Cuticular Hydrocarbons and Aggression in the Termite Macrotermes Subhyalinus

Cuticular hydrocarbons are among the prime candidates for nestmate recognition in social insects. We analyzed the variation of cuticular hydrocarbons in the termite species M. subhyalinus in West Africa (Comoë National Park) on a small spatial scale (<1 km). We found considerable variation in the composition of cuticular hydrocarbons among colonies, with four distinct chemical phenotypes. Different phenotypes occurred within each of the four habitats. The difference between these phenotypes is primarily due to unsaturated compounds. A clear correlation between the difference of the hydrocarbon composition and the aggression between colonies was found. This correlation also holds in a multivariate analysis of genetic similarity (measured by AFLPs), morphometric distances (measured by Mahalanobis-distances), as well as geographic distances between colonies. In a more detailed analysis of the correlation between the composition of cuticular hydrocarbons and aggression, we found that no single compound is sufficient to explain variation in aggression between pairings of colonies. Thus, termites seem to use a bouquet of compounds. Multiple regression analysis suggested that many of these compounds are unsaturated hydrocarbons and, thus, may play a key role in colony recognition.     

Cuticular Hydrocarbon Composition Reflects Genetic Relationship Among Colonies of the Introduced Termite Reticulitermes santonensis Feytaud

Nestmate recognition plays a key role in kin selection to maintain colony integrity in social insects. Previous studies have demonstrated that nestmate recognition is dependent on detection of cuticular hydrocarbons. However, the absence of intraspecific aggression between some colonies of Isoptera and social Hymenoptera questions whether kin recognition must occur in social insects. The purpose of this study was to determine if cuticular hydrocarbon similarity and high genetic relatedness could explain the lack of intraspecific aggression among and within colonies of the introduced subterranean termite Reticulitermes santonensis. We performed both GC analysis of cuticular hydrocarbons and genotyping by using 10 DNA microsatellite loci on the same 10 workers from each of 14 parisian colonies. Multivariate analyses demonstrated correspondence between cuticular hydrocarbon patterns and genetic variation. By using a redundancy analysis combining chemical and genetic data, we found that a few hydrocarbons (mainly short vs. long chains; saturated vs. unsaturated alkanes) were associated with most genetic variation. We also found a strong positive correlation between chemical and genetic distances between colonies, thus providing evidence of a genetic basis for cuticular hydrocarbon variation. However, genetic distance did not account for all chemical variation, thus suggesting that some hydrocarbon variation was environmentally derived. Investigation at the intracolony level indicated that cuticular hydrocarbons did not depend on colony social structure. Based on our findings, we speculate that the absence of intraspecific aggression in R. santonensis may result from a loss of diversity in genetically derived recognition compounds in this species that presumably descended from R. flavipes populations imported from North America.     

Identification of Termite Species by the Hydrocarbons in their Feces

Blends of abundant cuticular hydrocarbons are species-specific for termites (Isoptera) and can be used to identify a given taxon without the diagnostic castes, soldiers or adults. We demonstrate that hydrocarbon extracts of termite fecal pellets from damaged wood can also be characterized and used to identify termites responsible for damage, even though termites are no longer present or easily recovered. In structures infested by drywood termites, it is common to find fecal pellets, but difficult to extract termites from the finished wood in service. Nine species belonging to two families (Kalotermitidae and Termopsidae) were examined to compare the hydrocarbon composition of termites and their fecal pellets. Diversity was extensive: at least one half of the amount of the hydrocarbons from Neotermes connexus, Incisitermes immigrans, Cryptotermes brevis, Cryptotermes cynocephalus, Procryptotermes corniceps, and Zootermopsis nevadensis nuttingi was olefins. Incisitermes minor and Pterotermes occidentis incorporated only small amounts of olefins in cuticular hydrocarbons; Marginitermes hubbardi had no detectable olefins. Hydrocarbons extracted from fecal pellets were qualitatively and quantitatively similar to cuticular extracts and can be used to determine the termite species responsible without the termites present.     

