Novel diterpenoids and hydrocarbons in the Dufour gland of the ectoparasitoid Habrobracon hebetor (Say) (Hymenoptera: Braconidae)

Chemical constituents contained in the Dufour gland of the ectoparasitoid Habrobracon hebetor (Say) (Hymenoptera: Braconidae) were characterized. Three terpenes, beta-springene, a homo-beta-springene, and a homo-geranyllinalool constitute approximately 37% of the gland components, with the remaining 63% all being hydrocarbons. The hydrocarbons consist of a homologous series of n-alkanes (n-C21 to n-C31), a trace amount of 3-methyl C23, a homologous series of internally methyl-branched alkanes (11-methyl C23 to 13-methyl C35), one dimethylalkane (13,17-dimethyl C33), a homologous series of monoenes (C(25:1) to C(37:1)) with the double bonds located at Delta9, Delta13 and Delta15 for alkenes of carbon number 25 to 31 and at Delta13 and Delta15 for carbon numbers 33 to 37 and three homologous dienes in very low amounts with carbon numbers of 31, 32, and 33. The terpenoid and hydrocarbon composition of the Dufour gland was similar in virgin and mated females. However, in contrast to the hydrocarbons, the amount of beta-springene and homo-geranyllinalool increased significantly with time after adult emergence from the cocoon. Although many hydrocarbons in the Dufour gland are the same as those on the cuticle of this species [Howard and Baker, Arch. Insect Biochem. Physiol. 53:1-18 (2003)], substantial differences also occur. Of particular note is the chain length of alkenes and location of the double bonds: cuticular alkenes have a chain length of C23 to C29 and double bond locations at Delta5, Delta7, and Delta9, whereas the Dufour gland alkenes contains a greater range of carbon numbers and have no Delta5 or Delta7 alkenes. The Dufour gland contains only one of the long-chain dimethylalkanes found on the cuticle. Also, no terpenoids are found on the cuticle, and the Dufour gland contains none of the secondary wax esters that are major components on the cuticle. GC-MS analysis of lipids carried in the hemolymph of H. hebetor indicated that all hydrocarbons found on both the cuticle and in the Dufour gland are present, as are some of the wax esters. However, none of the terpenoids were detected in the hemolymph. This suggests that the hydrocarbons are synthesized in other tissues or cells, probably by oenocytes, and differentially partitioned between the cuticle and the Dufour gland. The terpenoids are most likely synthesized within the Dufour gland. Analysis of surface lipids from eggs laid within 18 h indicated that no diterpenoids were present. Rather, the lipids present on the eggs were n-alkanes, monomethylalkanes, alkenes, and secondary alcohol wax esters. This composition did not reflect that of the Dufour gland, hence eggs are not being coated with Dufour gland components during oviposition.     

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

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

Morphology and chemistry of Dufour glands in four ectoparasitoids: Cephalonomia tarsalis,C. waterstoni (Hymenoptera: Bethylidae), Anisopteromalus calandrae,and Pteromalus cerealellae (Hymenoptera: Pteromalidae)

