frequency dependence and equality of fitness among tactics or as condition- or environment-dependent alternatives that maximize individual fitness. THE PROBLEM Discrete, alternative reproductive tactics (ARTs) within one sex and one population occur in most groups of insects (Table 8.1). For example, nonflying, large-headed, fighting males live in the nests of some female halictid (Kukuk and Schwarz 1988) and andrenid bees (Danforth 1991b) and mate with females inside the nest just prior to oviposition; while smaller, flying males with normal-looking heads and mandibles mate with females outside the nest as they forage on flowers (Danforth 1991b) (Figure 8.1). © Cambridge University Press 2008 and Cambridge University Press, 2009.
We simulated intraspecific usurpation in two species of paper wasps at a field site in Michigan to compare the species' treatment of foreign brood. Queens of Polistes fuscatus, a species that commonly uses intraspecific usurpation as an alternative reproductive tactic, destroyed significantly fewer large larvae and significantly more small larvae than queens of P. dominulus, a sympatric species that rarely usurps. The pattern of brood destruction exhibited by P. fuscatus was consistent with the previously published findings that P. fuscatus usurpers destroy reproductive‐destined brood (eggs and small larvae), but not worker‐destined brood (large larvae and pupae) that are subsequently used by a usurper to raise her own reproductives. The pattern of brood destruction displayed by P. dominulus differed from that of Polistes species that frequently engage in intraspecific usurpation. The brood destruction pattern in P. dominulus may have been shaped by nest adoption, a common alternative reproductive tactic in this species. If so, it is not clear why P. dominulus would destroy large, worker‐destined larvae.
The benefits of cooperation are essential in driving group formation. However, an individual can gain significant benefits by acting selfishly at a substantial cost to others in the group. Thus, group members must find a balance between accepting and rejecting potential new members. Here, I explore the factors that mediate acceptance of non-related individuals during the period of group establishment in the primitively eusocial wasp Mischocyttarus mexicanus. In this species, group composition changes during establishment, with non-related females (non-nestmates) sometimes accepted into a foreign colony. By experimentally introducing non-nestmates to newly established colonies, I test the hypothesis that acceptance threshold of nestmates towards non-nestmates shifts depending on the ecological context, as predicted by the Optimal Acceptance Threshold Model. I explored how non-nestmate age (young vs. old), stage of colony establishment (early vs. late), initial behavior of the non-nestmates (non-aggressive vs. aggressive), and the behavioral response by nestmates (non-aggressive vs. aggressive) affected the rates of acceptance. My results show an effect of both non-nestmate age and stage of colony development on non-nestmate acceptance. Young non-nestmates were more frequently accepted in early than in late colonies. Late colonies more frequently rejected both young and old non-nestmates, suggesting a cost of accepting potential usurpers into late colonies. Surprisingly, non-nestmate aggressive behavior did not have a direct effect on their acceptance, but it triggered an aggressive response from nestmates. These findings reveal a shift in the acceptance threshold, suggesting an effect of the social context and the specific needs of a colony on non-nestmate acceptance.
Within-group power asymmetries and the resulting reproductive skew, common in most social groups, may effectively be set at the very early stages of group formation, that is, when group membership is determined. Hence, groupmate choices can define an individual's future reproductive success. We examined how groups of Polistes dominulus formed under natural, unconstrained conditions, using data on the nesting history, kinship and morphology of individually marked foundresses obtained during two consecutive seasons in southern Spain. Foundresses that hibernated in the same aggregation were more likely to start a nest together, but all of the foundresses at a nest were seldom from a single aggregation. Changes in group composition were frequent throughout the preworker period, mainly because some foundresses disappeared and other wasps joined established groups. Within-group relatedness, however, was not affected by the late arrival of wasps. Our results suggest that waiting to join an established group is a common nesting strategy in P. dominulus. Only 16% of marked wasps used more than one nest. Foundresses that moved between groups tended to move to groups in which genetic relatedness among the resident foundresses was higher, but not necessarily relatedness to the moving wasp herself. Overall, nestmate choices were not associated with a single factor. High failure rates, particularly of single-foundress nests, however, suggest that ecological constraints (e. g. risk of predation, lack of resources) may have a stronger effect on individual nesting choices than previously considered.
