Papers by Stefano Turillazzi
Sex can be a difficult task for motionless dispersed organisms such as the yeast Saccharomyces ce... more Sex can be a difficult task for motionless dispersed organisms such as the yeast Saccharomyces cerevisiae. Albeit yeasts are known to mainly asexually reproduce in nature, they should rely on sex to generate new genetic assemblies. Recent studies on the worldwide S. cerevisiae wild biodiversity significantly broadened the yeast population genetics horizons. Nevertheless, indication on where the yeast sexual reproduction can occur is still lacking. Social insects, by vectoring and maintaining yeast cells in the wild and among different environments, guarantee a possible site for yeasts meeting and mating. S. cerevisiae strains isolated from the intestines of social insects show higher heterozygosis than any other wild and human-related isolate, indicating an occurred genome mixing of different yeast lineages. We provide experimental evidence that Saccharomyces sensu stricto strains co-habiting the intestines of social insects can face sexual reproduction, generating inter-and intra-specific hybrids. This indication, rising from the identification and whole-genome sequencing of S. cerevisiae X S. paradoxus and S. cerevisiae X S. bayanus hybrids isolated from the wild V. crabroguts, is mirrored by results obtained in in vitro conditions (Polistes spp. and Apis mellifera). The intestine of social insects is identified as the niche where Saccharomyces spp. can meet and mate, finally acting as yeasts mating nest and contributing in shaping the fungal evolutionary ecology.
Journal of Chemical Ecology, May 22, 2018
Social wasps encompass species displaying diverse social organization regarding colony cycle, nes... more Social wasps encompass species displaying diverse social organization regarding colony cycle, nest foundation, caste differences (from none to significant dimorphism) and number of reproductive queens. Current phylogenetic data suggests that sociality occured independently in the subfamily Stenogastrinae and in the Polistinae+Vespinae clade. In most species, including those with the simplest social organization, colony reproduction is monopolised by a single or few females. Since their nest mates can also develop ovaries and lay eggs, dominant females must somehow inhibit them from reproducing. Physical interactions in the form of open aggression or, usually, ritualised dominance by the fertile females contribute to fertility inhibition in several species, but it is unlikely to function in large colonies. In the latter case, reproduction within the colony is likely to be regulated through pheromones. Relatively little is known about these semiochemicals. Studies on all the three social wasp subfamilies, revealed that cuticular hydrocarbon components differ in abundance between egg-laying and not egg-laying females and that their composition depends on fertility status. In several species, females have been reported to manifestly react towards females with activated ovaries, but there is little evidence to support the hypothesis that fertile individuals are either recognized through their CHC composition, or that over-represented CHC constituents can inhibit fertility. Moreover, very little information exists on the possibility that exocrine glands release fertility signals or chemicals inhibiting fertility. Keywords Reproduction partitioning. Queen pheromone. Oophagy. Cuticular hydrocarbons. Dufour gland. Social parasites Social wasps comprise a broad group of genera and species with very diverse social organizations, colony size and colony cycle. Since the first comprehensive review on pheromones and chemical communication in social wasps (Downing 1991), only a limited number of studies have investigated volatiles from exocrine glands and their role in communication (Bruschini et al. 2010). On the contrary, several researches have considered the role of cuticular hydrocarbons (CHCs) as recognition pheromones in different social contexts (Dani 2006; Kather and Martin 2015; Lorenzi 2006). The literature on CHCs in the context of dominance hierarchies in females of Polistes species has recently been reviewed (Jandt et al. 2014). Here we analyze the current knowledge on chemical communication in reproductive partitioning in social wasps and discuss the limits of the current state of art, addressing possible directions for future research.