The venom apparatus of four hymenopterous parasitoids, including two bethylids, C. tarsalis (Ashmead) and C. waterstoni (Gahan), and two pteromalids, A. calandrae (Howard) and P. cerealellae (Ashmead), were removed and the associated Dufour glands characterized with respect to their external morphology and chemistry. Dufour glands in all four species have a characteristic translucent appearance that apparently results from their lipid content. The stalked Dufour glands of C. tarsalis and C. waterstoni are pear-shaped and have overall lengths of approximately 0.2 and 0.15 mm, respectively. The thin venom glands are bifurcate and insert through a fine duct into the transparent ovoid- to pear-shaped venom reservoir in these bethylids. In A. calandrae and P. cerealellae the Dufour glands are elongated, tubular structures of ca. 0.35 and 0.8 mm in length, respectively, that constrict to a short stalk that empties into the common oviduct. The venom glands in these pteromalids are simple elongated structures that insert into the sac-like venom reservoir through a fine duct. The chemistry of the volatile contents of the Dufour gland in these four species differs considerably. C. tarsalis Dufour glands contain the same hydrocarbon components as found on the cuticle of this species (Ann. Entomol. Soc. Am. 91:101-112 (1998)), and no other chemicals. The Dufour glands of C. waterstoni also contain only hydrocarbons, most of which are the same as the cuticular hydrocarbons (Ann. Entomol. Soc. Am. 85:317-325 (1992)), but in addition the Dufour gland contains ca. 3% of a mixture of 2,17- and 2,19-dimethyl C(23). A. calandrae Dufour gland chemistry is somewhat more complex than that of either of the two bethylids, but like the bethylids, only hydrocarbons are present. The carbon number range is from C(30) to C(39) and consists of a mixture of n-alkanes (C(30)-C(38)); 3-, 5-, 7-, 9-, 11-, 12-, 13-, 14-, 15- and 17-methyl alkanes; 3,7- and 3,11-dimethyl alkanes; 5,9- and 5,17-dimethyl alkanes; 7,11-, 9,13-, 13,17-, 14,18- and 15,19-dimethyl alkanes; 3,7,11- and 3, 9,15-trimethyl alkanes; and 3,7,11,15-tetramethyl alkanes. The cuticular hydrocarbons of this species have not been previously reported, but they are the same as the Dufour gland hydrocarbons. The Dufour glands of P. cerealellae contain both hydrocarbons and two long-chain aldehydes. Most of the hydrocarbons are identical to those found on the cuticle of this species (Ann. Entomol. Soc. Am. 94:152-158 (2001)), but in addition, 5,9-dimethyl C(27), 5,13-, 5,17- and 5,19-dimethyl C(35), 12- and 14-methyl C(36), 12,16- and 13,17-dimethyl C(36), 13-methyl C(37) and 13,17-dimethyl C(37) are present. The two aldehydes detected in glands from P. cerealellae are n-tetracosanal (C(23)CHO) and n-hexacosanal (C(25)CHO).     

Egg marking in the facultatively queenless ant Gnamptogenys striatula: the source and mechanism

Conflicts over reproductive division of labour are common in social insects. These conflicts are often resolved via antagonistic actions that are mediated by chemical cues. Dominant egg layers and their eggs can be recognized by a specific yet similar cuticular hydrocarbon profile. In the facultatively queenless ant Gnamptogenys striatula, a worker's cuticular hydrocarbon profile signals its fertility and this determines its position in the reproductive division of labour. How eggs acquire the same hydrocarbon profile is as yet unclear. Here, we search for glandular sources of egg hydrocarbons and identify the putative mechanism of egg marking. We found that eggs carry the same hydrocarbons as the cuticle of fertile workers, and that these hydrocarbons also occur in the ovaries and the haemolymph. None of the studied glands (Dufour, venom, labial and mandibular gland) contained these hydrocarbons. Our results indicate that hydrocarbons are deposited on eggs while still in the ovaries. The low hydrocarbon concentration in the ovaries, however, suggests they are produced elsewhere and transported through the haemolymph. We also found that fertile workers regularly deposit new hydrocarbons on eggs by rubbing laid eggs with a hairy structure on the abdominal tip from which a non-polar substance is secreted.     

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

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

Dufour gland of the digger wasp<Emphasis Type="Italic"> Liris niger:</Emphasis> structure and developmental and biochemical aspects

The tubiform Dufour gland in the digger wasp species Liris niger is about 1.0 mm long ( 0.15 mm). An alternating arrangement of longitudinal and circumferential bundles of striated muscle fibers surrounds the gland. The Dufour gland, together with the venom gland, enters the sting base and terminates in the sting. The glandular epithelium is monolayered. Glands about 3 day after imaginal ecdysis have an empty lumen but a thick lining epithelium. The gland cells are characterized by a well-developed vesicular smooth endoplasmic reticulum, sparse rough ER and numerous free ribosomes. They also exhibit several electron-lucent vesicles and autophagic vacuoles. Secretion of electron-dense material via the gland cuticle into the gland lumen is apparent. Glands more than 20 days after imaginal ecdysis display a large lumen and a thin epithelium. The cells show signs of degeneration with numerous cytolytic inclusions. Dufour gland liquid contains numerous polypeptides of molecular weights ranging from 14 to about 200 kDa. In addition the secretion consists predominantly of straight-chain hydrocarbons, accompanied by small amounts of esters. The major hydrocarbons are pentadecane and (Z)-8-heptadecene. Dufour gland secretion may have several functions: (1) the polypeptides might be involved in the gluing process of the eggs, while (2) the hydrocarbon oils may function as lubricants for the lancets and (3) might soften the secretion, thus allowing easier application of the glue. The lipophilic volatile material (4) might also be involved in pheromonal signaling.     

