Opisthonotal Gland Research Articles

Neral (the Alarm Pheromone) Biosynthesis via the Mevalonate Pathway, Evidenced by D-Glucose-1-13C Feeding in Carpoglyphus lactis and 13C Incorporation into Other Opisthonotal Gland Exudates1

The monoterpene neral [(Z)-3,7-dimethyl-2,6-octadienal], an alarm pheromone, has been identified as a major component of the opisthonotal gland exudates of Carpoglyphus lactis, together with tridecane and (Z,Z)-6,9-heptadecadiene. The CDCl3 extract of mites fed D-glucose-1-13C for 30 days was found to have 13C atoms at positions 2, 4, 6 and 8–10 by 13C-NMR analysis. The compound neral was, therefore, concluded to be produced via the mevalonate pathway from 2-13C-acetyl-CoA by glycolysis. After seven days of feeding on D-glucose-1-13C, at least one 13C atom was incorporated in 51.6% of neral molecules. Likewise, 51.8% of tridecane, 42.5% of (Z,Z)-6,9-heptadecadiene, 39.5% of γ-acaridial and 33.4% of neryl formate, were also labeled, while squalene was not labeled, indicative of its origin, the culture medium.

Opisthonotal gland chemistry of a middle-derivative oribatid mite, Archegozetes longisetosus (Acari: Trhypochthoniidae)

Opisthonotal glands of sarcoptiform mites secrete a variety of compounds known to have defensive and pheromonal functions. We studied the gland chemistry of cultured individuals of the desmonomatan oribatid mite Archegozetes longisetosus Aoki (Trhypochthoniidae), to compare it with that of other oribatid mites and to examine in a preliminary way how the molting process may affect it. GC-MS analysis of hexane extracts of adult mites revealed three monoterpenes (geranial, neral, neryl formate), two aromatic compounds [γ-acaridial (3-hydroxybenzene-1,2-dicarbaldehyde) and 2,6-HMBD (2-hydroxy-6-methylbenzaldehyde)] and four hydrocarbons (pentadecane, pentadecene, heptadecene and heptadecadiene). In decreasing order, the most abundant compounds were γ-acaridial, neral, neryl formate and 2,6-HMBD, with the other five present only in minor or trace amounts. Active proto-, deuto- and tritonymphs have chemical profiles similar to that of adult mites. The same profile results when extracted nymphs are early in the pharate stage of molting, but probably they lose the ability to secrete as the molt progresses. Gland reservoirs from molted exuviae contain a similar secretion, which proves the origin of the hexane extracts. In larvae, and in adults disturbed for 30 min, neryl formate was usually the major compound detected. None of these compounds are unique among Trhypochthoniidae, and most are common in Astigmata, but the overall profile distinguishes A. longisetosus from other studied species.

Chemical Ecology of Astigmatid Mites. LXXI. Neryl Formate (Z)-3,7-Dimethyl-2,6-octadienyl Formate as The Alarm Pheromone of Tyroborus lini Oudemans 1924, and Its Recovery after Forced Discharge

The presence of the alarm pheromone was demonstrated in the hexane extract of an acarid mite Tyroborus lini Oudemans 1924. The active fraction derived from an SiO2 column chromatography of the mite extract was identified as neryl formate, (Z)-3,7-dimethyl-2,6-octadienyl formate by GC/MS and GC analysis. The synthesized neryl formate was shown to be active at 0.05–1 ng dose. Males contained 0.08 ng of the compound on average, and females 0.16 ng on average. The alarm pheromone was a component present in the opisthonotal gland. Once totally discharged from the gland upon disturbance, it took seven days before the pheromone content reached to its original level in the gland, whereas other compounds recovered within 60 hrs. The reason remains obscure at present.

Alpha-acaridial a female sex pheromone from an alarm pheromone emilting mite Rhizoglyphus robini.

The female sex pheromone of Rhizoglyphus robini Claparède (Astigmata: Acaridae) was identified as alpha-acaridial [2(E)-(4-methyl-3-pentenyl)-butenedial], which stimulated males sexually and enhanced the frequency of male mounting behavior. Although a hexane extract of females manifested alarm pheromone activity against tested males due to the presence of the alarm pheromone neryl formate, silica gel column fractions containing alpha-acaridial evoked increased mounting behavior by males at a dose of 0.1 female equivalent. Synthetic alpha-acaridial at a dose of 10 ng showed a peak of activity as a sex pheromone, with a convex dose-response relationship. Its content was determined to be 388 +/- 244 ng per female and 163 +/- 97 ng per male by GC. This is the first time that two pheromones (the alarm pheromone neryl formate, and the sex pheromone alpha-acaridial) have been demonstrated to be components of the same opisthonotal gland secretion in astigmatid mites. A mechanism for the appropriate expression of the two pheromones by the mites under different conditions is proposed.

