Cuticular hydrocarbons ofReticulitermes virginicus (Banks) and their role as potential species- and caste-recognition cues

The cuticular hydrocarbon components of four castes ofReticulitermes virginicus (Banks) have been identified and quantitated. Components identified includen-alkanes; 2-, 3-, 11-, 13-, and 15-methyl-alkanes; 11,15-dimethylalkanes, (Z)-9-alkenes; (Z,Z)-7,9-dienes; and (E/Z)-6,9-dienes ranging in carbon number from C₂₁ to C₄₀. All caste forms ofR.virginicus contained the same components, but showed caste-specific proportions. Comparison of these hydrocarbons with those of the sympatric termiteR. flavipes (Kollar) suggest that cuticular hydrocarbons might serve as species- and caste-recognition cues. A bioassay was developed to test this species-recognition hypothesis, with the experimental results supporting the hypothesis.Isoptera: Rhinotermitidae.     

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.     

Biological activity of synthetic hydrocarbon mixtures of cuticular components of the female housefly (Musca domestica L.)

Mixtures of (Z)-9-alkenes (C₂₁-C₃₃),n-alkanes (C₂₁-C₃₃), and mono- and dimethylalkanes (C₂₇, C₂₉), as components of the cuticular lipids washed from the female housefly (Musca domestica L.), were synthesized and assayed for their biological activity on male houseflies. The (Z)-9-alkenes and their hydrogenatedn-alkanes were synthesized from jojoba wax components by the appropriate chain elongation. The methylalkanes were prepared by Grignard coupling reaction of the appropriate alkyl halides, catalyzed by Li₂CuCl₄. Six- to 7-day-old virgin male houseflies exhibited the highest mating strike activity toward 6- to 7-day-old virgin females. The mating strike activity of the synthetic hydrocarbons was studied by exposing 6- to 7-day old virgin males to petrol-ether-rinsed 1 to 2-day-old dead females treated with these chemicals. (Z)-9-Tricosene was the most active hydrocarbon tested when it was applied in amounts of 10 g to a washed dead female. Amounts of 5 g of (Z)-9-tricosene did not cause sexual activity in the males. Mixture of (Z)-9-alkenes showed low activity when applied at 10-g amounts. However, when mixtures were made of 5 g of (Z)-9-tricosene with 5 fig of each of certain mixtures of (Z)-9-alkenes, the striking activity became as high as that of 10 g of (Z)-9-tricosene. This might be a synergism effect. The mixtures ofn-alkanes, as well as the mono- and dimethylalkanes, showed moderate activity. When (Z)-9-tricosene was added to these materials no increase in male activity was observed.     

(Z,Z)-5,27-Tritriacontadiene: Major sex pheromone ofDrosophila pallidosa (Diptera; Drosophilidae)

A crude cuticular extract from both sexes of 3660 fruit flies (Drosophila pallidosa) was subjected to SiO₂ and AgNO₃/SiO₂ column chromatography, accompanied by bioassay for the sex pheromone activity. After three chromatographic steps, the active fraction was obtained. The main component of the active fraction was determined to be (Z,Z)-5,27-tritriacontadiene [(Z,Z)-5,27-C_33:2, on the basis of gas-liquid chromatographic analysis, chemical derivatization and gas chromatography-mass spectrometry. Synthetic (Z,Z)-5,27-C_33:2 at 5 female equivalents (FE) elicited a clear courtship response with a high courtship index amongD. pallidosa males. Therefore it was concluded that (Z,Z)-5,27-C_33:2 was a major sex pheromone component in this species.     

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.     

