Richard A. I. Drew

Chemical studies of rectal gland secretions of some species ofBactrocera dorsalis complex of fruit flies (diptera: Tephritidae).

Male-produced rectal gland secretions of a number of species now considered to be members of theBactrocera dorsalis complex of fruit flies have been examined by combined gas chromatography-mass spectrometry. The structures of a number of previously unreported compounds have been confirmed by synthesis and Chromatographic comparisons. Compounds identified in these secretions include fatty acids, esters, amides, keto alcohols, diols and spiroacetals. These chemical findings are in agreement with taxonomic revisions based on other criteria.

Volatile compounds from the flowers of spathiphyllum Cannaefolium

Headspace analysis and solvent extraction of the pollenbearing flower spike of Spathiphyllum cannaefolium have been conducted by GC-MS, to determine the basis of the flower spike’s attractancy to certain fruit-fly species. The major components were benzyl acetate, methyleugenol, methylchavicol, p-methoxybenzyl acetate and fatty acids. Benzyl acetate is known to be attractive to D. cueurbitae, D. dorsalis and C. capitata (representing the three different ‘male-lure categories’) and methyleugenol (one of these male-lures) attracts D. cacuminatus, D. dorsalis and D. occipitalis. Thus the odoriferous flowerspike exhibits wide ranging attractancy and hence Spathiphyllum cannaefolium may have some application as a fruit-fly control measure for small orchards where ‘methyleugenol-attracted’ species (e.g. D. cacuminatus, D. dorsalis, D. occipitalis) are the dominant pests.

Chemistry of fruit flies: composition of the male rectal gland secretions of some species of South-East Asian Dacinae. Re-examination of Dacus cucurbitae(melon fly)

The major components of the rectal glandular secretions of male Dacus (Bactrocera) umbrosus(jack fruit fly), D. (Bactrocera) nigrotibialis, D. (Bactrocera) albistrigatus, D. (Zeugodacus) tau and D. (Zeugodacus) sp. (taxonomically similar to D. tau) have been identified. Alcohols, spiroacetals, and amides are the dominant components. The major component in the rectal gland secretion of Dacus (Zeugodacus) cucurbitae(melon fly) is shown to be ethyl 4-hydroxybenzoate and not 2-ethoxybenzoic acid.

Chemistry of fruit flies: Nature of glandular secretion and volatile emission ofBactrocera (bactrocera) cacuminatus (Héring)

The major component of the rectal glandular extract and volatile emission of maleBactrocera cacuminatus is racemic 1,7-dioxaspiro[5.5]undecane. l-Hydroxy-5-nonanone as its open chain form, together with 6-n-butyl-3,4-dihydro-2H-pyran are minor components. 1,7-Dioxaspiro[5.5]undecan-4-ol is present at a low level and is shown to be exclusively the diastereomer with an equatorial hydroxy group by comparison with synthesized samples of both epimers. Examination of the trifiuoroacetate by chiral gas chromatography has established the (4S,6S) stereochemistry (ca. 80% ee). The presence of 1,7-dioxaspiro[5.5]undecan-3-ol, or its isomerization product, 1,6-dioxaspiro[4.5]decan-2-ylmethanol, could not be confirmed. Trapping of the volatiles released by sexually mature male flies at dusk revealed that a number of the glandular components described above are released at mating time. Reexamination of the glandular secretion of sexually mature female olive flies (B. oleae) has failed to confirm the presence of any 1,7-dioxaspiro[5.5]undecanols, with the only volatile component (other than fatty acids) being 1,7-dioxaspiro[5.5]undecane.

An (S)-(+)-lactic acid route to (2S,6R,8S)-2,8 dimethyl-1,7-dioxaspiro[5,5]undecane and (2S,6R,8S)-2-ethyl-8-methyl-1,7-dioxaspiro[5,5]undecane and demonstration of their presence in the rectal glandular secretion of Bactrocera nigrotibialis(Perkins)

The chiral iodide resulting from reduction and iodination of the tetrahydropyran-2-yl ether of ethyl (S)-(+)-lactate has been engaged in a free-radical addition to acrylonitrile. The resulting protected hydroxy nitrite, on reaction with pent-4-enylmagnesium bromide afforded (S)-2-tetrahydropyran-2-yloxyundec-10-en-6-one. Oxymercuriation of this hydroxy enone, under reversible conditions, employing aqueous acid–tetrahydrofuran, effected simultaneous deprotection and cyclisation, and in situ biphasic demercuriation with sodium borohydride provided essentially stereochemically pure (2S,6R,8S)-2,8-dimethyl-1,7-dioxaspiro[5.5]undecane [i.e.the (E,E)-diastereoisomer only]. Epoxidation of the protected hydroxy enone, followed by dimethylcuprate ring-opening and cyclisation, provided a mixture of the (E,E)and the two possible (E,Z)-diastereoisomers of 2-ethyl-8-methyl-1,7-dioxaspiro[5.5]undecane with the former being the (2S,6R,8S) stereoisomer. Separation of the (E,E)from the two (E,Z)isomers was achieved by preparative gas chromatography. GC analysis of these samples and of the rectal glandular secretion of male Bactrocera nigrotibialis, using a cyclodextrin-based phase, demonstrated that the (2S,6R,8S)-stereoisomers of the 2,8-dimethyl- and 2-ethyl-8-methyl-1,7-dioxaspiro[5.5]undecanes were the natural products, with no detectable level of the antipodes.

Spiroacetals in rectal gland secretions of australasian fruit fly species

Combined gas chromatography–mass spectrometric examination of the rectal gland secretions of a number of Dacus species (Diptera: Tephritidae) having pest status in Australasia, has revealed the presence of a range of spiroacetals.

Chemistry of fruit flies: Glandular secretion ofBactrocera (Polistomimetes) visenda (Hardy)

The major component (>90% of volatiles) of the male rectal glandular extract of the nonpest speciesBactrocera visenda (Hardy) is 3-methyl2-butenyl acetate, with minor components being the isomeric 3-methyl-3-butenyl acetate, the homologous esters, 3-methyl-2-butenyl propanoate and 3-methyl-2-butenyl formate, along with 3-methyl-2-buten-1-ol, 3-methyl-2-butenal, and 3-methylbutyl acetate. None of these compounds has been identified previously from aBactrocera species, supporting the view thatBactrocera visenda is taxonomically distant from otherBactrocera species identified from the Australian mainland. This collection of compounds adds to the known types utilized by dipteran species and emphasizes their extensive biosynthetic capability.

Spiroacetals from dienones and hydroxyenones by mercury(II) cyclisation

Dienones and hydroxyenones are converted efficiently into spiroacetals by hydroxymercuration–cyclisation followed by either reductive or oxidative removal of mercury.