Dufour gland secretions of Myrmica rugulosa and Myrmica schencki workers

The chemical composition and behavioural activities of the secretions of the Dufour glands of Myrmica rugulosa and M. schencki have been studied, as part of an extended study on Myrmica ants. Chemically, the Dufour gland of M. rugulosa is filled with a mixture of hydrocarbons dominated by straight chain alkanes and alkenes with 13 to 19 carbon atoms, as found in M. rubra. Significant quantities of (Z,E)-α-farnesene and its homologues, homofarnesene and bishomofarnesene, are also present. In M. schencki, the major compounds present are homofarnesene and bishomofarnesene. In both species, the very volatile portion of the Dufour gland secretion is identical to that analysed in M. rubra. From an ethological point of view, this very volatile part is efficient in attracting workers at a distance (6 to 8 cm) and in decreasing their wandering movements. No specificity was observed when performing cross-tests with Dufour glands freshly isolated from workers of other Myrmica species, but obvious specificities were detected when testing the less volatile part of the Dufour glands' contents, known to be used for marking newly discovered areas.     

Correlation between mandibular gland secretion and cuticular hydrocarbons in the stingless bee Melipona quadrifasciata

We investigated whether Melipona quadrifasciata worker mandibular gland secretions contribute directly to their cuticular hydrocarbon profile. The mandibular gland secretion composition and cuticular surface compounds of newly emerged worker bees, nurse bees, and foragers were determined by gas chromatography and mass spectrometry and compared. Both the mandibular gland secretions and the cuticular surface compounds of all worker stages were found to be composed almost exclusively of hydrocarbons. Although the relative proportion of hydrocarbons from the cuticular surface and gland secretion was statistically different, there was a high similarity in the qualitative composition between these structures in all groups of bees.     

Task-related variation of postpharyngeal and cuticular hydrocarbon compositions in the ant Myrmicaria eumenoides

In the ant Myrmicaria eumenoides we investigated postpharyngeal and cuticular hydrocarbons. At eclosion the glands contained almost no hydrocarbons and there were no lipid inclusions in the glandular epithelium. During the first 3 weeks of adult life the amount of hydrocarbons in the gland increased until day 5, and then remained constant while the lipid content in the epithelium increased steadily. Intracolonial hydrocarbon compositions were not uniform. Compositions of post-pharyngeal and cuticular hydrocarbons in individual ants varied simultaneously, but in different manner depending on the tasks of the ant (brood-tenders, foragers, scouts). Variations on the cuticle were greater than in the gland, but they were strongly correlated. Independent of ants' age and task, cuticular hydrocarbon compositions were dominated by alkenes and alkadienes. Task-specific differences in cuticular compositions were mainly in the amount of alkenes (high in foragers) and alkadienes (high in brood-tenders). Variation of hydrocarbons was low in ants up to 10 weeks old. Thereafter, ants fell into two groups: (1) ants that did not change their hydrocarbons and remained in the nest, and (2) ants that changed their hydrocarbon compositions and became foragers. These results contribute to an ongoing discussion of the dynamic relationship between post-pharyngeal and cuticular hydrocarbons.     