Behavioral Ecology and Sociobiology, Feb 29, 2008
A challenge for parasites is how to evade the sophisticated detection and rejection abilities of ... more A challenge for parasites is how to evade the sophisticated detection and rejection abilities of potential hosts. Many studies have shown how insect social parasites overcome host recognition systems and successfully enter host colonies. However, once a social parasite has successfully usurped an alien nest, its brood still face the challenge of avoiding host recognition. How immature stages of parasites fool the hosts has been little studied in social insects, though this has been deeply investigated in birds. We look at how larvae of the paper wasp obligate social parasite Polistes sulcifer fool their hosts. We focus on cuticular hydrocarbons (CHCs), which are keys for adult recognition, and use behavioral recognition assays. Parasite larvae might camouflage themselves either by underproducing CHCs (odorless hypothesis) or by acquiring a chemical profile that matches that of their hosts. GC/MS analyses show that parasite larvae do not have lower levels of CHCs and that their CHCs profile is similar to the host larval profile but shows a reduced colony specificity. Behavioral tests show that the hosts discriminate against alien conspecific larvae from different colonies but are more tolerant towards parasite larvae. Our results demonstrate that parasite larvae have evolved a host larval profile, which overcomes the host colony recognition system probably because of the lower proportion of branched compounds compared to host larvae. In some ways, this is a similar hypothesis to the odorless hypothesis, but it assumes that the parasite larvae are covered by a chemical blend that is not meaningful to the host.
Ethology Ecology & Evolution, 2003
... Journal of Insect Physiology 46: 753-761. WHEELER JW, AYORINDE FO, GREENE A. &amp... more ... Journal of Insect Physiology 46: 753-761. WHEELER JW, AYORINDE FO, GREENE A. & DUFFIELD RM 1982. Citronellyl citronellate and citronellyl geranate in the European hornet, Vespa crabro (Hymenoptera: Vespidae). Tetrahedron Letters 23: 2071-2072. ZAR JH 1996. ...
Journal of Insect Physiology, Sep 1, 2007
Social insects use cuticular hydrocarbons (CHCs) as recognition cues in a variety of social conte... more Social insects use cuticular hydrocarbons (CHCs) as recognition cues in a variety of social contexts, such as species and nestmate recognition. Discrimination of nestmates is an important requisite to avoid exploitation by unrelated individuals. In social wasps, use of CHCs in nestmate recognition has been demonstrated only among adults, whereas very little is known regarding brood recognition. We performed gas chromatography-mass spectrometry analyses of the CHCs of adults and larvae of the social wasp Polistes dominulus and found that larvae possess a characteristic chemical colony-specific pattern distinct from that of adults. Behavioural assays confirmed that these are recognized and discriminated by adults. Larval epicuticular substances are therefore sufficient for recognition of nestmate larvae by adults and demonstrate that wasps are able to discriminate between alien and nestmate larval odours.
Behavioural Processes, Dec 1, 1992
The behaviour of stroking the abdomen over the nest surface has previously been described in fema... more The behaviour of stroking the abdomen over the nest surface has previously been described in females of only a few Polistes wasp species, and was considered to be associated with pheromonal release. This study examines abdomen stroking in solitary and multiple female laboratory colonies of Polistes dominulus during the pre-emergence period. In multiple female colonies stroking behaviour is related to hierarchy: alpha females stroking more than subordinates. However, after removal of the dominant female the subordinate increases her stroking rate. Solitary females also stroke but, unlike alpha females, they do so less during the egg-stage than in subsequent stages of the colonial cycle. It is hypothesized that abdomen stroking cues the immature brood as to which adult female is the dominant individual; this could lead to competition between females on the same nest. This function is also discussed in the context of intra- and inter-specific Polistes parasites, where the behaviour is particularly evident.
Chemical Senses, Jul 21, 2007
Differences in long-chain hydrocarbon mixtures among reproductive and nonreproductive individuals... more Differences in long-chain hydrocarbon mixtures among reproductive and nonreproductive individuals have been often revealed in social insects. However, very few papers demonstrated that these signatures actually act as contact pheromones used by nonreproductive to recognize the presence of a related queen in the colony. Cuticular and glandular hydrocarbons of Polistes paper wasps have been extensively studied, but, until now, the perception and recognition of such cues was not demonstrated. In this paper, we show, for the first time in Vespidae, that Polistes gallicus workers distinguish nestmates from alien individuals and queens from workers by the hydrocarbon mixtures of the Van der Vecht organ secretion (VVS). We also demonstrated that stroking behavior (a peculiar behavior of Polistes by which queens probably lay VVS on the nest) acts as an inhibitor of ovarian development in workers.
