Hydrocarbon Profiles Research Articles

Highly diverse cuticular hydrocarbon profiles but no evidence for aggression towards non-kin in the ambrosia beetle Xyleborinus saxesenii.

Animal societies use nestmate recognition to protect against social cheaters and parasites. In most social insect societies, individuals recognize and exclude any non-nestmates and the roles of cuticular hydrocarbons as recognition cues are well documented. Some ambrosia beetles live in cooperatively breeding societies with farmed fungus cultures that are challenging to establish, but of very high value once established. Hence, social cheaters that sneak into a nest without paying the costs of nest foundation may be selected. Therefore, nestmate recognition is also expected to exist in ambrosia beetles, but so far nobody has investigated this behavior and its underlying mechanisms. Here we studied the ability for nestmate recognition in the cooperatively breeding ambrosia beetle Xyleborinus saxesenii, combining behavioural observations and cuticular hydrocarbon analyses. Laboratory nests of X. saxesenii were exposed to foreign adult females from the same population, another population and another species. Survival as well as the behaviours of the foreign female were observed. The behaviours of the receiving individuals were also observed. We expected that increasing genetic distance would cause increasing distance in chemical profiles and increasing levels of behavioural exclusion and possibly mortality. Chemical profiles differed between populations and appeared as variable as in other highly social insects. However, we found only very little evidence for the behavioural exclusion of foreign individuals. Interpopulation donors left nests at a higher rate than control donors, but neither their behaviours nor the behaviours of receiver individuals within the nest showed any response to the foreign individual in either of the treatments. These results suggest that cuticular hydrocarbon profiles might be used for communication and nestmate recognition, but that behavioural exclusion of non-nestmates is either absent in X. saxesenii or that agonistic encounters are so rare or subtle that they could not be detected by our method. Additional studies are needed to investigate this further.

Aphid-Ant Relationships: The Role of Cuticular Hydrocarbons and Different Chemical Stimuli in Triggering Mutualistic Behavior

In ant-aphid interactions, various aphid species offer honeydew to the ant partner and increase their density by ant attendance, whilst others never attend ant species, in which case ants tend to treat them as prey. In this regard, ants should have the ability to distinguish myrmecophile aphid species from non-mutualistic species, so that mutualistic aphids will be accepted as partners rather than prey. Although ant-aphid interactions are now the focus of chemical ecology studies, the role of the different chemical stimuli in determining mutualistic interactions has not been completely clarified. Therefore, we have investigated the cuticular hydrocarbon profile of four myrmecophiles aphid species using GC-MS. We also investigated the behavior of the worker-ants (Lasius niger L., Hymenoptera: Formicidae) to different chemical stimuli derived from aphids. We applied four treatments and found that the behavior of the ant workers varied depending on the source of the different treatments. In particular, the real aphid Aphis pomi and the sugar solution proved to be the most attractive to the ants, while the presence of pure extract of the individuals is enough to disturb the behavior of the ants. We provide evidence that the key stimuli of the tending behavior could be the CHC patterns of the aphids and the CHC profile of the aphids tends to be genus specific. This research will promote further investigations to test the behavior of ant workers towards other species of aphids and treatment combinations.

Study on metabolic response of female and male Trogoderma varia-bile (Ballion) on different host grain using direct immersion solid-phase microextraction coupled with gas chromatography mass

The purpose of this study is to use the technique of gas chromatography coupled with mass spectrometry to study the metabolite profile of Trogoderma variabile using different host grains including canola, oats, wheat, and barley. Also, hydrocarbon profiling can be used as a chemo-taxonomical tool for insect species identification, especially for very morphologically similar species like T. granarium. For sample preparation insects were subjected to extraction with acetonitrile. Direct Immersion-Solid Phase Microextraction (DI-SPME) was employed, followed by Gas Chromatography-Mass Spectrometry analysis (GC-MS) for the collection, separation, and identification of compounds. Additionally, insect host grains have a significant effect on the insect chemicals that are identified from T. variabile adults such as fatty acid and hydrocarbons. Results showed that insect host grains have a significant influence on the chemical compounds that are identified in females and males. There were twenty-three compounds were identified from adults reared on canola and wheat. However, there were 26 and 28 compounds detected from adults reared on oats and barley respectively. Results also showed that 11-methylpentacosane; 13-methylheptacosane; heptacosane; docosane, 1-iodo- and nonacosane were the most significant compounds that identified form T. variabile male reared on different host grains. However, the main compounds identified from female cultured on different host grains include docosane, 1-iodo-; 1-butylamine, N-butyl-; oleic acid; heptacosane; 13-methylheptacosane; hexacosane; nonacosane; 2-methyloctacosane; n-hexadecanoic acid and docosane in the female samples.

