4,6,8,10,16-Penta- and 4,6,8,10,16,18-hexamethyldocosanes from the cane beetle Antitrogus parvulus - Cuticular hydrocarbons with unprecedented structure and stereochemistry

The major cuticular hydrocarbons from the cane beetle species Antitrogus parvulus were deduced to be 4,6,8,10,16,18-hexa- and 4,6,8,10,16- pentamethyldocosanes 2 and 3, respectively. Isomers of 2,4,6,8-tetramethylundecanal 27, 36, and 37, derived from 2,4,6-trimethylphenol, were coupled with the phosphoranes 28 and 29 to furnish alkenes and, by reduction, diastereomers of 2 and 3. Chromatographic and spectroscopic comparisons confirmed 2 as either 6a or 6b and 3 as either 34a or 34b.

Cuticular Hydrocarbons of Buffalo Fly, Haematobia exigua, and Chemotaxonomic Differentiation from Horn Fly, H.irritans

We determined the quantity and chemical composition of cuticular hydrocarbons of different strains, sex and age 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 produced 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 buffalo flies. Cuticular hydrocarbons of buffalo flies are distinctly different from those of horn flies. The most noticeable differences were in the C23 alkenes, with the major isomers 11- and 7-tricosene in buffalo flies and (Z)-9- and (Z)-5-tricosene in horn flies, respectively. Cuticular hydrocarbon analysis provides a reliable method to differentiate buffalo and horn fly, which are difficult to separate morphologically. The differences in cuticular hydrocarbons also support their recognition as separate species, H. exigua and H. irritans, rather than as subspecies.

Diverse cuticular hydrocarbons from Australian canebeetles (Coleoptera: Scarabaeidae)

Cuticular hydrocarbon components in beetles of six Australian melolonthines whose larvae damage sugarcane, Antitrogus parvulus (Britton), A. consanguineus (Blackburn), Lepidiota negatoria (Blackburn), L. picticollis (Lea), L. noxia (Britton) and Dermolepida alborhirtum (Arrow), are identified and compared. These species demonstrate species-specific cuticular hydrocarbon profiles with a number of unprecedented structures. Major components have been identified as polymethylated hydrocarbons, 3-methyl substituted n-alkanes, 9,10-allenes and the corresponding C9 alkenes. The similarity of these compounds shows some correlation with the phylogeny of the beetles, but two polymethylated C22 hydrocarbons are unique to A. parvulus. One C25 allene is shown to have a potential role in mate recognition in A. consanguineus.

Essential Oil Composition of Diploid and Tetraploid Clones of Ginger (Zingiber officinale Roscoe) Grown in Australia

Ginger oil, obtained by steam distillation of the rhizome of Zingiber officinale Roscoe, is used in the beverage and fragrance industries. Ginger oil displays considerable compositional diversity, but is typically characterized by a high content of sesquiterpene hydrocarbons, including zingiberene, arcurcumene, â-bisabolene, and â-sesquiphellandrene. Australian ginger oil has a reputation for possessing a particular “lemony” aroma, due to its high content of the isomers neral and geranial, often collectively referred to as citral. Fresh rhizomes of 17 clones of Australian ginger, including commercial cultivars and experimental tetraploid clones, were steam distilled 7 weeks post-harvest, and the resulting oils were analyzed by GC-MS. The essential oils of 16 of the 17 clones, including the tetraploid clones and their parent cultivar, were found to be of substantially similar composition. These oils were characterized by very high citral levels (51-71%) and relatively low levels of the sesquiterpene hydrocarbons typical of ginger oil. The citral levels of most of these oils exceeded those previously reported for ginger oils. The neral-to-geranial ratio was shown to be remarkably constant (0.61 ( 0.01) across all 17 clones. One clone, the cultivar “Jamaican”, yielded oil with a substantially different composition, lower citral content and higher levels of sesquiterpene hydrocarbons. Because this cultivar also contains significantly higher concentrations of pungent gingerols, it possesses unique aroma and flavor characteristics, which should be of commercial interest.

The suitability of plantation thinnings as vineyard posts.

The aim of this project was to investigate the suitability of thinnings from a range of plantation species for use as vineyard posts. The hardwood plantation species examined were Eucalyptus grandis, E. globulus, E. pilularis, E. dunnii, E. cladocalyx and Corymbia maculata, while Acacia mearnsii was obtained from natural regrowth. The softwood plantation species were P. elliottii, P. radiata and Araucaria cunninghamii. Variables examined included: three air drying regimes; microwave conditioning of E. grandis and E. globulus; two preservative treatments for hardwoods (alkaline copper quaternary compound (ACQ) and pigment emulsified creosote (PEC)); and two preservative treatments for softwood species (ACQ and, for Pinus radiata copper chromium arsenic (CCA)). A further aim was to install treated posts in commercial vineyards for demonstration purposes. From an earlier trial of three hardwood species treated with PEC, demonstration posts previously installed were also to be inspected annually for three years, and any movement of polycyclic aromatic hydrocarbons (PAH) from the posts monitored.