Chemical Senses, May 25, 2005
In social insects, recognition of nestmates from aliens is based on olfactory cues, and many stud... more In social insects, recognition of nestmates from aliens is based on olfactory cues, and many studies have demonstrated that such cues are contained within the lipid layer covering the insect cuticle. These lipids are usually a complex mixture of tens of compounds in which aliphatic hydrocarbons are generally the major components. The experiments described here tested whether artificial changes in the cuticular profile through supplementation of naturally occurring alkanes and alkenes in honeybees affect the behaviour of nestmate guards. Compounds were applied to live foragers in microgram quantities and the bees returned to their hive entrance where the behaviour of the guard bees was observed. In this fashion we compared the effect of single alkenes with that of single alkanes; the effect of mixtures of alkenes versus that of mixtures of alkanes and the whole alkane fraction separated from the cuticular lipids versus the alkene fraction. With only one exception (the comparison between n-C 19 and (Z)9-C 19), in all the experiments bees treated with alkenes were attacked more intensively than bees treated with alkanes. This leads us to conclude that modification of the natural chemical profile with the two different classes of compounds has a different effect on acceptance and suggests that this may correspond to a differential importance in the recognition signature.
Physiological Entomology, Jul 7, 2008
The contents of the venom sacs of the two epiponine species Polybia occidentalis (Olivier) and P.... more The contents of the venom sacs of the two epiponine species Polybia occidentalis (Olivier) and P. sericea (Olivier) (Hymenoptera: Vespidae) have been analysed by GC-MS for their volatile constituents. The mixture of volatiles was found to be very diverse in both the species. The spiroacetal (E,E)-2,8-dimethyl-1,7-dioxaspiro[5.5]undecane, was present in both species and was the major component in P. occidentalis, where it was determined to show (2S,6R,8S)-con®guration. An enantiomerically pure synthetic sample was tested in ®eld bioassays on P. occidentalis colonies and was clearly shown to elicit alarm behaviour.
Insectes Sociaux, Dec 26, 2017
In recent years, a number of studies have suggested that visual status signaling operates in soci... more 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.
Journal of Insect Physiology, Jun 1, 1996
The Dufour gland secretion and cuticle lipids of foundresses of Polistes dominulus have been chem... more The Dufour gland secretion and cuticle lipids of foundresses of Polistes dominulus have been chemically analysed. The gland secretion (analysed for the first time in a polistine species) contains a complex mixture of hydrocarbons, which are the same as those found on the cuticle. The cuticular hydrocarbon mixture and gland secretion differ, however, in the proportions of components: in the first, linear hydrocarbons are more abundant, while in the second we found a higher quantity of dimethylalkanes. Multivariate statistical analysis has shown that foundresses belonging to different colonies are distinguished on the basis of both the composition of their Dufour gland secretion and cuticular hydrocarbon mixture. Branched hydrocarbons seem to be particularly important in distinguishing females according to their colony. We suggest that the Dufour gland may contribute substances to form the hydrocarbon layer on the cuticle.
Behavioral Ecology and Sociobiology, Nov 18, 1996
The capacity to recognise a conspecific intruder was investigated in Parischnogaster jacobsoni, L... more The capacity to recognise a conspecific intruder was investigated in Parischnogaster jacobsoni, Liostenogaster flavolineata and L. vechti, three species of primitively social wasps of the subfamily Stenogastrinae. Results of behavioural experiments carried out in the field showed that females of all three species react pacifically if presented with female nestmates, but aggressively reject an intruder from a conspecific colony. As L. flavolineata and L. vechti both build large clusters of nests, often very close to each other, the recognition capacity among females from different nests, but in the same conspecific cluster, was also investigated. Females of both species were more aggressive towards females from a different colony in the same cluster than towards their female nestmates. Additional experiments on L. flavolineata showed that there was no difference in reaction towards females from colonies nearer or further from the tested colony but within the same cluster, nor towards females from a different cluster. The capacity to recognise an alien conspecific nest containing immature brood was investigated in P. jacobsoni. Adult females of this species, invited to land on an alien nest which had experimentally been exchanged for their own, accepted the new nest and partially destroyed the immature brood. The behaviour of the females when they land on an alien nest, however, suggests that they do recognise the nest as foreign. Acceptance of foreign nests coupled with low immature brood destruction is probably due to the high energetic costs of egg-deposition and larval rearing in stenogastrine wasps. These results suggest that nestmate recognition in these wasps is very efficient, even though they belong to the most primitive subfamily of social wasps.