(E)-2-(2-Hydroxyethylidene)-6-methyl-5-heptenal (alpha-acariolal) and (E)-2-(2-hydroxyethyl)-6-methyl-2,5-heptadienal (beta-acariolal), two new types of isomeric monoterpenes from Caloglyphus polyphyllae (Acari: Acaridae).

The opisthonotal gland secretion of the acarid mite, Caloglyphus polyphyllae, contained two new monoterpenes, (E)-2-(2-hydroxyethylidene)-6-methyl-5-heptenal (1) and (E)-2-(2-hydroxyethyl)-6-methyl-2,5-heptadienal (2), to which we have given the trivial names alpha- and beta-acariolal in relation to alpha- and beta-acaridial (3 and 4), respectively. Elucidation of the structure of 1 was established mainly from 1H-NMR and GC/MS spectral data after partial purification, together with the fact that 1 was recovered in the more-polar fraction from a silica gel column than alpha- and beta-acaridial (3 and 4) present in the secretion. Compound 2 was obtained in the same fraction as a mixture with 1. Based on the facts that 2 had the same molecular weight by GC/MS and the same polarity as that of 1, compound 2 was assumed to be a structural analog of 1. The structures of compounds 1 and 2 were confirmed by their synthesis in nine and ten respective steps starting from alpha-bromo-gamma-butyrolactone.

Chemical ecology of astigmatid mites. LXIV. The alarm pheromone neral functions as an attractant in Schwiebea elongata(Banks)(Acari: Acaridae).

Although neral [(Z)-3,7-dimethyl-2,6-octadienal] has been known as the alarm pheromone of Schwiebea elongata, reinvestigation of the pheromone resulted in recognition of another function as an attractant. The alarm pheromone activity was confirmed at a dose of one female equivalent of the hexane extract, whereas the attractant pheromone activity was observed at 0.1 female equivalent. Although no attractant activity was recovered in fractions of the silica gel (SiO2) column eluate, the synthetic neral manifested both activities; the attractant activity at 3 ng and 1 ng with a convex dose-response relationship, and the alarm pheromone activity at 30 ng. A female contained 30.4 ng of neral on average and a male 0.7 ng on average. This is the first example among astigmatid mites demonstrating that a single mite compound emitted from the opisthonotal gland exhibits two pheromonal functions, alarm pheromone and also attractant, at different doses.

Opisthonotal gland chemistry of early-derivative oribatid mites (Acari) and its relevance to systematic relationships of Astigmata

Mites of the suborder Astigmata produce a variety of chemicals – monoterpenes, aromatics and straight-chain hydrocarbons - in a pair of exocrine opisthonotal glands. The more common chemicals also are known from oribatid mites in Desmonomata. We used GC-MS to characterize hexane extracts of four earlier-derivative oribatid mite species. 1) Parhypochthonius aphidinus (in Parhyposomata, the most basal group with the gland): the major component is the aromatic 3-ethylphenol, with the hydrocarbons undecane and tridecene showing moderate peaks in GC profiles. 2) Gehypochthonius urticinus (also Parhyposomata): the major component appears to be an isomer of 1-methy1-2-naphthol, with heptadecadiene and 1-tridecene present in moderate abundance. 3) Nehypochthonius porosus (in Mixonomata): tridecane is usually the major component, with somewhat lesser amounts of an unidentified nonhydrocarbon component of molecular weight 150. 4) Perlohmannia sp. (a more derived mixonomatan): extracts contain pentadecene, the monoterpenes neral and geranial, and the aromatic γ -acaridial (2-formyl-3-hydroxybenzaldehyde). Hexane extracts from four outgroup taxa without opisthonotal glands – oribatid mites Hypochthonius rufulus, Eniochthonius sp., and endeostigmatic mites Lordalycus sp. and Bimichaelia sp. – have no detectable compounds. Considering nonhydrocarbons, all Perlohmannia gland components seem widely distributed in Astigmata, but those of earlier-derivative glandulate mites - P. aphidinus, G. urticinus and N. porosus - are not known from Astigmata. This chemical distribution is evidence that Astigmata evolved from within the oribatid mites, at some level above the earliest Mixonomata; it is therefore consistent with the hypothesis that Astigmata evolved within Desmonomata. At least in P. aphidinus, the gland probably has a role in predator defense; it seems quickly exhausted when mites are disturbed and its components are known irritants.

(4E)-dehydrocitrals [(2E,4E)- and (2Z,4E )-3,7-dimethyl-2,4,6-octatrienals] from acarid mite Histiogaster sp. A096 (Acari: Acaridae).

