Insect societies require an effective communication system to coordinate members' activities. Although eusocial species primarily use chemical communication to convey information to conspecifics, ...there is increasing evidence suggesting that vibroacoustic communication plays a significant role in the behavioural contexts of colony life. In this study, we sought to determine whether stridulation can convey information in ant societies. We tested three main hypotheses using the Mediterranean ant Crematogaster scutellaris: (i) stridulation informs about the emitter'caste; (ii) workers can modulate stridulation based on specific needs, such as communicating the profitability of a food resource, or (iii) behavioural contexts. We recorded the stridulations of individuals from the three castes, restrained on a substrate, and the signals emitted by foragers workers feeding on honey drops of various sizes. Signals emitted by workers and sexuates were quantitatively and qualitatively distinct as was stridulation emitted by workers on different honey drops. Comparing across the experimental setups, we demonstrated that signals emitted in different contexts (restraining vs feeding) differed in emission patterns as well as certain parameters (dominant frequency, amplitude, duration of chirp). Our findings suggest that vibrational signaling represents a flexible communication channel paralleling the well-known chemical communication system.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Social insects have evolved sophisticated recognition systems enabling them to accept nest-mates but reject alien conspecifics. In the social wasp, Liostenogaster flavolineata (Stenogastrinae), ...individuals differ in their cuticular hydrocarbon profiles according to colony membership; each female also possesses a unique (visual) facial pattern. This species represents a unique model to understand how vision and olfaction are integrated and the extent to which wasps prioritize one channel over the other to discriminate aliens and nest-mates. Liostenogaster flavolineata females are able to discriminate between alien and nest-mate females using facial patterns or chemical cues in isolation. However, the two sensory modalities are not equally efficient in the discrimination of ‘friend’ from ‘foe’. Visual cues induce an increased number of erroneous attacks on nest-mates (false alarms), but such attacks are quickly aborted and never result in serious injury. Odour cues, presented in isolation, result in an increased number of misses: erroneous acceptances of outsiders. Interestingly, wasps take the relative efficiencies of the two sensory modalities into account when making rapid decisions about colony membership of an individual: chemical profiles are entirely ignored when the visual and chemical stimuli are presented together. Thus, wasps adopt a strategy to ‘err on the safe side’ by memorizing individual faces to recognize colony members, and disregarding odour cues to minimize the risk of intrusion from colony outsiders.
Full text
Available for:
BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Honeybee disappearance is one of the major environmental and economic challenges this century has to face. The ecto-parasitic mite Varroa destructor represents one of the main causes of the worldwide ...beehive losses. Although halting mite transmission among beehives is of primary importance to save honeybee colonies from further decline, the natural route used by mites to abandon a collapsing colony has not been extensively investigated so far. Here, we explored whether, with increasing mite abundance within the colony, mites change their behaviour to maximize the chances of leaving a highly infested colony. We show that, at low mite abundance, mites remain within the colony and promote their reproduction by riding nurses that they distinguish from foragers by different chemical cuticular signatures. When mite abundance increases, the chemical profile of nurses and foragers tends to overlap, promoting mite departure from exploited colonies by riding pollen foragers.
One of the main tasks a freshly mated ant queen has to face is to find a safe and suitable nest site to start a new colony. Colony foundation by associated queens, also known as pleometrosis, has ...been described for several ant species and, under specific selective pressures, represents an alternative to independent colony foundation. Despite most newly mated queens of the common Mediterranean acrobat ant
Crematogaster scutellaris
generally adopting independent colony foundation inside tree trunks, both field and laboratory studies have demonstrated that the formation of pleometrotic groups may occur, particularly inside lignified aphid galls on poplar or oak trees. These associations typically end with the survival of only one queen after the foundation phase, and the benefits they may provide remain unclear. In this study, we investigated how queen density and different nest availability may promote the formation of pleometrotic associations in
C. scutellaris
. We found that occupied nests are not actively sought after by queens, as hypothesised in previous studies, but might be accepted when they are the only safe refugia available. Moreover, the tendency to form groups increases as queen density increases, and nest availability is a limiting factor. Finally, we found no evidence that the size of the queen affects whether to join an already occupied nest.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Discrimination among potential partners is a critical step in sexual selection to avoid wasting reproductive resources on an unsuitable mate. In the female-dominated hymenopteran societies males have ...often been regarded as ‘flying sperm containers’ spending all their time and energy in trying to acquire a mate. We investigated the male sexual preference for potential partners using as a model the primitively eusocial wasp Polistes dominula in which female caste is rather flexible and difficult to determine. By means of laboratory bioassays, we compared the males' behaviour towards females of different reproductive potential. Males were able to recognize female castes, strongly preferring reproductive females to workers, regardless of female age or health. The results show that in this species caste plays a key role in orienting male discrimination and preference, presumably through chemical cues, towards reproductive females both healthy and parasite-castrated. Overall, our study shows that social Hymenoptera males are not always ‘small mating machines’ eager to mate.