Methyl-branched hydrocarbons, major components of the waxy material coating the embryos of the viviparous cockroach Diploptera punctata

The viviparous cockroach Diploptera punctata carries a wax-coated batch of embryos in a brood sac. When the embryos are expelled into saline, flakes of wax from the surface of the embryos float to the surface. In contrast, embryos of the ovoviviparous species such as Rhyparobia maderae are not nourished by the mother during embryogenesis and do not have a copious waxy coating. As a first step in determining the function of this copious wax layer on the batch of embryos of D. punctata, its composition was compared to that of the waxy material on the outer cuticular surface of the mother (female cuticle) by thin-layer chromatography (TLC) and gas chromatography-mass spectrometry. The major lipid class on the embryos was hydrocarbons with lesser amounts of wax esters and long-chain alcohols. Hydrocarbons from both sources had similar elution times and chemical composition, but were markedly different in the amounts of the major methyl-branched hydrocarbon components. A mixture of 3,X-dimethyl alkanes were 44% of the hydrocarbons on the embryos and were only 29% on the female cuticle. However, trimethylalkanes were only 22% of the hydrocarbons on the embryos and were 34% of the hydrocarbons on the female cuticle. The major hydrocarbons from both sources were mixtures of methyl-branched alkanes with backbones of 33 and 35 carbon atoms. Methyl-branched tritriacontanes were 59% of embryo and 35% of female cuticular hydrocarbons; methyl-branched pentatriacontanes were 19% of embryo and 42% of female hydrocarbons. The difference in proportions of the similar hydrocarbons on the outer cuticular surface of the female and those covering the embryos may suggest that the evolution of copious nutrient secretion for the embryos was accompanied by selection for a mixture of hydrocarbons that prevents water loss by the embryos and protects them against invasion by microorganisms without preventing the movement of nutrient fluid into the embryos.     

Not only cuticular lipids: first evidence of differences between foundresses and their daughters in polar substances in the paper wasp Polistes dominulus

Several studies have shown that differences in the relative abundance of cuticular hydrocarbons occur between reproductives and non-reproductives in many social insects. These differences also exist between Polistes dominulus foundresses and their first emerged daughters (usually indicated as workers), but they gradually disappear when workers from orphaned colonies develop their ovaries and assume a reproductive role in the colony. However, hydrocarbons are not the exclusive components of cuticular layer of wasps. Mass-spectrometry analysis of cuticular methanol extracts from Polistes paper wasps showed a complex pattern of polar substances, partly or totally proteinaceous in nature. We found that these compounds, ranging from 918 to 2679 Da, showed a clear caste differentiation between foundresses and their first emerged daughters (usually indicated as "workers"), both in queen-right and in orphaned colonies. Conversely to hydrocarbons, workers from orphaned colonies maintain a significant difference from foundresses in the pattern of the medium molecular weight (MW) polar compounds obtained by MALDI-TOF. On the basis of such results we hypothesize that a reliable cue to identify foundresses from daughters, and not only their reproductive status, may exist in Polistes wasps. Although the great majority of previous work on social insect communication has focused on cuticular hydrocarbons, our findings suggest that the medium MW component of cuticular substances may be involved in recognition.     

The subepithelial gland in ants: a novel exocrine gland closely associated with the cuticle surface

Two glandular systems were discovered that secrete their products onto the cuticular surface in ants. The first, the subepithelial gland, was previously undescribed in ants, and is found throughout the body just beneath the epithelium. This gland consists of independent secretory units, each made up of a single gland cell and an associated duct cell that penetrates the cuticle. Its ultrastructural appearance is consistent with possible hydrocarbon production. Examining 84 ant species, the subepithelial gland was found in eight subfamilies (out of 13), although not necessarily in all species. In a single ant species, Harpegnathos saltator, it was the epithelium itself that was enlarged and functioned as a gland. The enlarged epithelial cells secrete their products directly onto the cuticle through distinct cuticular crevasses.     

Comparative study of the dufour gland secretions of workers of four species of Myrmica ants

The Dufour gland secretions of myrmica rubra, M. ruginodis, M. sabuleti and M. scabrinodis have been studied. The most volatile portions of the secretion of workers of all four species were found to be similar, containing C₂C₄ oxygenated compounds. The less volatile portion consists of a mixture of hydrocarbons. In M. ruginodis this is chiefly a mixture of linear saturated and mono-unsaturated hydrocarbons, similar in composition to that of M. rubra, while in M. sabuleti it consists of (Z,E)-α-farnesene and its homologues, homofarnesene, bishomofarnesene and trishomofarnesene, similar in composition to that of M. scabrinodis. Workers of each species studied were attracted to the Dufour gland volatiles of all four species, these substances chiefly causing an increase in running speed, with the workers not distinguishing between conspecific and allospecific secretions, though small quantitative differences could be demonstrated between the speed and orientation reaction of workers of each species. The less volatile fraction of the Dufour gland secretion is used for territorial marking by foraging workers. This marking is specific for each species except between M. rubra and M. ruginodis.     