Cuticular Hydrocarbon Profiles of Himalayan Bumble Bees (Hymenoptera: Bombus Latreille) are Species-Specific and Show Elevational Variation.

Bumble bees are important pollinators in natural environments and agricultural farmlands, and they are in particular adapted to harsh environments like high mountain habitats. In these environments, animals are exposed to low temperature and face the risk of desiccation. The Eastern Himalayas are one of the recognized biodiversity hotspots worldwide. The area covers subtropical rainforest with warm temperature and high precipitation as well as high mountain ranges with peaks reaching up to 7,000m, shaping a diverse floral and faunal community at the different elevational zones. To identify possible adaptation strategies, we investigated the cuticular hydrocarbon profiles of four bumble bee species occurring at different elevational ranges in Arunachal Pradesh, the northeastern most state in India. At 17 locations along an elevational gradient, we collected workers of two species from lower elevations (B. albopleuralis and B. breviceps; ~ 100m - 3,000m asl) and two species from higher elevations (B. prshewalskyi and B. mirus; ~ 2,800m - 4,500m asl). The CHC profiles of all four species showed a significant degree of variation in the composition of hydrocarbons, indicating species specificity. We also found clear correlation with elevation. The weighted mean chain length of the hydrocarbons significantly differed between the low and high elevation species, and the proportion of saturated hydrocarbons in CHC profiles significantly increased with the elevational range of the bumble bee species. Our results indicate that bumble bees living at high elevations reduce the risk of water loss by adapting their CHC composition on their cuticle, a phenomenon that has also been found in other insects like ants and fruit flies.

Assessment of the polycyclic aromatic hydrocarbon profile in African catfish (Clarias gariepinus) smoke-dried with selected wood energy sources

Assessment of the polycyclic aromatic hydrocarbon profile in African catfish (Clarias gariepinus) smoke-dried with selected wood energy sources

Characterization of Dominant Cuticular Hydrocarbons in Inversion and Inversion-Free Strains of <i>Drosophila ananassae</i> (Doleschall)

Cuticular hydrocarbons (CHCs) of Drosophila ananassae (Doleschall) was characterized and identified using gas chromatography and mass spectrometry (GC-MS) analysis. A high % of methyl-branched alkanes were identified in all inversion (2LA, 3LA and 2LA+3LA) and inversion-free strains followed by linear alkanes and alkenes. The present work unfolds the significant patterns of variations in the isomeric forms of methylated alkanes between the inversion and inversion free strains (F-46.6; df-3, p 0.005), and non-significant between the sex (F-2.14; df-1, p 0.2394). But in linear alkanes shows significant variation between the inversion strains (F-30.49; df-3, p 0.009) and between the male and female (F-115.45; df-1, p 0.001) was observed. In particular there is a significant correlation between the chromosomal inversion and synthesis of CHCs in D. ananassae. Unique blend of CHCs in Drosophila performs dual role as desiccation resistance and act as chemical signalling molecule. Linear alkanes are majorly involved in desiccation resistance but in methyl- branched CHCs length variation is a key determinant of desiccation resistance. Presence of longer methyl- branched alkanes and higher desiccation resistance, shorter the carbon chain length act as a signalling molecules. The current study revealed the influence of chromosomal inversion on the cuticular hydrocarbon profile in D. ananassae.

Targeted treatment of injured nestmates with antimicrobial compounds in an ant society

Infected wounds pose a major mortality risk in animals. Injuries are common in the ant Megaponera analis, which raids pugnacious prey. Here we show that M. analis can determine when wounds are infected and treat them accordingly. By applying a variety of antimicrobial compounds and proteins secreted from the metapleural gland to infected wounds, workers reduce the mortality of infected individuals by 90%. Chemical analyses showed that wound infection is associated with specific changes in the cuticular hydrocarbon profile, thereby likely allowing nestmates to diagnose the infection state of injured individuals and apply the appropriate antimicrobial treatment. This study demonstrates that M. analis ant societies use antimicrobial compounds produced in the metapleural glands to treat infected wounds and reduce nestmate mortality.

An experimental test of the evolutionary consequences of sympatry in Drosophila subquinaria.