Structure-activity relationship of unsaturated fatty acids as mosquito ovipositional repellents

Various straight-chain unsaturated fatty acids from C₁₄ to C₂₄ were evaluated for their ovipositional repellency against gravid females of the southern house mosquitoCulex quinquefasciatus Say, and the relationship between the structures of the fatty acids and their ovipositional repellency was determined. A double bond withZ configuration was prerequisite for an unsaturated fatty acid to be highly repellent;E isomers were less active or even inactive. No relationship was found between the repellency and the number of double bonds in the unsaturated fatty acids. In C₁₈ monounsaturated fatty acids, (Z)-9 acid was more active than (Z)-11 and (Z)-6 acids, indicating that a double bond at the 9 position rendered an acid highly repellent. Among (Z)-9-alkenoic acids of different chain lengths, the most repellent was C₁₈ acid which was also more active than (Z)-11-C₂₀, (Z)-13-C₂₂, and (Z)-15-C₂₄ acids. Oleic[(Z)-9-octadecenoic]acid, which met all these criteria, was the most ovipositionally repellent among the unsaturated fatty acids tested.Diptera: Culicidae.     

Epicuticular Hydrocarbon Variation in Drosophila mojavensis Cluster Species

Epicuticular hydrocarbon variation was investigated among the three species of the Drosophila mojavensis cluster (D. mojavensis, D. arizonae, and D. navojoa) within the large D. repleta group. Because these hydrocarbons serve as contact pheromones in adult D. mojavensis, the chemical characteristics and differences in hydrocarbon profiles in populations of these three sibling species were further investigated. Twenty-seven hydrocarbon components with chain lengths ranging from C₂₈ to C₄₀, including n-alkanes, methyl-branched alkanes, n-alkenes, methyl-branched alkenes, and alkadienes were observed. Hydrocarbon profiles among the three species reared on different cactus hosts were easily aligned with previously identified components in D. mojavensis. Male and female D. navojoa possessed a 31-methyldotricont-6-ene absent in both D. arizonae and D. mojavensis, while lacking the 8,24-tritricontadiene present in these two species. D. navojoa adults had far less 2-methyloctacosane than these sibling species, but the significance of this difference was obscured by the degree of variation among populations in amounts of this hydrocarbon. Mainland and Baja California populations of D. mojavensis were fixed for differences in the amounts 8,24-tritricontadiene, 9,25-pentatricontadiene, and 9,27-heptatricontadiene, consistent with all previous studies. Amounts of 18 of the 27 hydrocarbon components were greater in flies reared on Opuntia cactus. Canonical discriminant function analysis resolved all three species into distinct, nonoverlapping groups, suggesting that epicuticular hydrocarbon profiles are species-specific in the D. mojavensis cluster. Based on the amounts of interpopulation variation in hydrocarbon profiles in these three species, we hypothesize that epicuticular hydrocarbon differences may evolve early during the formation of new species.     

(Z)-10-Heptadecen-2-one and other 2-ketones in the aggregation pheromone blend ofDrosophila martensis,D. buzzatii,andD. serido

(Z)-10-Heptadecen-2-one was identified as the major aggregation pheromone component inDrosophila martensis, D. buzzatii, andD. serido. Aliphatic 2-ketones were not detected in newly eclosed males or in virgin females of any age. The amount of (Z)-10-heptadecen-2-one in the ejaculatory bulb and on the cuticle of males increased with age. Only trace quantities of (Z)-10-heptadecen-2-one were transferred to the female during mating. 2-Tridecanone was found in the ejaculatory bulb and on the cuticle of maleD. martensis andD. buzzatii, but notD. serido. The amount of 2-tridecanone increased with age. Unexpectedly,2-tridecanone inhibited the aggregation activity of (Z)-10-heptadecen-2-one inD. buzzatii. InD. martensis, 2-tridecanone was significantly less attractive than controls but did not decrease the attractiveness of one fly equivalent of (Z)-10-heptadecen-2-one.D. serido males did not have any 2-tridecanone and the activity of (Z)-10-heptadecen-2-one was not diminished inD. serido by the presence of 2-tridecanone.     