Correlation of Mitochondrial Haplotypes with Cuticular Hydrocarbon Phenotypes of Sympatric Reticulitermes Species from the Southeastern United States

Three sympatric Reticulitermes species have been identified in Georgia, USA, based on morphological characters from alates and soldiers: R. flavipes, R. virginicus, and R. hageni, but species identification at individual collection sites is often difficult because alate production is seasonal and soldiers comprise 1–3% of the colony. We therefore set up an experiment to determine if chemical phenotypes and mtDNA haplotypes can be used together to separate species of subterranean termites. Subterranean termites of the order Reticulitermes (Isoptera: Rhinotermitidae) were collected from 20 inspection ports across four soil provinces in Georgia. Each collection was identified to species using dichotomous keys. Two collections, HH11 and BH25, however, could not be unequivocally keyed to species and were classified as unknown. The mitochondrial cytochrome oxidase II (COII) gene was sequenced from individual members of each collection and the variation in cuticular hydrocarbon phenotypes from these same collections was characterized. The cuticular hydrocarbon and mtDNA phylogenetic analyses show agreement with both unknown collections falling out in a separate clade. Specimens from HH11 nad BH25 are different morphologically, chemically, and genetically from the three known sympatric species in Georgia. Our results suggest that these two collections may represent at least one new taxon in Reticulitermes. Furthermore, the association of cuticular hydrocarbon phenotypes and mtDNA haplotypes demonstrates that, when combined with morphological characters, they are useful in separating known species, determining new species, and understanding termite evolution.     

Cuticular hydrocarbons of dampwood termites,Zootermopsis: Intra- and intercolony variation and potential as taxonomic characters

Colonies ofZootermopsis were collected from the central Sierra Nevada and the Monterey Penninsula in California, and from southern Arizona. Cuticular hydrocarbons were identified by gas chromatography-mass spectrometry (GC-MS) and quantified by gas-liquid chromatography (GLC) for each caste of all colonies. Four consistent and distinct cuticular hydrocarbon patterns, or chemical phenotypes, were identified. Unique and abundant monomethyl- and dimethylalkanes, and ann-alkene provided easy separation of the various phenotypes. Significant differences in the proportions of the various components were found among castes within a colony and colonies within phenotypes from California. Differences in the hydrocarbon proportions for castes were not consistent between colonies. The current taxonomy of the genusZootermopsis recognizes three species. Our identification of four consistent, unique cuticular hydrocarbon phenotypes from the three described species should alert systematists and others to a major concern. If there are truly only three extant species, then the hypothesis that cuticular hydrocarbon profiles in this genus are species specific is not acceptable. Conversely, if cuticular hydrocarbon profiles are truly species specific, then there is at least one new, undescribed species ofZootermopsis.Isoptera: Termopsidae.     

DIET-MEDIATED INTER-COLONIAL AGGRESSION IN THE FORMOSAN SUBTERRANEAN TERMITE <Emphasis Type="Italic">Coptotermes formosanus</Emphasis>

In most social insects, intercolonial and interspecific aggression are expressions of territoriality. In termites, cuticular hydrocarbons (CHCs) have been extensively studied for their role in nestmate recognition and aggressive discrimination of nonnest-mates. More recently, molecular genetic techniques have made it possible to determine relatedness between colonies and to investigate the influence of genetics on aggression. In the Formosan subterranean termite, Coptotermes formosanus, however, the role of CHCs and genetic relatedness in inter-colony aggression has been ambiguous, suggesting the involvement of additional factors in nest-mate recognition. In this study we assess the range of aggression in this termite species and characterize the influence of genetic relatedness, CHC profiles and diet on aggression levels. We collected four colonies of C. formosanus, feeding either on bald cypress or birch, from three locations in Louisiana. Inter-colony aggression ranged from low to high. Differences in CHC profiles, as well as genetic distances between colonies determined by using microsatellite DNA markers, showed no significant correlation with aggression. However, termite diet (host tree) played a significant role in determining the level of aggression. Thus, two distantly related colonies, each feeding on different diets, showed high aggression that significantly diminished if they were fed on the same wood in the laboratory (spruce). Using headspace solid phase microextraction, we found three compounds from workers fed on birch that were absent in workers fed on spruce. Such diet-derived chemicals may be involved in the complex determination of nest-mate recognition in C. formosanus.     