Journal of Chemical Ecology, 1996
The long-chain carboxylic acids identified in the sternal gland secretion ofPolistes dominulus an... more The long-chain carboxylic acids identified in the sternal gland secretion ofPolistes dominulus andP. sulcifer females were tested individually on three species of ants,Crematogaster scutellaris, Formica cunicularia, andLasius sp., in order to verify if they have a repellent effect. The unsaturated acids (palmitoleic, linoleic, and oleic) act as repellents of all three ant species, while the saturated acids (lauric, myristic, palmitic, and stearic) have no effect. The mixture reproducing the secretion of the sternal glands ofP. dominulus maintained its repellency for at least four days.
Current Biology, Jul 1, 2007
Ethology Ecology & Evolution, Oct 1, 1997
... Fig. 1. — Three dimensional frequency distribution of various type of colonies in the bridge ... more ... Fig. 1. — Three dimensional frequency distribution of various type of colonies in the bridge cluster studied. The area represents the vault of the bridge divided into 25 rectangles. Page 4. 388 S. Turillazzi, R. Cervo and FR Dani ...
Naturwissenschaften, Sep 17, 2016
Sexual signals serve as an honest indicator of individual quality, reflecting either developmenta... more Sexual signals serve as an honest indicator of individual quality, reflecting either developmental and/or maintenance costs. A possible underlying physiological mechanism is oxidative stress, which could mediate energy trade-offs between sexual signals and other quality traits. In ectotherms, thermal performance acts as a key indicator of individual quality and influence signal intensity. We investigated how oxidative state is reflected in visual signals of lizards from different thermal habitats. According to our hypothesis, efficient thermoregulation requires different strategies in different thermal environments. In a habitat with predictable temperature changes, animals are less exposed to suboptimal temperature ranges and selection will, therefore, be stronger on the maximum oxidative damage at optimal body temperature. Contrarily, in a habitat with rather stochastic thermal shifts, individuals are often constricted by suboptimal thermal conditions, and oxidative damage can be limiting on a wide temperature range. We used Iberolacerta cyreni and Psammodromus algirus inhabiting stochastic and predictable thermal environments respectively. We examined two aspects of oxidative stress: the level of reactive oxygen metabolites at the preferred temperature (maximal ROM) and the temperature range in which animals produce at least 80% of the maximum level of reactive oxygen metabolites (effective ROM range). In I. cyreni, we found that duller coloration was related to a wider effective ROM range, while expression of coloration in P. algirus was negatively correlated with the maximal ROM. Our results suggest that different thermal constraints affect different aspects of oxidative damage which can indicate individual quality and are, therefore, represented in sexual ornaments.
Insectes Sociaux, Aug 1, 2004
Alarm pheromones, chemical substances produced by social insects to alert the colony to threat, a... more Alarm pheromones, chemical substances produced by social insects to alert the colony to threat, are the principal means by which colony defence is coordinated. We present the results of a study on alarm behaviour in 5 swarming species of wasps belonging to the genus Ropalidia. These species show a remarkably efficient strategy of alarm communication, including visual display and attack synchronization. We show that pheromones released from the venom gland play an important role in alarm recruitment in species belonging to the Ropalidia flavopicta group, but not in Ropalidia sumatrae. We analysed the contents of the venom reservoirs content of four of the studied species by gas chromatography-mass spectrometry. Glands were found to contain a complex mixture of volatile compounds as well as spiroacetals of higher molecular weight. Interestingly, despite all species producing similar chemical compounds from the venom gland, these were found to elicit alarm behaviour in only those species that build nest envelopes, suggesting a link between chemical release of alarm behaviour and the evolution of nest architecture in Ropalidia wasps.
Animal Behaviour, Oct 1, 2015
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Papers by Stefano Turillazzi