Prezygotic isolation is often stronger between sympatric as opposed to allopatric taxa, but the underlying cause can be difficult to infer from comparative studies alone. Experimental evolution, where evolutionary responses to treatments manipulating the presence/absence of heterospecific individuals are tracked, can provide a powerful complementary approach. We used experimental evolution to investigate a naturally occurring pattern of reproductive character displacement in the mushroom-feeding fly, Drosophila subquinaria. In nature, female D. subquinaria from populations sympatric with the closely related Drosophila recens discriminate more strongly against heterospecific males than do females from allopatric populations. Starting with 16 replicate allopatric populations of D. subquinaria, we manipulated the presence/absence of D. recens during mating (experimental sympatry vs. control) and, when present, we allowed hybrids to live or kill them each generation. Across 12 generations, heterospecific offspring production from no-choice mating trials between D. subquinaria females and D. recens males declined in both experimental sympatry treatments relative to the control, suggesting increased sexual isolation. Male cuticular hydrocarbon profiles also evolved, but only in the hybrids killed treatment. Our results strongly imply that the existing reproductive character displacement in wild D. subquinaria populations was an evolutionary response to selection arising from secondary contact with D. recens.

Hybrid low salinity water and surfactant process for enhancing heavy oil recovery

Combining low salinity water (LSW) with surfactants has an enormous potential for enhancing oil recovery processes. However, there is no consensus about the mechanisms involved, in addition to the fact that several studies have been conducted in model systems, while experiments with rocks and reservoir fluids are scarce. This study presents a core-flooding experiment of LSW injection, with and without surfactant, using the core and heavy oil samples obtained from a sandstone reservoir in southeastern Mexico. The effluents and the crude oil obtained at each stage were analyzed. The study was complemented by tomographic analysis. The results revealed that LSW injection and hybrid process with surfactants obtained an increase of 11.4 percentage points in recovery factor. Various phenomena were caused by LSW flooding, such as changes in wettability and pH, ion exchange, mineral dissolution, detachment of fines and modification of the hydrocarbon profile. In the surfactant flooding, the reduction of interfacial tension and alteration of wettability were the main mechanisms involved. The findings of this work also showed that the conditions believed to be necessary for enhanced oil recovery with LSW, such as the presence of kaolinite or high acid number oil, are not relevant.

Warming up through buildings and roads: what we know and should know about the urban heat island effect on bees

Urbanization leads to cities having higher temperatures than surrounding non-urban areas [this is known as the urban heat island (UHI) effect]. Very little is known about the impacts of the UHI effect on bees, despite the importance of temperature on many aspects of bees’ life suggesting that these may be not negligible. In this study, we aimed to highlight how the UHI effect could impact relevant functional traits of bees in cities, proposing several ad hoc hypotheses for traits that have thus far been investigated only in few studies or not at all, based on what we know from non-urban studies. The UHI effect was shown to influence bee body size, and generally tended to reduce the body size of bees in cities. Urban temperature may also affect bees’ wing morphology, and thus their overall flight morphology parameters. Individuals may be more brightly colored in cities. Bee ommatidial size and the number of antennal thermoreceptors they have may be smaller and fewer, respectively, in cities than in non-urban areas. As expected, because urban bees face a higher risk of desiccation, higher proportions of alkanes and longer main-carbon chain lengths are expected in their cuticular hydrocarbon (CHC) profiles. Stress biomarkers can also occur at greater concentrations in bees in cities and specific bacteria in the bee gut may occur at lower abundances. Warm urban temperatures may impact the life cycle of pathogens by reducing their proliferation. Aggression levels may be increased, and eusocial species may present more worker phases per year due to the UHI effect. All of these proposed impacts could be likely more visible in solitary and primitively eusocial bee species, which are those suspected to have a more limited dispersal ability. Comparative studies would help in the proper testing of these hypotheses.

Cuticular hydrocarbon profiles of Aedes aegypti reproductive stages - a potential tool for identifying high epidemiological risk populations

Cuticular hydrocarbon profiles of Aedes aegypti reproductive stages - a potential tool for identifying high epidemiological risk populations

Rapid encapsulation of true ferns and arborane/fernane compounds fossilised in siderite concretions supports analytical distinction of plant fossils

Fossilised true ferns (Pecopteris sp.) preserved in siderite concretions from the Mazon Creek Lagerstätte (Illinois) presented a unique opportunity to characterise the organic signatures of these late Carboniferous plants. Localised analyses of true fern fossils showed several highly abundant phytohopanoids and fernane/arborane derived aromatic products, which were present only negligibly within their siderite matrix, as well as from other types of fossilised plants. These terpenoids had been recognised in some extant ferns, but scarcely in sedimentary organic matter and their exact source remained ambiguous. The present fossil biomarker data confirms an ancient true fern origin. Furthermore, the excellent concretion preservation of a series of related terpenoid products provided a rare insight into their diagenetic formation. The benign properties of carbonate concretions could be exploited further for biomarker evidence of other fossilised organisms, with one important caveat being that biomarker signals attributed to isolated fossils be significantly distinct from background organic matter pervading the concretion matrix. For instance, hydrocarbon profiles of seed ferns (pteridosperms) and articulates (horsetails) also preserved in Mazon Creek concretions were indistinguishable from separate analysis of their concretion matrix, preventing biomarker recognition.