Behavioral Response of Males to Major Sex Pheromone Component, (Z,Z)-5,25-Hentriacontadiene, of Drosophila ananassae Females

To identify sex pheromone components in Drosophila ananassae, the cuticular hydrocarbons were analyzed and bioassayed. After silicic acid and two silver nitrate–silicic acid chromatographic steps, active fractions containing (Z,Z)-5,25- and (Z,Z)-4,26-hentriacontadiene as the most abundant components were obtained. Both hydrocarbons could elicit male courtship behavior. The former was the more predominant compound and elicited a higher courtship index value than the latter. Cuticular hydrocarbon differences between D. ananassae and its close relative, D. pallidosa, and their roles in species recognition are discussed.     

Mating stimulant pheromone and cuticular lipid constituents ofFannia femoralis (Stein) (Diptera: Muscidae)

The cuticular lipids of male and femaleFannia femoralis were similar for recently emerged insects but soon began to develop chromatographic patterns characteristic of each sex. Mature females contained more C₃₁ and C₃₃ monoolefin in the cuticular lipid than males. Also, the double bonds in the monoolefins of the female lipid were situated predominantly at the eleventh and thirteenth carbons, while most of those from the males were centrally located in the molecule or at the ninth carbon.The female C₃₁ monoolefin stimulated copulation by the males, but more mating activity occurred when the saturated hydrocarbons present in the female cuticular lipids were added. The synthetic monoolefin most active as a mating stimulant pheromone was (Z)-11-hentriacontene, but the addition of female alkanes or of syntheticn-alkanes to (Z)-11-hentriacontene increased the activity of the synthetic pheromone.A portion of a dissertation intended for submission by the first author to the Graduate School of the University of Maryland in partial fulfillment of the requirements for the Ph.D. degree.Mention of a proprietary or commercial product in this paper does not constitute an endorsement of this product by the U.S. Department of Agriculture or the University of Maryland.     

Novel brominated phospholipid fatty acids from the Caribbean spongeAgelas sp.

The very long-chain fatty acids, (5E,9Z)-6-bromo-5,9-tetracosadienoic, (5E,9Z)-6-bromo-23-methyl-5,9-tetracosadienoic, (5E,9Z)-6-bromo-5,9-pentacosadienoic and (5E,9Z)-6-bromo-24-methyl-5,9-pentacosadienoic acids, were identified in the phospholipids (mainly phosphatidylethanolamine) of the spongeAgelas sp. Structure elucidation was accomplished by means of mass spectrometry and chemical transformations, including deuteration with Wilkinson's catalyst. All of the sterols from the sponge had the Δ5,7 nucleus, with 24-methylcholesta-5,7,22-trien-3β-ol (ergosterol) and 24-ethylcholesta-5,7,22-trien-3β-ol being the most abundant.     

Sources of Variation in Cuticular Hydrocarbons in the Ant Formica exsecta

Phenotypic variation arises from interactions between genotype and environment, although how variation is produced and then maintained remains unclear. The discovery of the nest-mate recognition system in Formica exsecta ants has allowed phenotypic variation in chemical profiles to be quantified across a natural population of 83 colonies. We investigated if this variation was correlated or not with intrinsic (genetic relatedness), extrinsic (location, light, temperature), or social (queen number) factors. (Z)-9-Alkenes and n-alkanes showed different patterns of variance: island (location) explained only 0.2 % of the variation in (Z)-9-alkenes, but 21–29 % in n-alkanes, whereas colony of origin explained 96 % and 45–49 % of the variation in (Z)-9-alkenes and n-alkanes, respectively. By contrast, within-colony variance of (Z)-9-alkenes was 4 %, and 23–34 % in n-alkanes, supporting the function of the former as recognition cues. (Z)-9-Alkene and n-alkane profiles were correlated with the genetic distance between colonies. Only n-alkane profiles diverged with increasing spatial distance. Sampling year explained a small (5 %), but significant, amount of the variation in the (Z)-9-alkenes, but there was no consistent directional trend. Polygynous colonies and populous monogynous colonies were dominated by a rich C_23:1 profile. We found no associations between worker size, mound exposure, or humidity, although effect sizes for the latter two factors were considerable. The results support the conjecture that genetic factors are the most likely source of between-colony variation in cuticular hydrocarbons.     