Social behavior occurs in some of the smallest animals as well as some the largest, and the transition from solitary life to sociality is an unsolved evolutionary mystery. The Evolution of Social Wasps examines social behavior in a single lineage of insects, wasps of the family Vespidae. It presents empirical knowledge of social wasps from two approaches: one that focuses on phylogeny and life history; and one that focuses on individual ontogeny, colony development, and population dynamics. It also provides an extensive summary of the existing literature while demonstrating how it can be clouded by theory. This approach to the conflicting literature on sociality highlights how often repeated models can become fixed in the thinking of the scientific community. Instead, it presents a mechanistic scenario for the evolution of sociality in wasps that changes our perspective on kin selection, the paradigm that has dominated thinking about social evolution since the 1970s.
Philopatric behavior has been demonstrated in a wide taxonomic spread of animals. In temperate environments, overwintered Polistes wasp foundresses often return to their natal nest prior to initiating colony construction. Previous research has shown that these spring foundresses can identify the natal nest in the absence of landmark and gross morphological cues. Hydrocarbons are essential recognition cues for Polistes nest and nestmate discrimination, but cuticular hydrocarbon profiles can become homogenized when foundresses overwinter in mixed colony groups. We examined the hydrocarbon profiles of Polistes dominulus foundresses and nests before and after an overwintering period, and found that the hydrocarbon profiles of nests remain unique over time and that this uniqueness is influenced by the original foundresses. Our data raise the possibility that in returning to the natal nest, foundresses reacquire their colony-specific signature, which may play a role in the formation of cooperative associations.
Timing of diapause termination has an important influence on individual reproductive success, but relatively little research
has explored how individuals differ in their response to diapause termination cues. We tested individual variation in the
timing of post-diapause activity in Polistes dominulus paper wasps. Wasps were overwintered in a temperature-controlled chamber. In the spring, ambient temperature was gradually
increased and the time each foundress became active was recorded. Timing of post-diapause activity was most strongly associated
with the facial patterns that function as a conventional signal of quality. Foundresses with facial patterns indicating high
quality became active at lower temperatures than individuals with facial patterns indicating low quality. Early diapause termination
is associated with dominance, so the relationship between diapause termination and facial patterns provides a mechanism linking
facial patterns with dominance. Body weight and mating status did not influence timing of post-diapause activity. Juvenile
hormone (JH) titer at the time of diapause termination was also measured in a subset of foundresses. There was no JH titer
threshold for diapause termination. Instead, our results suggest that individuals may have different threshold responses to
JH, as individuals that became active at a lower temperature had lower JH titers than individuals that became active at a
higher temperature. Overall, there is substantial individual variation in response to diapause termination cues and the variation
is likely to have important impacts on the fitness of nest-founding females.
KeywordsDominance–Juvenile hormone–Diapause–Quality signal
Social insects are excellent invaders that have had negative impacts on native species and humans. Many invasive species move
from warmer to cooler climates. For these species, thermal adaptations may both be important for their ability to invade and
to limit their invasion range. The invasion of Polistes dominulus into North America provides an example of a primitively eusocial invader from a warmer climate. We studied the differences
in thermoregulation between P. dominulus and the native P. fuscatus. We found that, during flight, thorax temperature in P. fuscatus was less affected by ambient temperature than thorax temperature of P. dominulus. We also found that P. dominulus and P. fuscatus showed different patterns of warming after removal from a cold environment. Unlike P. dominulus, live P. fuscatus never fully cooled down in a cold environment. P. fuscatus also reached their relative minimum flight temperatures earlier than P. dominulus, but P. dominulus maintained higher elevated temperatures for longer. These differences in thermoregulatory ability suggest that the lower
winter survival of P. dominulus could be offset by a greater thermal tolerance during flight, while the lower thermal tolerance of P. fuscatus in flight is offset somewhat by better thermoregulatory ability.
KeywordsExotic species–Hymenoptera–Eusociality–Thermoregulation
Summary: Polistes dominulus, a common Polistes species with Old World distribution, is now invading the United States. We discuss those characteristics of P. dominulus that may explain its successful establishment in its new American environment. A versatile diet, the ability to colonize new environments and a short development time of the immature brood might have played an important role in the rapid spread in P. dominulus.