Ambient Air Emission Profiles of Polycyclic Aromatic Hydrocarbons around a Typical University Power House in Nigeria

Ambient Air Emission Profiles of Polycyclic Aromatic Hydrocarbons around a Typical University Power House in Nigeria

Protection of a defensive symbiont does not constrain the composition of the multifunctional hydrocarbon profile in digger wasps.

Hydrocarbons (HCs) fulfil indispensable functions in insects, protecting against desiccation and serving chemical communication. However, the link between composition and function, and the selection pressures shaping HC profiles remain poorly understood. Beewolf digger wasps (Hymenoptera: Crabronidae) use an antennal gland secretion rich in linear unsaturated HCs to form a hydrophobic barrier around their defensive bacterial symbiont, protecting it from brood cell fumigation by toxic egg-produced nitric oxide (NO). Virtually identical HC compositions mediate desiccation protection and prey preservation from moulding in underground beewolf brood cells. It is unknown whether this composition presents an optimized adaptation to all functions, or a compromise due to conflicting selection pressures. Here, we reconstitute the NO barrier with single and binary combinations of synthetic linear saturated and unsaturated HCs, corresponding to HCs found in beewolves. The results show that pure alkanes as well as 3 : 1 mixtures of alkanes and alkenes resembling the composition of beewolf HCs form efficient protective barriers against NO, indicating that protection can be achieved by different mixtures of HCs. Since in vitro assays with symbiont cultures from different beewolf hosts indicate widespread NO sensitivity, HC-mediated protection from NO is likely important across Philanthini wasps. We conclude that HC-mediated protection of the symbiont from NO does not exert a conflicting selection pressure on the multifunctional HC profile of beewolves.

Effects of genotype and host environment on the cuticular hydrocarbon profiles of Lysiphlebus parasitoids and aggression by aphid-tending ants.

Parasitoids in the genus Lysiphlebus specialize on ant-tended aphids and have previously been reported to mimic the cuticular hydrocarbon (CHC) profiles of their aphid hosts to avoid detection by ants. However, the precise mechanisms that mediate reduced ant aggression toward Lysiphlebus spp. are not known, nor is it clear whether such mechanisms are broadly effective or specialized on particular aphid hosts. Here we explore the effects of wasp genotype and host environment on Lysiphlebus CHC profiles and ant aggression. Rearing asexual Lysiphlebus lines in different host aphid environments revealed effects of both wasp line and aphid host on wasp CHCs. However, variation in genotype and host affected different features of the CHC profile, with wasp genotype explaining most variation in linear and long-chain methyl alkanes, while aphid host environment primarily influenced short-chain methyl alkanes. Subsequent behavioural experiments revealed no effects of host environment on ant aggression, but strong evidence for genotypic effects. The influence of genotypic variation on experienced ant aggression and relevant chemical traits is particularly relevant in light of recent evidence for genetic divergence among Lysiphlebus parasitoids collected from different aphid hosts.

Profile of carcinogenic polycyclic aromatic hydrocarbons in relation with smoking status in COPD patients

Profile of carcinogenic polycyclic aromatic hydrocarbons in relation with smoking status in COPD patients

Phylogenetic analyses of Reticulitermes (Blattodea: Rhinotermitidae) from California and other western states: multiple genes confirm undescribed species identified by cuticular hydrocarbons.