A mixture of two monoterpenes was obtained as the opisthonotal gland secretion from unidentified Histiogaster sp. A096 (Acari: Acaridae), and their structures were elucidated to be (4E)-dehydrocitrals [(2E,4E)- and (2Z,4E)-3,7-dimethyl-2,4,6-octatrienals] by GC/MS, GC/FT-IR, UV and 1H-NMR spectra. Both isomers of (4E)-dehydrocitral prepared by syntheses in 4 steps from 3-methyl-2-butenal with 34.2% yields (based on the ylide) were separated by column chromatography into the (2E,4E)- and (2Z,4E)-3,7-dimethyl-2,4,6-octatrienal. Mass spectra together with GC retention times of the purified natural (4E)-dehydrocitrals were identical with those of synthetic (2E,4E)-3,7-dimethyl-2,4,6-octatrienal and (2Z,4E)-3,7-dimethyl-2,4,6-octatrienal. The geometry at the 2-C position of both synthetic (4E)-dehydrocitrals was confirmed by NOESY analyses. This is the first identification of (4E)-dehydrocitrals from the animal kingdom.

Aggregation Pheromone Activity of the Female Sex Pheromone, β-Acaridial, in Caloglyphus polyphyllae (Acari: Acaridae).

Caloglyphus (=Sancasania) polyphyllae discharges from a pair of opisthonotal glands a characteristic set of volatiles, i.e. three monoterpenes and seven hydrocarbons. Among them, β-acaridial, which is known as the female sex pheromone of the species and has antifungal activity, was newly identified as the aggregation pheromone for unfeeding and unmating mites. Feeding mites, however, exhibited sexually aroused behavior instead of the tendency to cluster when exposed to β-acaridial. This is the first example of the compound demonstrating two pheromone functions depending upon the circumstances faced by the mites.

Structural elucidation of twelve novel esters composed of five fatty acids and three new branched alcohols together with four monoterpenoids from Sancassania shanghaiensis (Acari: Acaridae).

A total of 12 novel esters and four monoterpenoids (rosefuran, (2R,3R)-epoxyneral, and alpha- and beta-acaridials) were detected by GC/MS analyses as the opisthonotal gland components of Sancassania shanghaiensis. The acidic fraction after hydrolysis was composed of five common fatty acids (palmitic, stearic, oleic, linoleic and arachidic acid), while the alcoholic fraction consisted of two major components (C6 and C8 alcohols with branched methyls), together with a trace amount of C9 alcohol. The two major alcohols were identified as new alcohols [(S)-2-methylpentanol and (2S,4S)-2,4-dimethylhexanol] by comparing the physico-chemical data of their 3,5-dinitrobenzoates with those of regio-selectively synthesized alcohols. The C9 alcohol was suggested as (2S,4S)-2,4-dimethylheptanol, based on a structural and biogenetic analogy to the C6 and C8 alcohols. Five of the compounds were each identified by GC to be (S)-2-methylpentyl esters from five fatty acids, and the other five components likewise as (2S,4S)-2,4-dimethylhexyl esters. The remaining two were suggested as (2S,4S)-2,4-dimethylheptyl stearate and linolate.

(E)-2-(4'-Methyl-3'-pentenylidene)-4-butanolide, Named β-Acariolide: A New Monoterpene Lactone from the Mold Mite, Tyrophagus putrescentiae (Acarina: Acaridae).

Reinwestigation of the opisthonotal gland secretion of the mold mite, Tyrophagus putrescentiae, resulted in the isolation of a new monoterpene lactone, whose chemical structure was elucidated as (E)-2-(4'-methyl-3'-pentenylidene)-4-butanolide (3), to which we gave the trivial name β-acariolide in relation to β-acaridial {1, (E)-2-(4-methyl-3-pentenylidene)-butanedial}. The compound was synthesized by LiAlH3 (OEt) reduction of 1 and subsequent oxidation involving simultaneous cyclization by using Ag2CO3 on Celite. Both the E- and Z-isomers of β-acariolide (3 and 4) were also prepared by the reaction of α-ethoxaly-γ-butyrolactone (6) and 4-methyl-3-pentenal under basic conditions. Their NMR spectra were compared with each other, and the geometry of the pentenylidene double bond of the isolated compound was concluded as being E.

Chemical Ecology of Oribatid Mites. I. Oil Gland Components of Hydronothrus crispus Aoki.

