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.     

Cuticular Hydrocarbons of Termites of the British Virgin Islands

A survey of the termites (Isoptera) of 17 islands of the British Virgin Island (BVI) complex yielded eight taxa belonging to three families. The Kalotermitidae include Neotermes mona (Banks), Cryptotermes brevis (Walker), Procryptotermes corniceps (Snyder), and an undetermined species of Incisitermes, likely Incisitermes nr snyderi (Light) or I. incisus (Silvestri). The only rhinotermitid collected is an undetermined species of Heterotermes (Froggatt). Parvitermes wolcotti (Snyder), Nasutitermes costalis (Holmgren), and N. acajutlae (Holmgren) comprise the Termitidae. Cuticular hydrocarbon mixtures were characterized for each of the taxa. Blends of abundant hydrocarbons are species-specific and can be used to identify a given taxon without the diagnostic castes, soldiers, or imagoes, although the species of Incisitermes were not separable on the basis of cuticular hydrocarbons.     

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 of four populations ofCoptotermes formosanus Shiraki in the united states

The degree of similarity among cuticular hydrocarbon profiles of four populations ofCoptotermes formosanus Shiraki in the United States is reported. Sixteen individual or isomeric mixtures of hydrocarbons were identified by gas chromatography-mass spectrometry. Hydrocarbon components consist ofn-alkanes, 2-methylalkanes, 3-methylalkanes, internally branched monomethylalkanes on carbons 9–15, and dimethylalkanes. The predominant hydrocarbons have 27 carbons in the parent chain. Methyl-branched hydrocarbons are more abundant thann-alkanes. No qualitative differences were apparent in the hydrocarbon components of workers or soldiers from any of the four populations. Quantitative differences in the hydrocarbon components separate castes and populations into different concentration profiles. Stepwise discriminant analysis and canonical discriminant analysis were used to choose and display seven hydrocarbon components for workers and three for soldiers that best reveal the differences among populations. Within-population variation is low compared to the differences among populations. These results suggest thatC. formosanus from Hallandale, Florida; New Orleans, Louisiana; and Lake Charles, Louisiana, are not related to those from Honolulu, Hawaii, and probably originated from other geographical locations.Isoptera: Rhinotermitidae.     

Antitermitic activity ofLonchocarpus castilloi flavonoids and heartwood extracts

The heartwood of the tropical treeLonchocarpus castilloi Standley (Leguminosae) is highly resistant to attack by the drywood termitesCryptotermes brevis (Walker); nevertheless successive extraction with hexane, diethyl ether, acetone, methanol, and water reduced its resistance to these organisms. Antitermitic properties of the extracts were bioassayed using impregnated filter paper disks. Although the five extracts reduced both feeding and survival ofC. brevis, no significant differences among them were detected. Choice feeding tests showed that termites avoided eating the paper treated with the extracts. Two flavonoid compounds isolated from the heartwood, castillen D and castillen E, impregnated into filter paper showed concentration-dependent feeding deterrent activity, but were not toxic toC. brevis.     

(Z,E,E)-dodecatrien-1-ol: A minor component of trail pheromone of termite,Coptotermes formosanus Shiraki

In the course of the elucidation of the primary structure of an isolated trail pheromone fromC. formosanus, a minor component that had the same molecular weight as the major trail pheromone, (Z,Z,E)-3,6,8-dodecatrien-1-ol [(Z,Z,E)-DTE-OH], was detected in the mass chromatogram ofm/z 180 of capillary GC-MS. The mass spectrum of the minor component showed a prominent pattern of dodecatrien-1-ol. Chemical analysis demonstrated that the complete structure was (Z,E,E)-DTE-OH. Furthermore, capillary GC-MS-HR-SIM analysis indicated that the component existed only in the workers ofCoptotermes formosanus Shiraki and was not present in workers ofReticulitermes speratus (Kolbe). This minor component may be a species-specific factor ofC. formosanus, although this was not suggested by a two-choice bioassay.     

Trail-following pheromones of the rhinotermitidae: Approaches to their authentication and specificity

A method for determining the authenticity of subterranean termite trail pheromones is suggested and utilized to verify the presence of trail pheromones inReticulitermes virginicus, R. flavipes, andR. tibialis. In addition, a possible trail pheromone has been demonstrated forCoptotermes formosanus. A choice bioassay method shows that the above trail pheromones are species specific.     

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.     