Cuticular hydrocarbons,social organization and ovarian development in a polistine wasp: Polistes dominulus christ

• 1.1. The cuticular hydrocarbons of the wasp, Polistes dominulus, are linear branched, saturated alkanes, mainly monomethylalkanes.
• 2.2. The foundress can be distinguished from her offspring by differences in the relative proportions of some alkanes and monomethylalkanes, which were the same in all the foundresses studied here. The ovarian state is linked to the cuticular spectrum since these constituents were present in similar proportions in a foundress and in a descendant with comparably developed ovaries.
• 3.3. In some, but not all cases, it was possible to discriminate between descendants originating from different foundresses on the basis of other hydrocarbons belonging to all the chemical families present.
• 4.4. No correlations were observed between the descendants' behavioural profiles and the cuticular hydrocarbon spectra.

     

Development of the retinotectal system in the direct-developing frog Eleutherodactylus coqui in comparison with other anurans

Background

Associations between animal species require that at least one of the species recognizes its partner. Parabioses are associations of two ant species which co-inhabit the same nest. Ants usually possess an elaborate nestmate recognition system, which is based on cuticular hydrocarbons and allows them to distinguish nestmates from non-nestmates through quantitative or qualitative differences in the hydrocarbon composition. Hence, living in a parabiotic association probably necessitates changes of the nestmate recognition system in both species, since heterospecific ants have to be accepted as nestmates.

Results

In the present study we report highly unusual cuticular profiles in the parabiotic species Crematogaster modiglianii and Camponotus rufifemur from the tropical rainforest of Borneo. The cuticle of both species is covered by a set of steroids, which are highly unusual surface compounds. They also occur in the Dufour gland of Crematogaster modiglianii in high quantities. The composition of these steroids differed between colonies but was highly similar among the two species of a parabiotic nest. In contrast, hydrocarbon composition of Cr. modiglianii and Ca. rufifemur differed strongly and only overlapped in three regularly occurring and three trace compounds. The hydrocarbon profile of Camponotus rufifemur consisted almost exclusively of methyl-branched alkenes of unusually high chain lengths (up to C₄₉). This species occurred in two sympatric, chemically distinct varieties with almost no hydrocarbons in common. Cr. modiglianii discriminated between these two varieties. It only tolerated workers of the Ca. rufifemur variety it was associated with, but attacked the respective others. However, Cr. modiglianii did not distinguish its own Ca. rufifemur partner from allocolonial Ca. rufifemur workers of the same variety.

Conclusion

We conclude that there is a mutual substance transfer between Cr. modiglianii and Ca. rufifemur. Ca. rufifemur actively or passively acquires cuticular steroids from its Cr. modiglianii partner, while the latter acquires at least two cuticular hydrocarbons from Ca. rufifemur. The cuticular substances of both species are highly unusual regarding both substance classes and chain lengths, which may cause the apparent inability of Cr. modiglianii to discriminate Ca. rufifemur nestmates from allocolonial Ca. rufifemur workers of the same chemical variety.     

Identification of cuticular hydrocarbons and the alkene precursor to the pheromone in hemolymph of the female gypsy moth, Lymantria dispar

Hydrocarbons were extracted from the surface of the cuticle and from the hemolymph of adult female gypsy moths. GC and GC/MS analysis indicated that the cuticular hydrocarbons with chain lengths >21 carbons were the same as those found in the hemolymph. These consisted of mostly saturated straight chain hydrocarbons with heptacosane the major component. Methyl branched hydrocarbons were also identified including a series of tetramethylalkanes with chain lengths of 30, 32, and 34 carbons. In addition to those found on the cuticle surface, the hemolymph contained the alkene pheromone precursor, 2-methyl-Z7-octadecene and two saturated analogues, 2-methyl-octadecane and 2-methyl-hexadecane. No evidence was obtained for the presence of the pheromone 2-methyl-7, 8-epoxy-octadecane in the hemolymph. Pheromone gland extracts indicated that small amounts (<1 ng) of the alkene precursor were also present in the gland. Relatively larger amounts of the alkene precursor were found in the hemolymph at the time when pheromone titers were higher on the gland. The presence of the hydrocarbon pheromone precursor in the hemolymph is discussed in relation to possible biosynthetic pathways for producing the gypsy moth pheromone.     