Sponge fatty acids. 3. Occurrence of series of n−7 monoenoic andiso-5,9 dienoic long-chain fatty acids in the phospholipids of the marine spongeCinachyrella aff.schulzei keller

The fatty acid composition of phospholipids from the New Caledonian spongeCinachyrella aff.schulzei Keller was studied. More than 60 fatty acids were identified as methyl esters andN-acyl pyrrolidides by gas chromatography and gas chromatography/mass spectrometry. Two isoprenoid fatty acids also were shown to be present, namely 4,8,12-trimethyltridecanoic and 5,9,13-trimethyltetradecanoic acids. The unusual 6-tetradecenoic, 6-pentadecenoic, 12-nonadecenoic and 26-methylheptacosanoic (iso-28∶0) acids were found for the first time in sponge phospholipids. A series of six n−7 monoenoic long-chain fatty acids (C₂₃ to C₂₈) were identified, including the rare 16-tricosenoic, 18-pentacosenoic and 21-octacosenoic acids. Fifteen fatty acids possessing the typical 5,9 dienoic moiety accounted for 30% of the total fatty acid mixture. Two new fatty acids were identified, namely 5(Z)-octacosenoic and 27-methyl-5(Z),9(Z)-octacosadienoic (iso-5,9-29∶2). Based on gas chromatography/Fourier transform infrared experiments, the double bonds were assigned the (Z) configuration. For part 2 of this series, see Reference 1.     

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.     

Cuticular hydrocarbons of the eastern subterranean termite,Reticulitermes flavipes (Kollar) (Isoptera: Rhinotermitidae)

Major cuticular hydrocarbon components in several castes ofReticulitermes flavipes (Kollar) have been identified and quantitated. Types of hydrocarbons present includen-alkanes, 2-methylalkanes, 3-methylalkanes, 5-methylalkanes, an alkene, and an alkadiene, with a range in carbon numbers from C₂₁ to C₂₆, This is the first report on insect cuticular hydrocarbons in which both 2- and 3-methylalkanes are present, as well as the first report of an insect with a conjugated alkadiene.     

Premating Isolation Is Determined by Larval Rearing Substrates in CactophilicDrosophila mojavensis. III. Epicuticular Hydrocarbon Variation Is Determined by Use of Different Host Plants inDrosophila mojavensis andDrosophila arizonae

Adult epicuticular hydrocarbon profiles of male and femaleDrosophila mojavensis have been implicated as determinants of mate choice leading to premating isolation between geographically isolated populations. Hydrocarbon profiles of a Baja California and a mainland Sonora population ofDrosophila mojavensis, ayellow body mutant strain ofD. mojavensis, and a population ofD. arizonae were compared among flies that had been reared on two cactus substrates and a synthetic laboratory growth medium in order to assess the degree to which natural rearing substrates influence adult hydrocarbon composition. Twenty epicuticular hydrocarbon components, ranging from C₂₉ to C₄₁, were recovered by gas chromatography that represented major classes of alkanes, alkenes, and alkadienes. We found differences in relative amounts of epicuticular hydrocarbons among Baja and mainlandD. mojavensis, and theyellow body mutants. There were few differences betweenD. mojavensis andD. arizonae. The effects of rearing substrates were remarkable: most of the differences were due to the effects of lab food vs. cactus, but there were significant rearing substrate effects due to differences in the two cacti used. Eleven hydrocarbon components differed in abundance between males and females or showed significant sex × rearing substrate interactions from ANOVA. The effects of rearing substrates on epicuticular hydrocarbon composition inD. mojavensis are concordant with changes in the intensity of premating isolation between populations, implicating host ecology as a major determinant in patterns of mate choice in this species.     