Subterranean termites in the genus Reticulitermes Holmgren 1913 are among the most economically important wood-destroying pests in the western United States. Yet, there remains uncertainty regarding the taxonomy and biology of the species in this genus. The 2 species described as having distributions in this region are the western subterranean termite, Reticulitermes hesperus Banks, and the arid land subterranean termite, Reticulitermes tibialis Banks. Taxonomic studies utilizing cuticular hydrocarbon (CHC) profiles, agonistic behavior, flight phenology, and mitochondrial DNA (mtDNA) suggested that R. hesperus is a species complex comprised of 2 or more sympatric, yet reproductively isolated species. To further delineate these taxa, we examined multiple genes from samples of Reticulitermes collected in the western United States. Alates collected after recent spring and fall mating flights, as well as previously collected workers, were subjected to CHC phenotyping and DNA sequence analyses that targeted mitochondrial cytochrome oxidase subunit II (COII), mitochondrial 16S rRNA, and nuclear Internal Transcribed Spacer 1 and 2 (ITS1 and 2). Phylogenetic analyses conducted also included published sequences of other putative western Reticulitermes species. Results suggest that at least 5 species of Reticulitermes may be present in California and that Reticulitermes in Arizona consistently group into multiple clades, including samples previously identified as R. tibialis in a sister clade. These analyses further support the species status of qualitatively different CHC phenotypes and that alates swarming in spring vs. fall are reproductively isolated species.

Chemical and population genetic analysis show no evidence of ecotype formation in a European population of the parasitoid wasp Nasonia vitripennis

Ecotypes, subpopulations or strains of a single species locally adapted to divergent ecological conditions within the same habitat are often considered to be the first steps in sympatric speciation. It has been suggested that two ecotypes are distinguishable in Nasonia vitripennis, a prominent model organism for parasitic Hymenoptera, with one ecotype parasitizing fly pupae in bird nests, and the other one parasitizing fly pupae on carrion. This differentiation into two ecotypes has been hypothesized to indicate incipient sympatric speciation in populations of this globally distributed species. In the present study, we investigated the differentiation into these two distinct ecotypes focusing on chemical profiles and the population genetic divergence in a wild N. vitripennis population from the Netherlands. Isofemale lines were obtained from bird nest boxes and from deer carrion, respectively, representing both microhabitats. To test for phenotypic differentiation, we determined the surface cuticular hydrocarbon (CHC) profiles from wasps of both host patches. Using a panel of 14 microsatellites, we concordantly determined the population genetic structure and tested for genetic differentiation between foundresses obtained from both microhabitats. Both the phenotypic as well as the genetic datasets show no evidence for any kind of separation based on the postulated two ecotypes, but rather suggest free interbreeding with no gene flow interruption between the two distinct host patches. Our findings challenge previous assumptions on clearly distinguishable ecotypes in N. vitripennis, and demonstrate how a chemical ecological assessment coupled with population genetics can be instrumental in re-evaluating the potential of ecological differentiation and incipient speciation mechanisms in parasitoid wasps.

A predatory social wasp does not avoid nestmates contaminated with a fungal biopesticide.

Fungus-based biopesticides have been used worldwide for crop pest control as a safer alternative to chemical pesticides such as neonicotinoids. Both agrochemicals can be lethal and may also trigger side effects on the behavioral traits of non-target social insects, which play a crucial role in providing essential biological pest control services in agroecosystems. Here, we evaluated whether a commercial formulation of the entomopathogenic fungus Beauveria bassiana or the neonicotinoid imidacloprid causes mortality in foragers of Mischocyttarus metathoracicus. These social wasps are natural enemies of caterpillars and other herbivorous insects and inhabit both urban and agricultural environments in Brazil. We also tested whether wasps discriminate between biopesticide-exposed and unexposed conspecifics. Through a combination of laboratory (survival assay) and field experiments (lure presentation), along with chemical analyses (cuticular hydrocarbon profiles), we showed that topic exposure to the label rate of each pesticide causes a lethal effect, with the biopesticide exhibiting a slower effect. Moreover, wasps do not discriminate biopesticide-exposed from unexposed conspecifics, likely because of the similarity of their cuticular chemical profiles 24h after exposure. Overall, the delayed lethal time at the individual level, combined with the indistinctive chemical cues of exposure and the lack of discrimination by conspecifics suggests that the fungal biopesticide may ultimately pose a threat to the colony survival of this predatory wasp.

Chemotaxonomy of Tapinoma and some Dolichoderinae Ants from Europe and North Africa

Cuticular hydrocarbons of some Dolichoderinae species from France and various places like Spain, North Africa, and Italy were studied. The Tapinoma nigerrimum group was particularly analyzed and replaced in the genus Tapinoma. All species were correctly discriminated and a new hydrocarbons profile was found in Spanish mountains in the T. nigerrimum group, which was provisionally named T. sp. Spain. We added numerous unknown spots for the distribution of these ants. We also tested aggression between some T. magnum colonies and it appeared that this species forms supercolonies like other invasive species, but does not form giant supercolonies like the Argentine ant