Identification of trail pheromone precursors from Subterranean termite,Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae)

Whole-body extracts of the termite,Coptotermes formosanus Shiraki served for examining the presence of trail pheromone precursor(s). Three trail pheromone precursor candidates, identified as dodecatrienyl stearate, dodecatrienyl oleate, and dodecatrienyl linoleate, were isolated using various chromatographic methods in conjunction with bioassay and by capillary GC-MS analyses.     

Hydroquinone Is Not A Phagostimulant For The Formosan Subterranean Termite

It has been suggested that hydroquinone found in the labial glands of a number of termite species acts as a primary phagostimulating factor. We tested hydroquinone as a phagostimulant using workers from three colonies of the Formosan subterranean termite, Coptotermes formosanus, under both laboratory and field conditions. Hydroquinone at concentrations ranging from ca. 0.002–20.0 ng/cm² did not increase visitation by C. formosanus workers to treated over control filter papers, and was actually repellent at a 20 ng/cm² dose. No phagostimulant response to hydroquinone was observed in two colonies. In the third, there was a significant increase in feeding on filter paper treated with a 2 ng/cm² dose, but was significantly lower at a 20 ng/cm² dose. Furthermore, sand treated with a gradient of hydroquinone, did not evoke increased tunneling activity compared with controls. GC-MS analysis of C. formosanus workers indicated that hydroquinone was present at an average of 41 pg/worker. It was also determined that within one week about 11%hydroquinone in aqueous solution oxidized to 1,4-benzoquinone. Our findings indicate that hydroquinone alone does not act as a phagostimulant but instead may act as a repellent at higher concentrations. The attractant/arrestant of the Formosan termite may have multiple components of which hydroquinone, at low doses, could be one.     

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.     

Quantitative Changes in Hydrocarbons over Time in Fecal Pellets of Incisitermes minor May Predict Whether Colonies Are Alive or Dead

Hydrocarbon mixtures extracted from fecal pellets of drywood termites are species-specific and can be characterized to identify the termites responsible for damage, even when termites are no longer present or are unable to be recovered easily. In structures infested by drywood termites, it is common to find fecal pellets, but difficult to sample termites from the wood. When fecal pellets appear after remedial treatment of a structure, it is difficult to determine whether this indicates that termites in the structure are still alive and active or not. We examined the hydrocarbon composition of workers, alates, and soldiers of Incisitermes minor (Hagen) (family Kalotermitidae) and of fecal pellets of workers. Hydrocarbons were qualitatively similar among castes and pellets. Fecal pellets that were aged for periods of 0, 30, 90, and 365 days after collection were qualitatively similar across all time periods, however, the relative quantities of certain individual hydrocarbons changed over time, with 19 of the 73 hydrocarbon peaks relatively increasing or decreasing. When the sums of the positive and negative slopes of these 19 hydrocarbons were indexed, they produced a highly significant linear correlation (R ²?=?0.89). Consequently, the quantitative differences of these hydrocarbons peaks can be used to determine the age of worker fecal pellets, and thus help determine whether the colony that produced them is alive or dead.     

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.     

Lignoceric Acid and Hexacosanoic Acid: Major Components of Soldier Frontal Gland Secretions of the Formosan Subterranean Termite (Coptotermes formosanus)

Qualitative and quantitative analyses were performed on trimethylsilyl derivatives of soldier frontal gland secretions of the Formosan subterranean termite, Coptotermes formosanus Shiraki, by using gas chromatography–mass spectrometry. Ranges of 17.23–33.78 mg/g (acid/wet weight of secretion) of lignoceric acid and 5.39–7.67 mg/g of hexacosanoic acid were found in the soldier frontal gland secretion of three different colonies. This is the first report that organic acids occur in the soldier secretions of this species.     

Using wood extracts to determine the feeding preferences of the western drywood termite,Incisitermes minor (Hagen)

Nymphs of the western drywood termite,Incisitermes minor (Hagen), were tested for their feeding preferences on wood and extracts of 11 tree species. The amount of wood consumed was inversely proportional to its specific gravity, but methanol extracts of least preferred woods were also least preferred when termites were confined to paper treated with extracts. In choice tests, only paper treated with extract of wood from which the colony developed and untreated and methanol-treated controls were significantly fed upon. Ponderosa pine extract applied to Douglas fir and sugar pine significantly decreased the amount of wood consumed. Resistance to termite feeding appeared to depend on the presence of repellent chemicals in the wood.     

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.     