Polistes wasps can initiate colonies by themselves, but spring foundresses often cooperate in constructing a shared nest and raising a common brood. The relative benefits for such cooperation vary across environmental and social contexts and thus foundresses should shift reproductive strategies when contexts change. An experimental study of 10 field populations of P. dominulus provides evidence for such strategy shifts. P. dominulus females displayed three basic alternative reproductive strategies: initiate a nest alone or as a dominant on a multifoundress nest, join as a subordinate, or refrain from nesting and instead ''sit-and-wait'' for reproductive opportunities to open later in the season. In our populations, joining likely yields inclusive fitness benefits by increasing colony survival and resistance to usurpation. Nevertheless, joiners and other foundresses readily moved to improve their situations by (1) adopting orphaned nests. (2) switching to larger nests, and (3) usurping small nests, which may have had a weakened foundress or a foundress with relatively low motivation for nest defense. Joining occurring more often early in the season, and adopting and usurping occurring more often later were consistent with inclusive fitness maximization. Lost past investments in nests did not affect future decisions. Overall, residents of nests were larger than the wasps that joined them, but this difference decreased over the course of the season. Wasps that had cooperated in the past to form multifoundress associations were more likely to renest (usually together) after removal of their original nest than were single foundresses. After nest loss, single foundresses were more likely than multiple foundresses to take over another wasp's nest by adoption or usurpation. Cooperation within multifoundress associations is facultative and the balance between cooperation and conflict theoretically depends on the asymmetry in reproduction resulting from the asymmetry in dominance. P. dominulus cofoundresses closer in size (less asymmetrical in dominance) added cells to their nests more slowly and produced significantly smaller nests and fewer workers than associations with more size variation, as would be predicted by greater conflict between wasps that are closer in size. The decline in size differences between joining wasps and residents suggests that late-season joiners were relatively large wasps seeking to dominate residents. Conflict on the nest may also explain why multiple foundresses disappeared from nests at a higher rate than did single foundresses. In sum, the multiple reproductive options of P. dominulus lead to a dynamic and flexible balance between cooperation and conflict in their social interactions.
We present a simple, general model of how the optimal level of intragroup aggression should vary in different social contexts. A key component of this model is the Value of the recipient of aggression to a potential aggressor (i.e., the ratio of expected long-term group productivity with the recipient present to the expected group productivity with the recipient absent). The recipient's Value measures its contribution to group reproductive success. We demonstrate theoretically that if aggression increases the aggressor's share of the group's expected total reproductive output, but at the same time decreases the magnitude of this overall reproductive output, then the optimal level of aggression toward a recipient will decrease with increasing recipient's value. This proof establishes a rigorous theoretical connection between the level of aggression within a group and the benefits of belonging to such a group and can be tested by experimentally manipulating the values of group members to each other. We test, and thus illustrate the utility of, this model by examining aggression within experimentally-manipulated foundress associations of social wasps. We show that the value of co-foundresses to each other in the social wasp Polistes fuscatus lies in their ability to provide insurance against colony failure caused by the loss of all tending foundresses. Removals of worker-destined eggs and pupae, which increase the value of co-foundresses, both lead to significant reductions in aggression by the dominant foundress, despite the fact that the immediate, selfish benefits of competitive aggression should increase when empty brood cells are present. Removal of reproductive-destined eggs, which does not affect co-foundress value, but increases the benefits of selfish aggression, causes a significant increase in aggression by beta foundresses. Finally, wing reduction of subordinate co-foundresses significantly increases aggression by dominant foundresses, as expected since the subordinate's value is reduced. Our results indicate that foundress aggression is sensitive to the value of future cooperation, as predicted by the optimal aggression model. The model may apply widely to both invertebrate and vertebrate societies.
I present a hierarchy of models that illustrate, within the framework of inclusive fitness theory, how demographic factors can predispose a species to the evolution of eusociality. Delayed reproductive maturation lowers the inclusive fitness of a solitary foundress relative to that of a worker. Variation in age at reproductive maturity makes the worker strategy more profitable to some individuals than to others and thus predicts the coexistence of single-foundress and multiple-foundress nesting associations. Delayed reproductive maturation and variation in age at reproductive maturity also select for mixed reproductive strategies so that some individuals whose reproductive maturation is expected to be delayed can first act as workers and later switch over to the role of a queen or foundress. Assured fitness returns shows how identical mortality rates can have different consequences for workers and solitary nest foundresses because a solitary foundress will have to necessarily survive for the entire duration of development of her brood, whereas a worker can hope to get proportional fitness returns for short periods of work. In concert with assured fitness returns, delayed reproductive maturation and variation in age at reproductive maturity become more powerful in selecting for worker behavior, and mixed reproductive strategies become available to a wider range of individuals. These phenomena provide a consistently more powerful selective advantage for the worker strategy than do genetic asymmetries created by haplodiploidy.