•We investigate sexual selection from the point of view of males in a social wasp.•Males were able to recognize cryptic female castes.•But males were unable to recognize a female's reproductive potential.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
To establish a dominance order, social animals often rely on indicators of fighting to avoid costly aggressive encounters. In some species, individuals use colour patterns to signal their social ...status. Recent studies claimed that facial markings in the eusocial paper wasp Polistes dominulus are status badges that allow co-foundresses to form a linear hierarchy based on individual quality. Here, we evaluated facial patterns in natural populations of P. dominulus, in its native range, to observe whether the marks reflect overall wasp quality in different contexts. We used the same measures of clypeus patterns used by earlier studies, but did not find that they functioned as status badges. Our analyses showed no evidence that visual markers are related to: (i) size, (ii) probability of surviving winter, (iii) social rank in spring associations, or (iv) health status (assessed by the presence of strepsipteran endoparasites). Size, however, is important. Larger wasps are more likely to survive the winter and to acquire the dominant position in spring associations. Larvae infected with endoparasites become smaller adult wasps. These findings suggest that body size is a reliable quality indicator on which wasps build their social networks, and that clypeus patterning is not involved.
Full text
Available for:
BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
In recent years, a number of studies have suggested that visual status signaling operates in social wasps. In the paper wasp
Polistes dominula
, status is thought to be signaled by a region of black ...pigmentation on the yellow clypeus. Specifically, studies of the invasive North American population have indicated that the clypeal patterning of
P. dominula
females conveys information on their agonistic abilities in various natural contexts such as dominance within the nest and competitive interactions. However, studies of native European populations have, so far, failed in demonstrating such a function of the clypeal patterning. The present work investigated the status signaling in an Italian population of this species, eliminating any chemical and behavioral factors of the signaler and controlling for signaler size, therefore, focusing on visual stimulus alone. Using tightly controlled laboratory settings, we performed two bioassays representing two distinct natural contexts: a competitive interaction over food resources and a nest defense scenario. To this end: (1) we offered to future foundresses food patches guarded by two odorless conspecific lures differing only in visual facial cues and (2) we presented odorless wasp lures with a different clypeal patterning to solitary foundresses defending their own nest. We found no evidence for any role of the clypeal patterning in the rival assessment in both contexts. Hence, we conclude that
P. dominula
foundresses belonging to the Italian population lack visual status signaling on their clypeus. Further studies will elucidate factors and mechanisms underlying the geographical variation and evolution of visual signals in paper wasps.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Both recognition and conventional signals are widespread in the animal kingdom. Chemical communication plays a major role in invertebrates, and especially in social insects. In the last decade, ...observational and experimental evidence has shown the existence of visual quality signals and individual recognition cues in Polistes paper wasps, meaning that visual communication might also be common in insect societies. Here we show that two species of facultatively eusocial hover wasps (Vespidae, Stenogastrinae) use the visual channel for social communication. By combining morphoanatomical measurements and behavioural assays, we found that the size of the dark facial markings was related to reproductive status and dominance in colonies of Liostenogaster vechti, thus representing a badge of status. By contrast, no correlation between facial coloration and reproductive status was found in Liostenogaster flavolineata, which instead used facial markings as familiar visual recognition cues. Our results reveal that visual communication in social insects might be more widespread than previously thought and has evolved independently in distinct wasp taxa facing similar selection pressures.
► We demonstrated that Stenogastrinae wasps use facial marking for visual communication. ► Facial markings are related to reproductive status in Liostenogaster vechti. ► L. vechti facial marking represents a badge of status. ► No correlation was found between facial marking and dominance in L. flavolineata. ► L. flavolineata uses facial markings as visual recognition cues among nestmates.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Members of the odorant-binding protein (OBP) and chemosensory protein (CSP) families were identified and characterised in the sensory tissues of the social wasp Polistes dominulus (Hymenoptera: ...Vespidae). Unlike most insects so far investigated, OBPs were detected in antennae, legs and wings, while CSPs appeared to be preferentially expressed in the antennae. The OBP is very different from the homologous proteins of other Hymenopteran species, with around 20% of identical residues, while the CSP appears to be much better conserved. Both OBP and CSP, not showing other post-translational modifications apart from disulphide bridges, were expressed with high yields in a bacterial system. Cysteine pairing in the recombinant and native proteins follows the classical arrangements described for other members of these classes of proteins. OBPs isolated from the wings were found to be associated with a number of long-chain aliphatic amides and other small organic molecules. Binding of these ligands and other related compounds was measured for both recombinant OBP and CSP.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
PDF