PFG‐NMR measurement of self‐diffusion coefficients of long‐chain α‐olefins and their mixtures in semi‐crystalline polyethylene

The self‐diffusion coefficients of C6–C16 long‐chain α‐olefins and their mixtures in semi‐crystalline polyethylene were measured through the pulsed field gradient nuclear magnetic resonance (PFG‐NMR). The effects of chain length, polyethylene (PE) type, and co‐monomer type in PE on the diffusion coefficients were investigated. Moreover, the influence of halohydrocarbon, cycloalkanes, and arene solvents on the diffusion coefficients of C12 α‐olefin in PE was characterized. The results have demonstrated that the diffusion coefficient of the single‐component α‐olefin in PE decreases exponentially with the increase of the carbon number of α‐olefin, and the crystallinity and crystal morphology of PE play a more important role than the co‐monomer type in determining the diffusion coefficients of α‐olefins. In addition, the apparent diffusion coefficients were used to represent the diffusion behaviors of the α‐olefin mixtures in PE. Owing to the presence of other hydrocarbon solvents, namely trichloromethane, cyclohexane, and benzene, the diffusion coefficients of C12 long‐chain α‐olefin in PE are significantly enhanced, and such promoting effect of the hydrocarbon solvents in polyolefin elastomer (POE) is much stronger than those in high‐density polyethylene (HDPE) and linear low‐density polyethylene (LLDPE). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44143.     

Surface hydrocarbon components of two species ofNasutitermes from Trinidad

Colonies ofNasutitermes costalis (Holmgren) andN. ephratae (Holmgren) were collected from five locations in Trinidad. Cuticular hydrocarbons were characterized by gas chromatography-electron impact mass spectrometry and quantified by capillary gas chromatography. Sixteen major components were identified; all but one component (12, 16-dimethyltriacontane) were common to both species. The methyl-branched hydrocarbons were predominant inN. costalis, while the majority of the hydrocarbon components inN. ephratae weren-alkanes. One hydrocarbon (11,15-dimethylheptacosane) was found in abundance in samples ofN. ephratae from Trinidad but was not previously reported from collections of this species in Panama. In addition to the morphology of the soldiers and alates and the architecture of the arboreal nests,N. costalis andN. ephratae from Trinidad can easily be separated by chromatograms of the hydrocarbons.N. costalis has an enormous 13,17-dimethylhentriacontane peak (mean = 42.4% of total hydrocarbon). InN. ephratae this peak is much smaller and the 12,16-dimethyltriacontane peak is completely missing.N. costalis from Trinidad andN. corniger from Panama appear to have cuticular hydrocarbon profiles that are more similar to one another than are those ofN. ephratae from Trinidad and Panama.Isoptera: Termitidae: Nasutitermitinae.     

Chemical Interaction among Termite-Associated Microbes

Bacteria and fungi in shared environments compete with one another for common substrates, and this competition typically involves microbially-produced small molecules. An investigation of one shared environmental niche, the carton material of the Formosan subterranean termite Coptotermes formosanus, identified the participants on one of these molecular exchanges. Molecular characterization of several termite-associated actinobacteria strains identified eleven known antimicrobial metabolites that may aid in protecting the C. formosanus colony from pathogenic fungal infections. One particular actinobacterial-derived small molecule, bafilomycin C1, elicited a strong chemical response from Trichoderma harzianum, a common soil saprophyte. Upon purification and structure elucidation, three major fungal metabolites were identified, t22-azaphilone, cryptenol, and homodimericin A. Both t22-azaphilone and homodimericin A are strongly upregulated, 123- and 38-fold, respectively, when exposed to bafilomycin C1, suggesting each play a role in defending T. harzianum from the toxic effect of bafilomycin C1.     

Effects of Plant Flavonoids on Fecundity, Survival, and Feeding of the Formosan Subterranean Termite

Fecundity, mortality, and food consumption of the Formosan subterranean termite, Coptotermes formosanus Shiraki, were evaluated in response to five plant flavonoids (genistein, biochanin A, apigenin, quercetin, and glyceollin). Apigenin fed at 50 g/primary reproductive pair proved to be the most toxic flavonoid. Biochanin A was most effective in reducing fecundity. Subsequently, these two flavonoids were tested through oral feeding and topical application at 100-g dose. Significant reduction in the numbers of progeny was evident for biochanin A in both treatment methods. Choice feeding tests with termite workers showed that initially termites were attracted to filter paper treated with biochanin A, but over a period of 72 hr, consumed significantly less material when compared to controls. Biochanin A is a promising phytochemical with ability to reduce fecundity in primary reproductives of the Formosan subterranean termite, but it does not elicit phagostimulant activity.