Fine Tuning of Social Integration by Two Myrmecophiles of the Ponerine Army Ant, <Emphasis Type="Italic">Leptogenys distinguenda</Emphasis>

Myrmecophiles are animals that live in close association with ants and that frequently develop elaborate mechanisms to infiltrate their well-defended host societies. We compare the social integration strategies of two myrmecophilic species, the spider, Gamasomorpha maschwitzi, and the newly described silverfish, Malayatelura ponerophila gen. n. sp. n., into colonies of the ponerine army ant, Leptogenys distinguenda (Emery) (Hymenoptera: Formicidae). Both symbionts use chemical mimicry through adoption of host cuticular hydrocarbons. Exchange experiments between L. distinguenda and an undetermined Leptogenys species demonstrate that reduced aggression toward alien ants and increased social acceptance occurred with individuals of higher chemical similarity in their cuticular hydrocarbon profiles. We found striking differences in chemical and behavioral strategies between the two myrmecophiles. Spider cuticular hydrocarbon profiles were chemically less similar to the host than silverfish profiles were. Nevertheless, spiders received significantly fewer attacks from host ants and survived longer in laboratory colonies, whereas silverfish were treated with high aggression and were killed more frequently. When discovered and confronted by the host, silverfish tended to escape and were chased aggressively, whereas spiders remained in contact with the confronting host ant until aggression ceased. Thus, spiders relied less on chemical mimicry but were nevertheless accepted more frequently by the host on the basis of behavioral mechanisms. These findings give insights into the fine tuning of social integration mechanisms and show the significance of qualitative differences among strategies. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Intercaste,intercolony, and temporal variation in cuticular hydrocarbons ofCopotermes formosanus shiraki (Isoptera: Rhinotermitidae)

We characterized the variation in cuticular hydrocarbon mixtures between seven colonies of the Formosan subterranean termite,Coptotermes formosanus Shiraki, from the same population. We report differences between castes, between colonies, and within the population over time to assess seasonality. Colonies ofC. formosanus from Oahu, Hawaii, were sampled for 25 months. Each month, one sample each of 200 workers, 50 soldiers, nymphs, or alates from each colony was subjected to gas chromatography-mass spectrometry (GC-MS) analysis of the cuticular hydrocarbons. We resolved 39 individual peaks and identified 52 individual or isomeric mixtures of hydrocarbons. Onlyn-alkanes and methyl-branched alkanes occur; no olefins were found. Internally branched monomethylalkanes were the most abundant class of hydrocarbons, representing 45% to 50% of the total 9-;11-;13-Methyl-heptacosane accounted for over 30% of the total hydrocarbon for all castes. 2-Methyl- and 3-methylalkanes comprise approximately 30% of the total. Internally branched dimethylalkanes constitute 15% to 20% of the total cuticular hydrocarbon. Only one trimethylalkane, 13,15,17-trimethylnonacosane, was found in small amounts. The hydrocarbon mixtures of all four castes were similar. Quantitative differences in hydrocarbon mixtures among the castes were easily displayed using canonical discriminant analysis. Soldiers and workers are significantly different from one another and from nymphs and alates. Nineteen peaks are statistically significant between workers and soldiers. Nymphs and alates were not statistically different. We detected statistically significant quantitative differences between colonies in 18 peaks for workers and 12 peaks for soldiers. Each of the colonies ofC. formosanus can be separated from the others by the proportions of their hydrocarbon components. We detected statistically significant differences between months of the year for 12 peaks for workers and four peaks for soldiers; two peaks each for workers and soldiers showed distinct, seasonal trends. This seasonal shift in proportions of hydrocarbons correlates with the production of alates.     