Hydrocarbon circulation and colonial signature in Pachycondyla villosa

In ants, both cuticular and postpharyngeal gland (PPG) hydrocarbons (HCs) have been involved in nestmate recognition. However, no detailed comparison is available. A comparative study including also high density lipophorin (HDLp), an internal HC carrier, was therefore undertaken on Pachycondyla villosa. Purified HDLp is an 820 kDa lipoprotein with a density of 1.114 g/ml and two 245 and 80 kDa apo-proteins. Its hydrocarbon profile is very similar with the cuticular one, in agreement with its hydrocarbon carrier function. Conversely, n-alkanes and externally branched monomethylalkanes are markedly decreased in the PPG. According to their physical properties, this suggests that they are involved in waterproofing on the cuticle. The PPG actually contains only internally branched mono-, dimethylalkanes or monomethylalkenes; their greater fluidity is more adequate for chemical communication. The percentages of some of them are statistically not different between the cuticle and PPG. Their mixtures vary with colonies and they may thus be involved in colonial signature. A scheme for hydrocarbon circulation is discussed, involving lipophorin, cuticle, PPG and self-grooming in one individual, a pathway complementary or alternative to the selective delivery by lipophorin in some other insects. HCs are then distributed between nestmates' cuticles through allo-grooming and physical contacts.     

Variation in cuticular hydrocarbon signatures, hormonal correlates and establishment of reproductive dominance in a polistine wasp

In many social insects the relationship between reproductive dominance and physiological correlates is poorly understood. Recent evidence now strongly suggests that cuticular hydrocarbons are important in reproductive differentiation in these societies where they are used as signals of ovarian activity in reproductive females. In this study we investigated the relationship between reproductive dominance, size of the corpora allata (CA, producer of Juvenile Hormone, JH) and the proportions of cuticular hydrocarbons present on the cuticle in overwintering foundresses and both associative (polygynous) and solitary (monogynous) pre-emergence colonies of the social wasp Polistes dominulus. Size of the CA was positively correlated with ovarian development in polygynous colonies. In contrast, solitary foundresses possessed significantly smaller CAs than dominant foundresses from polygynous nests, yet ovarian activity was similar for both female types. CA size variation was associated with variation in cuticular hydrocarbon proportions. Overwintering, solitary, dominant and subordinate (from associative nests) females all possessed distinctive cuticular chemical profiles revealed by multivariate discriminant analyses. Our data indicate that the social environment strongly affects reproductive physiology in this wasp, and we discuss the role of cuticular hydrocarbons in reproductive signaling in P. dominulus and other social insects.     

Crickets detect the genetic similarity of mating partners via cuticular hydrocarbons

Animals should decipher information about the genetic make‐up of conspecifics in order to enhance the fitness benefits associated with mate choice. Although there is increasing evidence to suggest that animals make genetically informed decisions about their mating partners, we understand relatively little about the sensory mechanisms informing these decisions. Here, we investigate whether cuticular hydrocarbons, chemical compounds found on the cuticle of most terrestrial arthropods, provide a means of discerning genetic similarity during mate choice in the cricket, Teleogryllus oceanicus. We found that individuals preferentially mated with partners who share more dissimilar cuticular hydrocarbon profiles and that similarity in cuticular hydrocarbon profiles between mating pairs correlated with their genetic similarity. Our results provide good evidence that cuticular hydrocarbon profiles offer a means of assessing genetic compatibility in T. oceanicus, enabling individuals to choose their most genetically suitable mate.     

Nest Hydrocarbons as Cues for Philopatry in a Paper Wasp

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.