Identification of Novel α-Methoxylated Phospholipid Fatty Acids in the Caribbean Sponge <Emphasis Type="Italic">Erylus goffrilleri</Emphasis>

The phospholipid fatty acid composition of the Caribbean sponge Erylus goffrilleri is described for the first time. A total of 70 fatty acids with chain lengths between 13 and 29 carbons were identified in the sponge. Methyl-branched fatty acids predominated in E. goffrilleri suggesting the presence of a considerable number of bacterial symbionts. The novel fatty acids (5Z,9Z)-2-methoxy-5,9-hexadecadienoic acid, (5Z,9Z)-2-methoxy-5,9-octadecadienoic acid, (5Z,9Z)-2-methoxy-5,9-nonadecadienoic acid, and (5Z,9Z)-2-methoxy-5,9-eicosadienoic acid are described for the first time in the literature. In addition, the iso-methyl-branched fatty acids (9Z)-2-methoxy-15-methyl-9-hexadecenoic acid and (5Z,9Z)-2-methoxy-15-methyl-5,9-hexadecadienoic acid, also identified in E. goffrilleri, were identified for the first time in nature. Based on the identified metabolites it is proposed that the unprecedented biosynthetic sequence: i-17:1Δ9 → 2-OMe-i-17:1Δ9 → 2-OMe-i-17:2Δ5,9 might be responsible for the biosynthesis of the novel iso-α-methoxylated fatty acids in E. goffrilleri.     

Distribution modes and possible origins of sheep wool hydrocarbons

An unusual mode of distribution of low-molecular-weight n-alkanes (C₁₁-C₁₅) with a slight even carbon-number predominance has been observed in the gas Chromatographic analysis of the paraffin fraction which was extracted from the wool of live sheep. This is in addition to the other two modes of medium-, C₁₅-C₂₄, and high-, C₂₄-C₃₃, molecular-weight alkanes usually present in wool wax which have also been found in sheep’s manure. The high-molecular-weight hydrocarbons (predominantly odd carbon-numbered) are presumed to be derived from the diet (pasture plants) whereas the other two hydrocarbon distributions probably result from the combined action of animal and microbial metabolism.     

Cuticular lipids of the booklouse,Liposcelis bostrychophila: hydrocarbons,aldehydes, fatty acids,and fatty acid amides

The booklouse, Liposcelis bostrychophila, is an increasingly common pest of stored food products worldwide. We report here the cuticular lipid composition of this pest (the first report of the hydrocarbons of any member of the Order Psocoptera and the first report of fatty acid amides as cuticular components for any insect). No unsaturated hydrocarbons were present. A homologous series of n-alkanes (C₂₁–C₃₄), monomethyl alkanes (3-, 4-, 5-, 7-, 9-, 11-, 12-, 13- and 15-methyl-) with a carbon chain range of C₂₈–C₄₂, and dimethyl alkanes (3, 7-; 9, 13-; 11, 15-; 13, 17-; 9, 21-; 11, 19-; and 13, 21-); with a carbon number range of C₃₁–C₄₃ were identified. The relative abundances of these hydrocarbons were low, comprising approximately 0.0125% of total biomass. The amides were a homologous series (C₁₆–C₂₂ in chain length), with the major amide being stearoyl amide. In addition to the amides, free fatty acids (C_16:1, C_16:0, C_18:2, C_18:1, and C_18:0 in chain length) and three straight chain aldehydes (C₁₅, C₁₆, and C_17:1 in chain length) also occurred as cuticular components. These findings are discussed in terms of the chemical and physiological ecology of this species.     

Polyunsaturated hydrocarbons in the stable fly

Three triply-unsaturated hydrocarbons were identified from cuticular lipids of male and mixed-sex stable flies,Stomoxys calcitrans. The major compound, (Z,Z)-1,7,13-pentacosatriene, and two minor compounds, (Z,Z)-1,7,13-tetracosatriene and (Z,Z)-1,7,13-tricosatriene, were synthesized. Samples of male and female stable flies that differed in age, seasonality, geographic origin, rearing conditions of adults, and methods of extraction were analyzed for the presence of these triolefins. Females were found to have small quantities of the same C₂₅ triolefin, which appeared to be identical to that in males. No evidence was seen for attraction of males or females to natural or synthetic triolefins.Mention of a proprietary or commercial product does not constitute an endorsement by either the U.S. Department of Agriculture or the University of Florida.