Cuticular hydrocarbons and defensive compounds ofReticulitermes flavipes (Kollar) andR. santonensis (feytaud): Polymorphism and chemotaxonomy

Colonies ofReticulitermes flavipes andR. santonensis were collected from the southeastern United States (Georgia) and the southwest of France (Charente-maritime). Defensive compounds and cuticular hydrocarbons were identified by gas chromatography-mass spectrometry and quantified by gas chromatography using an internal standard for each caste and all colonies. These analyses show that although the cuticular hydrocarbons ofR. santonensis in Europe andR. flavipes in Georgia are identical, their relative proportions are different. However, the defensive compounds synthesized by their soldiers are different. A strong chemical polymorphism between sympatric colonies ofR. flavipes in the SW United States was detected in terms of both the hydrocarbons of the workers and soldiers and in the defensive secretions of the soldiers. The six defensive secretion phenotypes are based on the presence or absence of terpenes whereas the cuticular hydrocarbon phenotypes are based on significant differences in the proportions of the various components. A multivariate analysis (analysis of principal components) clearly permitted discrimination of four phenotypes (three inR. flavipes and one inR. santonensis) without intermediates. The hydrocarbons responsible for these variations were identified, and it was shown that the variations are neither seasonal nor geographic. The phenotypes of the cuticular hydrocarbons (workers and soldiers) and defensive compounds are linked in each colony, forming in three groups inR. flavipes Georgia, one subdivided into four subgroups according to the defensive secretion phenotypes. The role of these polymorphisms is discussed and ethological tests indicate that the chemical polymorphism do not determine aggressive behavior. The taxonomic significance of these results is considered and two hypothesis are formulated: (1) We only detected a strong genetic polymorphism in one unique species, and we believe thatR. santonensis was introduced into Europe in the last century from oneR. flavipes colony. (2) Chemical variability characterizes the sibling species that can be grouped into the same subspeciesR. flavipes. Unknown mechanisms of reproductive isolation separate them.     

Induced mimicry of colony odors in ants

The cuticular hydrocarbons ofFormica selysi (Formicinae) andMonica rubida (Myrmicinae) reared in single species and in mixed species colonies were determined using gas chromatography (GC) and GC-mass spectrometry. In colonies containing both species, each species modified its species-specific recognition odor. This odor is composed, at least partly, of cuticular hydrocarbons. The cuticular hydrocarbons ofM. rubida consist only of saturated alkanes (n-alkanes and branched alkanes). InF. selysi the mixture also contains unsaturated compounds (monoenes and dienes). In hetero-specific colonies, a new chemical signature developed. This signature resulted from qualitative and quantitative changes in the spectrum of hydrocarbons produced by each species and permitted the two species to inhabit the same nest without displaying interspecific aggression. The readjustment seemed to be more an active synthesis or an active transfer than simply a passive transfer from one species to the other. This may imply that the ants synthesized some components of the hydrocarbon signature of the other species. These synthesizing processes may be activated under particular social environmental conditions.     