The diversity of social behavior among birds and primates is surpassed only by members of the Hymenopteran insects, including bees, ants, and the genus Polistes, or paper-wasps. This volume combines incisive reviews and new, unpublished data in studies of paper-wasps, a large and varied group whose life patterns are often studied by biologists interested in social evolution. While this research is significant to the natural history of paper-wasps, it also applies to topics of general interest such as the evolution of cooperation, social parasitism, kin recognition, and the division of labor.
Starks, P. T. 2003: Natal nest discrimination in the paper wasp, Polistes dominulus. — Ann. Zool. Fennici 40: 53–60. I present data indicating that Polistes dominulus females overwinter in multi-colony groups, recognize natal nest fragments after overwintering, and select nesting cavi-ties based on cavity volume. In a seminatural environment, seven fi eld-captured P. dominulus colonies completed the colony cycle, and the resulting reproductive females were observed in hibernacula groups, on natal nest fragments prior to colony initiation, and in nest boxes after initiating colonies. Given the choice of three nest box sizes in which to initiate colonies, P. dominulus preferred medium nest boxes and avoided large nest boxes. This site preference may indicate a balance between the cost of detec-tion by predators and the benefi t of space for colony growth. Even though natal nests were cut into small fragments and distributed into nest boxes, spring foundresses rec-ognized and preferentially perched upon fragments from their natal nest. Individuals whose natal nest contained multiple queens were signifi cantly more likely to perch upon natal nest fragments than were individuals whose natal nest contained a single queen. Returning to and recognizing the natal nest may be an adaptive mechanism to (A) locate nestmates with whom to initiate multiple foundress colonies and (B) reduce the cost of fi nding these nestmates.
Incidents of usurpation were observed in colonies of Polistes fuscatus nesting on farm buildings (1977–79) and in nestboxes (1980–84) in Johnson County, Iowa, USA. Most usurpations (84.8%) occurred in the latter half of the preworker phase of the colony cycle, which coincided with periods of high predation of combs by vertebrates. Usurpers were probably displaced single foundresses which did not join neighbors or refound colonies after comb loss. Most (89–100%) usurpers of known relatedness to the foundresses they replaced were cousins or less related to them. Usurpation was a significant source of nest loss (19.6%) among single foundresses, but was rare (2.2%) in multiple-foundress colonies and colonies with workers (3.5%). Usurpers often destroyed younger brood (eggs and larvae in instars 1–3) in host colonies, while older larvae and pupae were usually spared. Brood destruction was more pronounced in more advanced host combs. Usurper survivorship after workers eclosed was lower than than of queenright single foundresses (61.5% vs 87.0%). Reproductive success by usurpers was less than that of queenright single foundresses, but greater than that of foundresses which initiated colonies late in the preworker colony cycle.
Adoption of abandoned or orphaned nests by adult females occurs commonly during the colony-founding period of the primitively eusocial paper wasp, Polistes dominulus. Our evidence indicates that adoption reflects: (1) ‘making the best of a bad situation,’ for queens who have lost their nests; (2) subordinates leaving multiple-foundress associations; and (3) possibly, a ‘sit-and-wait’ strategy, in which non-nesting females wait for nests to be orphaned. A ‘it-and-wait strategy’ implies that wasps facultatively delay personal reproduction rather than that the delay in reproduction is due to physiological constraints (sensu Gadagkar, 1991a). Orphaned nests with related brood are not more attractive than those bearing unrelated brood, suggesting that nest-adoption has not evolved primarily as a strategy to rescue non-descendant kin. Instead, all wasps tend to adopt nests that theoretically maximize their selfish genetic interests: the most attractive nests were large combs at an advanced stage of development. These nests can produce more workers and are closer to worker emergence, at which time colony survival per unit time dramatically rises. The primary proximate cue for adoption seems to be whether nests contain later-instar larvae or pupae. Since developmental stage of brood correlates with nest size, preferred nests thus tend to be relatively mature and large.
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