Information analysis by the paper wasp,Polistes fuscatus,during nest construction (Hymenoptera,Vespidae)

Summary The building decision process of the paper wasp,Polistes fuscatus, was studied by 1) analyzing the search pattern of the wasps prior to the addition of pulp to different areas of the nest, 2) comparing the pulp addition needs of the cell chosen for lengthening to those of other cells in the nest, and 3) presenting the wasps with eight types of dichotomous building choices, which provided information about the relative influence of different building cues. Wasps conduct a hierarchical search prior to pulp addition, which means that they search the comb face and petiole disproportionately more often and more thoroughly than the comb back and sides. Once a particular nest area triggers closer scrutiny, comparisons are made with adjoining areas. The most needy location is then chosen based on nest cues. When lengthening a cell, the development of the brood and relative cell length have a strong influence on which cell is chosen at all times, while distance of the brood from the cell mouth becomes important during the later stages of brood development. The results indicate that there is no simple hierarchical weighting of cues. The decision process involves comparisons among multiple cues, which for the most part have an additive influence when variation in relative cue strength is considered.     

Lateral Vibrations by Social Wasps Signal Larvae to Withhold Salivary Secretions (Polistes fuscatus, Hymenoptera: Vespidae)

The communicative meaning of an oscillation (lateral vibration) performed by foundresses of social wasps (Polistes fuscatus) was investigated by sampling larval saliva from 12 postworker, single-foundress colonies and by viewing videotapes of 17 multiple-foundress (139.3 h) and 16 single-foundress (32 h) preworker colonies. Foundresses spent significantly more time inspecting cells before performing a lateral vibration (LV) than after and commonly became inactive after performing an LV. The proportion of departures temporally proximate to LVs was significantly greater in single- than in multiple-foundress colonies. Departures and LVs were significantly temporally associated in single-foundress colonies. Single foundresses were significantly more likely to perform an LV prior to departing on longer than shorter trips. In multiple-foundress colonies there was a significant temporal relationship between LVs and departures that left the nest unattended. Larvae secreted significantly less saliva, a nutritious substance provided to adults, immediately after an LV than in the absence of an LV. Contextual evidence and results of sampling larval saliva indicate that LVs by foundresses signal larvae to withhold or reduce their secretion of saliva.     

The comparative biology of two sympatric paper wasps, the native Polistes fuscatus and the invasive Polistes dominulus (Hymenoptera, Vespidae)

Summary: Polistes dominulus (Christ), an old world paper wasp, was introduced accidentally into the eastern coast of the United States in the late 1970s and has been rapidly spreading westward, displacing the native P. fuscatus (F.). The biology of naturally nesting P. fuscatus and P. dominulus was compared at a field site in Rochester, Michigan. The basic methodology consisted of simultaneously videotaping spatially proximate, matched single-foundress colonies of P. fuscatus and P. dominulus (13 matched sets, 176.8 h of videography). In addition, extensive surveys and censuses were taken of colonies to record colony productivity, dates of nest initiation and first worker emergence, usurpation and parasitism.¶There was no evidence that P. dominulus is negatively impacting P. fuscatus through direct, agonistic encounters. However, P. dominulus is 4-5 times more productive than P. fuscatus, suggesting that P. dominulus is replacing P. fuscatus via exploitative competition. P. dominulus appears to have a number of advantages over P. fuscatus, including earlier production of workers, higher per capita foraging rates by queens and workers, higher queen survivorship, and lack of conspecific pressures. Nest site and/or prey availability may be limiting factors in the competition between the two species.     

Hole repair and the influence of learning on nest repair in the paper wasp,Polistes fuscatus (Hymenoptera: Vespidae)

Two methods of hole repair used by the paper wasp, Polistes fuscatus,were examined and compared, and the hypothesis that nest repair behavior may improve with experience was tested. Similarly sized holes were repeatedly made in the sides of nests and the repair behavior of the nest residents was recorded. The distance of the hole from the cell mouth determined which repair method was used. In addition, both the amount of time for hole repair completion and the number of pulp loads used in making the repair decreased significantly with experience.     

Queens of the Paper Wasp Polistes fuscatus (Hymenoptera: Vespidae) Discriminate among Larvae on the Basis of Relatedness

The ability of queens of the paper wasp Polistes fuscatus to recognize larvae on the basis of colony origin was investigated in the laboratory. In a blind, binary choice paradigm, queens discriminated between larvae from their own colony and unrelated larvae, and between larvae from a sister colony and unrelated larvae. However, queens failed to discriminate between larvae from their own colony and larvae from a sister colony, indicating that queens of multiple-foundress colonies may lack the ability to make intracolonial brood discriminations on the basis of relatedness. These results demonstrate that recognition of larvae is mediated by larval-borne, genetically specified odors. Gas chromatograph/mass spectral analysis revealed that adults and larvae have similar cuticular hydrocarbon profiles, suggesting that the cues mediating larval and adult recognition may be the same.     

A role of the Dufour's gland in the dominance interactions of the paper wasp,Polistes fuscatus (Hymenoptera: Vespidae)

The Dufour's gland of the paper wasp, Polistes fuscatus,is a source of the cues used by dominant females to recognize the eggs laid by subordinates or nonnestmates on pre (worker)-emergence nests. When dominant wasps were presented with an egg covered with either (1) the Dufour's gland extract of a subordinate cofoundress, (2) the extract of an egg from the same subordinate, or (3) the solvent alone, the dominant female destroyed and replaced the eggs covered with the Dufour's extract significantly more frequently than the other eggs. Eggs with the extract of a nonnestmate's Dufour's gland were also eaten significantly more frequently than those with the solvent. Given similar choices, subordinates did not destroy any eggs. The Dufour's gland appears to have little or no role in communicating dominance directly among aggressively interacting cofoundresses.     