Variations in Worker Cuticular Hydrocarbons and Soldier Isoprenoid Defensive Secretions Within and Among Introduced and Native Populations of the Subterranean Termite, Reticulitermes flavipes

In social insects, cuticular hydrocarbons (CHCs) play a central role in nestmate recognition. CHCs have proved to be useful for identifying species and differentiating populations. In combination with CHCs, isoprenoid soldier defensive secretions (SDSs) have been previously used in some termite species for chemotaxonomic analyses. This study compared the levels of chemical variation within and among introduced (French) and native (U.S.) populations of the subterranean termite, Reticulitermes flavipes. Worker CHCs and soldier SDSs from termites collected from colonies in nine populations in Florida, Louisiana, and France were analyzed. Discriminant analyses revealed that both localities and populations can be distinguished by using the variation in CHC profiles. Principal component analyses of CHC profiles as well as the calculation of two distance parameters (Nei and Euclidean) revealed remarkable chemical homogeneity within and among French populations. These analyses also showed that the CHC profiles of French populations were closer to termite populations from Louisiana than to those from Florida. Of the six distinct SDS chemotypes, one was common to populations in France and Louisiana. The possibility that populations in France originated from Louisiana, and the potential causes and consequences of chemical homogeneity within introduced populations are discussed.     

Role of cuticular hydrocarbons of aphid parasitoids in their relationship to aphid-attending ants

Lysiphlebus cardui, the dominant aphidiid parasitoid of the black bean aphid,Aphis fabae cirsiiacanthoidis (Afc), on creeping thistle, is able to forage in ant-attended aphid colonies without being attacked by ants. Several behavioral observations and experimental studies led to the hypothesis thatL. cardui mimics the cuticular hydrocarbon profile of its host aphid. Chemical analysis of the cuticular extracts revealed that bothL. cardui and Afc exclusively possess saturated hydrocarbons:n-alkanes, monomethyl (MMA), dimethyl (DMA), and trimethyl alkanes (TMA). Comparison of the hydrocarbon profiles of parasitoid and aphid showed great qualitative resemblance between parasitoid and host:L. cardui possesses almost all host-specific compounds in addition to species-specific hydrocarbons of mainly higher molecular weight (>C₃₀). However, there is a lesser quantitative correspondence between parasitoid and host aphid. Furthermore, we analyzed the cuticular hydrocarbon profile of another parasitoid of Afc,Trioxys angelicae. This aphidiid species is vigorously attacked and finally killed by honeydewcollecting ants when encountered in aphid colonies. Its cuticular hydrocarbon profile is characterized by the presence of large amounts of (Z)-11-alkenes of chain lenghts C₂₇, C₂₉, C₃₁, and C₃₃, in addition to alkanes and presumably trienes. The role of the unsaturated hydrocarbons onT. angelicae as recognition cues for aphid-attending ants is discussed.     

Temporal changes in colony cuticular hydrocarbon patterns ofSolenopsis invicta

Heritable cuticular hydrocarbon patterns ofSolenopsis invicta workers are consistent within colonies for a given sampling time but vary sufficiently from colony to colony to distinguish the colonies from each other. In addition, cuticular hydrocarbon patterns change within colonies over time. Nestmate recognition cues found on the individual's cuticle, can be from heritable or environmental sources, and are a subset of colony odor. The cuticular hydrocarbons can be used as a model for heritable nestmate recognition cues. We propose that because potential nestmate recognition cues, both environmental and genetic, are dynamic in nature rather than static, during its lifetime a worker must continually update its perception (template) of colony odor and nestmate recognition cues.     

Harvester Ants Utilize Cuticular Hydrocarbons in Nestmate Recognition

Cuticular hydrocarbons appear to play a role in ant nestmate recognition, but few studies have tested this hypothesis experimentally with purified hydrocarbon extracts. We exposed captive colonies of the harvester ant Pogonomyrmex barbatus to small glass blocks coated with whole cuticular lipid extracts and the purified hydrocarbon portion of extracts from nestmate and nonnestmate workers. As an estimate of agonistic behavior, we measured the proportion of ants in contact with blocks that flared their mandibles. Blocks coated with cuticular extracts from nonnestmates were contacted by more workers in one of two experiments and elicited higher levels of aggression in both experiments than blocks bearing extracts from nestmates. The cuticular hydrocarbon fraction of extracts alone was sufficient to elicit agonistic behavior toward nonnestmates. The results demonstrate that harvester ants can perceive differences in cuticular hydrocarbon composition, and can use those differences in nestmate recognition.     