The hexane extract of Hydronothrus crispus Aoki (Oribatida: Trhypochthoniidae) was analyzed by GLC and GC/MS using a capillary column and the following four compounds were identified as the non-hydrocarbon fraction; 2-hydroxy-6-methylbenzaldehyde, neral, geranial and neryl formate. The hydrocarbon fraction analysed based on GLC and GC/MS of their DMDS derivatives consisted of a mixture of tridecane, pentadecane, (Z) -7-pentadecene, (Z) -7-heptadecene, (Z) -8-heptadecene and (Z, Z) -6, 9-heptadecadiene. All the compounds found in the secretions of oribatid mite were commonly distributed as components of opisthonotal gland secretions from astigmatid mites.

2-Formyl-3-hydroxybenzyl Formate (Rhizoglyphinyl Formate), a Novel Salicylaldehyde Analog from the House Dust MiteDermatophagoides pteronyssinus[Astigmata, Pyroglyphidae

A novel salicylaldehyde analog was isolated in a 3.7% yield from the hexane extract of the acarid mite. Dermatophagoides pteronyssinus, possibly as its opisthonotal gland secretion. The chemical structure was physico-chemically elucidated to be 2-formyl-3-hydroxybenzyl formate, to which we give the trivial name rhizoglyphinyl formate, and the identity of the compound was confirmed by its synthesis.

Chemical Ecology on Astigmatid Mites : XXXI.Geranial as the Alarm Pheromone of Histiostoma laboratorium HUGHES(Astigmata:Histiostomidae)

Hexane extract derived from Histiostoma laboratorium HUGHES, possibly the opisthonotal gland secretion, contained hydrocarbons and monoterpene as major components. The monoterpene fraction indicated the alarm pheromone activity and consisted of a mixture of neral (10%, 3, 7-dimethyl-(Z)-2, 6-octadienal) and geranial (90%, 3, 7-dimethyl-(E)-2, 6 octadienal). The synthetic geranial was active at 1 ppm, while corresponding neral was inactive at 10 ppm. The alarm pheromone of Histiostoma laboratorium was, then, concluded as geranial. This is the first example that geranial is the active compound as the pheromone, although neral which is the other component of citral is well known as mite's alarm pheromone in at least 5 species.

Identification and synthesis of 2,3-epoxyneral, a novel monoterpene from the acarid mite Tyrophagus perniciosus (Acarina, Acaridae).

A novel monoterpene, 2(S), 3(S)-epoxy-3, 7-dimethyloct-6-enal (1), was isolated from the opisthonotal gland secretion of the mite Tyrophagus perniciosm, and was synthesized by asymmetric epoxidation of nerol with subsequent oxidation by pyridinium dichromate. The presence of this compound is a striking feature for chemical taxonomy since it has not been found in morphologically similar mites.

Chemical taxonomy of economically important Tyrophagus mites (Acariformes, Acaridae).

Rosefuran and perillene were isolated from the opisthonotal glands secretion of the Tyrophagus neiswanderi mite. A facile synthesis of the former was accomplished by the lithiation of 3-methyl- furan with butyllithium-tetramethylethylenediamine, and a subsequent reaction with 3-methyl-2- butenylbromide. A mixture of rosefuran, 4-methyl-2-(3-methyl-2-butenyl)-furan and 3-methyl-2,5-bis- (3-methyl-2-butenyl)-furan was obtained in a high yield. The occurrence of these and other recently identified monoterpenoids, namely, α- and β-acaridial and 2,3-epoxyneral, is discussed relative to the CP-Sil 19 CB column profiles as worthy for the identification of economically important mites of the genus Tyrophagus, which is a difficult but essential task for the successful application of the species-specific alarm pheromones in the management of these pests.

2(E)-(4-Methyl-3-pentenylidene)-butanedial, .BETA.-acaridial: A new type of monoterpene from the mold mite Tyrophagus putrescentiae (acarina, acaridae).

The natural product chemistry of opisthonotal gland excretion was studied for the mold mite Tyrophagus putrescentiae. The secretion contained a new type of monoterpene dial, 2(E)(4-inethyl-3-pentenylidene)-butanedial (1), which we gave the trivial name β-acaridial. The compound was synthesized by a Wittig reaction of 4-methyl-3-pentenyltriphenylphosphonium bromide with 1, 4-tetrahydropyranoxy-2-oxobutane (derived from the hydration of 2-butyn-l, 4-diol with HgSO4 and H2SO4, and subsequent protection of the hydroxy groups as tetrahydropyranoxy ether), deprotection of the hydroxy groups, and subsequent oxidation with PDC. The synthetic dialcohol was identical to β-acaridiol obtained by the reduction of the natural product.

Synthesis of dehydrocineole, a new monoterpene from the acarid mite, [formula omitted][formula omitted] (arachnida: acari)

Dehydrocineole, a new monoterpene ether, 6-methylsalicylaldehyde, undecane and tridecane are reported from the opisthonotal gland secretion of the mite, Caloglyphus rodriguezi . A synthesis of dehydrocineole is described.