Hilltopping Behavior of Polistes commanchus navajoe (Hymenoptera: Vespidae)

Males of the paper wasp Polistes commanchus aggregate in large numbers on hilltops in central and southeastern Arizona where individual males defend perch sites on shrubs, trees or rocks. Residents chase intruders away quickly and exhibit strong site fidelity at their perches. Takeovers are rare as are prolonged battles for possession of a site. Males have only weak preferences for peaktop perch sites as opposed to those lower on hillsides, and a similarly weak preference for perches in shrubs as opposed to those on rocks. Receptive females appear occasionally at the male aggregation sites to mate with perch holders. The relatively weak territoriality exhibited by P. commanchus may stem in part from the high density of males at peaktops and the correspondingly high rate of interactions. The evolution of hilltopping in a species whose reproductive females are clumped spatially at nest sites poses a puzzle for the ecological analysis of mating systems.     

Nesting Habit and Alarm Pheromones in Polistes gallicus (Hymenoptera, Vespidae)

Alarm pheromones are used in many social insects to elicit an alarm response of nestmates towards disturbances. This chemical alarm channel is especially used by species nesting in closed environments. Polistes gallicus paper wasps typically found their nests on open substrates where visual and vibrational stimuli could be more important than the chemical one to alarm the colony. We investigated, through field bioassays, if, also in this species, workers venom is still the source of alarm pheromones. Our results show that venom volatiles are able to increase the colony defence reaction stimulating more individuals to attack and sting the object of disturbance. Therefore our results suggest the hypothesis that chemical alarm is independent of nesting habit (concealed vs exposed) within the Polistes genus.     

The role of parasitoids in regulation of Polistes wasp population (Hymenoptera, Vespidae: Polistinae)

The study conducted in 2005–2010 analyzes the behavioral response of the parasitoids Latibulus argiolus (Rossi) (Hymenoptera, Ichneumonidae) and Elasmus schmitti Ruschka (Hymenoptera, Eulophidae) to the distribution of their host, Polistes wasps (Hymenoptera, Vespidae). Various conditions of the parasitoid-host system and conditions of regulation of the host abundance are discussed. The parasitoid females are more active in wasp colony clusters and tend to infest larger nests. If the parasitoids are abundant, infestation of host colonies starts earlier, sometimes before the worker emergence; therefore, density-dependent behavioral response of parasitoids is caused primarily by the impact of the aggregation component. Thus, the host population density factor appears to be mediated not only by the non-uniform development rates of colonies and their spatial distribution, but also by the seasonal (temporal) aspect of their development. Low density of the host population, at which the parasitoids regulate the wasp abundance, corresponds to a certain phase of the seasonal colony development, namely to the period before the emergence of workers. On the whole, we are dealing with a host-parasitoid system in which the spatial and temporal factors are closely interrelated.     

Cuticular hydrocarbon dynamics in young adult Polistes dominulus (Hymenoptera: Vespidae) and the role of linear hydrocarbons in nestmate recognition systems

In social insects, cuticular hydrocarbons (CHCs) play an important role in nestmate discrimination processes, but young individuals are usually not discriminated. We studied CHC changes in young workers of the social wasp Polistes dominulus. A quantitative estimation demonstrated that total quantities of CHCs increased after emergence, with branched alkanes increasing drastically when compared with other classes of hydrocarbons. The relative quantity of longer-chain compounds increased with respect to shorter ones; unsaturated compounds decreased. These changes might reduce the capacity of the cuticle to acquire compounds of environmental origin. We then tested whether individuals acquire hydrocarbons from the environment, and whether this capability equally characterises newly emerged and mature wasps. We exposed wasps of two age classes (adults younger or older than 24 h) to four linear hydrocarbons in turn, and observed how nestmates reacted to their re-introduction into the natal colony. Exposed young wasps elicited significantly more aggressive responses than control sisters; but treated wasps older than 24 h were generally accepted by nestmates. Chemical assays showed that exposed young wasps readily absorbed hydrocarbons; older ones did not incorporate hydrocarbons, suggesting that the chemical profiles of mature wasps are less prone to chemical shifts than those of newly emerged wasps.     

Male Reproductive Behavior of the Social Wasp Polistes fascatus (Hymenoptera: Vespidae)

Populations of male Polistes fuscatus simultaneously exhibit two different mate-locating tactics. Some males defend territories in female nesting and hibernation sites. These males frequently do not occupy the same territory each day, and they drag their gasters over perches, which may function to apply a secretion to the perch. Another segment of the population patrols large overlapping areas in female foraging sites. In contrast to territorial males, patrolling males do not rub their gasters on perches, and males seen on more than one day are tenacious to one area. Males in both sites are aggressive to other males and attempt to copulate with females. A laboratory study indicates that large males have an advantage in male-male competition. The mean size of patrollers is smaller than that of territorial males, indicating that patrollers are competitively inferior males. Yet there is considerable size overlap of males between the two sites, suggesting that there is also overlap in the range of probability of mating success between the two sites.