Cuticular hydrocarbons ofAedes hendersoni cockerell andA. triseriatus (SAY)

Field-caught adult male and femaleAedes hendersoni are difficult to distinguish from the sibling speciesA. triseriatus. We found that mosquitoes from the same sex of the sibling species can not be readily separated either by unique cuticular hydrocarbon components or by differences in percent composition of those components. Multivariate analysis of the cuticular hydrocarbon data does not provide good separation. Cuticular hydrocarbons were identified using gas chromatography electron-impact mass spectrometry and gas chromatography chemical-ionization mass spectrometry. Flame-ionization capillary gas chromatography was used for quantitative analysis of individual mosquitoes. Sixty-four hydrocarbons with chain lengths from C₁₆ to greater than C₄₆ were common to both species. Identified hydrocarbon components weren-alkanes, monomethylalkanes, dimethylalkanes, trimethylalkanes, and alkenes.Diptera: Culicidae.     

Hydrocarbons ofNasutitermes acajutlae and comparison of methodologies for sampling cuticular hydrocarbons of caribbean termites for taxonomic and ecological studies

Using data from the arboreal nestingNasutitermes acajutlae (Holmgren), we propose standard collection and extraction methodology for characterization of cuticular hydrocarbons of termites under field conditions in the tropics. Specifically, we evaluated: (1) the effect of the duration and the number of extractions; (2) the effect of drying termites before extraction; (3) the effect of sample size; (4) the effect of solvents (ethanol versus hexane) on cuticular hydrocarbon profiles. Olefins comprise ca. 70% of the cuticular hydrocarbons ofN. acajutlae. Hydrocarbons consist of two distinct groups: early-eluting components, primarilyn-alkanes and methyl-branched alkanes, and late-eluting compounds, which consist almost exclusively of unsaturated components with one to six double bonds. Soldiers have more early-eluting compounds than workers or alates. Nests from the same island had qualitatively similar, but quantitatively dissimilar hydrocarbon mixtures. Brief extractions of 300 live workers in 10 ml of hexane for only 20 sec produced a hydrocarbon mixture equivalent to a 10-min extraction. Long-term extraction of 300 workers in hexane for two years resulted in different mixtures of hydrocarbons. Drying workers tended to enhance extraction of the less abundant unsaturated compounds such as C_41.4 and C_41.5. A single extraction of a minimum of 100 workers (live or dried), with hexane for 20 sec to 10 min is best; these extraction regimes resulted in mixtures of hydrocarbons that are quantitatively very similar. For quantitative comparisons, extracts from dried samples should not be compared to those from live samples. Storage in ethanol caused numerous unidentified, nonhydrocarbon compounds to be extracted either from the cuticle or from internal tissues.     

Cuticular Hydrocarbons of Buffalo Fly, <Emphasis Type="Italic">Haematobia exigua</Emphasis>, and Chemotaxonomic Differentiation from Horn Fly, <Emphasis Type="Italic">H. irritans</Emphasis>

We determined the quantity and chemical composition of cuticular hydrocarbons of different strains, sexes, and ages of buffalo flies, Haematobia exigua. The quantity of cuticular hydrocarbons increased from less than 1 μg/fly for newly emerged flies to over 11 μg/fly in 13-d-old flies. The hydrocarbon chain length varied from C₂₁ to C₂₉, with unbranched alkanes and monounsaturated alkenes the major components. Newly emerged flies contained almost exclusively C₂₇ hydrocarbons. Increasing age was accompanied by the appearance of hydrocarbons with shorter carbon chains and an increase in the proportion of alkenes. 11-Tricosene and 7-tricosene were the most abundant hydrocarbons in mature H. exigua. Cuticular hydrocarbons of H. exigua are distinctly different from those of horn flies, Haematobia irritans. The most noticeable differences were in the C₂₃ alkenes, with the major isomers 11- and 7-tricosene in H. exigua and (Z)-9- and (Z)-5-tricosene in H. irritans, respectively. Cuticular hydrocarbon analysis provides a reliable method to differentiate the two species, which are morphologically difficult to separate. The differences in cuticular hydrocarbons also support their recognition as separate species, H. exigua and H. irritans, rather than as subspecies.     

Segregation of colony odor in the desert ant Cataglyphis niger

There are two separate, and presumably opposing, processes that affect colony odor in the desert ant Cataglyphis niger: (1) biosynthesis and turnover of these chemicals by individual ants, and (2) homogenization of colony odor through exchange of cues. The first increases signal variability; the latter decreases it. The impact of these factors was tested by splitting colonies and monitoring the profile changes occurring in the postpharyngeal glands (PPG) and cuticular hydrocarbons.From each of two polygynous nests four daughter colonies were formed, three monogynous and one queenless. Thereafter, 10 ants from each were randomly selected each month, for three successive months, for analyses of their PPG and cuticular hydrocarbons. From two colonies we also obtained ants from a known matriline. Over time, there was a shift in hydrocarbon profiles of both the PPG and cuticular washes in each of the tested colonies. Moreover, by subjecting selected hydrocarbon constituents to a discriminant analyses based on their relative proportions, all of the daughter colonies (queenright and queenless) were distinguishable from each other and from their respective mother colonies. In each of the queenright daughter colonies, the queen profile was indiscriminable from that of the workers and often was in the center of the group. Full sisters were clearly distinguishable from their nestmates, emphasizing the genetic versus environmental processes that govern colony odor. The effect of time was always superior to the separation effect in contributing to odor segregation. Comparison of the Mahalanobis distances indicated that the shift in hydrocarbon seems to proceed along parallel lines rather than in divergence. However, there was no overt aggression between ants that originated from the different subgroups in dyadic encounters. It appears that in this species a three-month separation period is not sufficient to change the hydrocarbon profile beyond the recognition threshold.     

Identification and Characterization of Cuticular Hydrocarbons from a Rapid Species Radiation of Hawaiian Swordtailed Crickets (Gryllidae: Trigonidiinae: <Emphasis Type="Italic">Laupala</Emphasis>)

A previous investigation of cuticular hydrocarbon variation among Hawaiian swordtail crickets (genus Laupala) revealed that these species differ dramatically in composition of cuticular lipids. Cuticular lipid extracts of Laupala species sampled from the Big Island of Hawaii also possess a greatly reduced number of chemicals (as evidenced by number of gas chromatography peaks) relative to ancestral taxa sampled from the geologically older island of Maui. One possible explanation for this biogeographic pattern is that reduction in chemical diversity observed among the Big Island taxa represents the loss of ancestral hydrocarbons found on Maui. To test this hypothesis, we characterized and identified the structures of cuticular hydrocarbons for seven species of Hawaiian Laupala, two from Maui (ancestral) and five from the Big Island of Hawaii (derived) by using gas chromatography-mass spectrometry. Big Island Laupala possessed a reduced number of alkenes as well as a reduction in the diversity of methyl-branch positions relative to species sampled from Maui (ancestral), thus supporting our hypothesis of a founder-induced loss of chemical diversity. The reduction in diversity of ancestral hydrocarbons was more severe within one of the two sister lineages on the Big Island, suggesting that post-colonizing processes, such as drift or selection, also have influenced hydrocarbon evolution in this group.     

Roles of cuticular hydrocarbons in intra-and interspecific recognition behavior of two rhinotermitidae species

Soldiers of two termite species.Reticulitermes speratus andCoptotermes formosanus, showed aggressive behavior toward workers of other species. Soldiers always exhibited aggressive behavior to a conspecific worker treated with heterospecific cuticular hydrocarbons. A bioassay using live workers to test contact chemical cues was developed.