Manual for Diagnosis of Screw-worm Fly - xcs consulting

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Agriculture, Fisheries and Forestry - Australia Figure 31: Morphological differences between geographical races of Chrysomya bezziana. 47
A Manual for the Diagnosis of Screw-Worm Fly 7.3 Chemical (by Dr W.V. Brown) Introduction Many diagnostic laboratories, universities and research institutes operate a gas chromatograph for analytical studies. The gas chromatograph can be used to detect chemical differences between different insect species. The surface lipids (hydrocarbons) on the cuticle of insects protects them against dessication and invasion of pathogenic organisms and harmful substances. The chemical characterisation and quantification of hydrocarbons in insects has shown that they can be a useful chemotaxonomic character. They have been used to distinguish otherwise morphologically identical species and even sub-species and geographical races of the same species. Profiles can be generated from parts of a single fly (e.g. thorax alone). C. bezziana and C. hominivorax adults can be readily distinguished and separated from morphologically similar blowflies associated with the two SWF species, using cuticular hydrocarbon profiles (Fig. 32). Nevertheless, differences in hydrocarbon profiles within a species do occur (due to age and sex) and, as with every other taxonomic character, care must be exercised in interpreting results (Brown, et al. 1998). Preparation of samples Individual flies (or parts thereof) are put in small test tubes and just covered with hexane (liquid chromatography grade). After ten minutes the hexane is removed and introduced to the top of a 5cm column of Bio-sil A (100-200 mesh, Bio-Rad) in a pasteur pipette. The extraction is repeated 3 times. The hydrocarbons are then eluted with a further 2-3ml of hexane. The solvent is removed at room temperature under a stream of nitrogen. Hexane (50 µl) is then added and ca 2 µl of the resulting solution injected for gas chromatography. Unsaturates can be detected readily by treatment of a sample with a little bromine followed by rechromatography with any alkenes selectively removed. Gas chromatography At CSIRO Division of Entomology, gas chromatography (GC) is performed on a Varian model 3300 capillary gas chromatograph filled with a cool on-column injector and a flame ionisation detector. The data system used is an Epson PCe computer with an AD converter and Data Acquisition, Plotting and Analysis software. The column is a DB1 bonded phase methyl silicone column (30m x 0.32mm, film thickness 0.25µm, J&W Scientific). Injection is done at 60º, the temperature is then raised rapidly to 220º followed by programming at 4º/min to 310º with a hold at this temperature for 15min. Helium (1.5ml/min) is the carrier gas. Mass spectrometry Mass spectra are determined on a VG Micromass 70-70F mass spectrometer interfaced directly to a Hewlett-Packard 5792A capillary gas chromatograph and a VG 11-250 data system. GC conditions are similar to those above. Electron ionisation mass spectra are obtained at an ionisation voltage of 70eV and a source temperature of 200º. The mass spectra in conjunction with GC retention data (equivalent chain length, ECL) are used to determine the chemical identity of the individual hydrocarbons (Lockey, 1988). 48
Page 1 and 2:
A Manual for the Diagnosis of J.P.
Page 3 and 4: © Commonwealth of Australia 2002 R
Page 5 and 6: A Manual for the Diagnosis of Screw
Page 8 and 9: 1. Introduction Agriculture, Fisher
Page 10 and 11: The predicted distribution of C. be
Page 12 and 13: Figure 4: Life cycle of the Old Wor
Page 14 and 15: 2.4 Larval development 7 Agricultur
Page 16 and 17: 2.5 Pupariation Within 24 hours (at
Page 18 and 19: The egg of C. bezziana is white, 1.
Page 20 and 21: Figure 12: Details of larval morpho
Page 22 and 23: 4- Myiasis: Differential Diagnosis
Page 24 and 25: 5. Flies causing myiasis The follow
Page 26 and 27: Agriculture, Fisheries and Forestry
Page 28 and 29: 21 Agriculture, Fisheries and Fores
Page 30 and 31: Figure 15: Eggs of several species
Page 36 and 37: Figure 17 (contd): Morphology of th
Page 38 and 39: Figure 19: Cochliomyia hominivorax
Page 40 and 41: Figure 21: Chrysomya megacephala th
Page 42 and 43: Figure 23: Chrysomya rufifacies thi
Page 44 and 45: Figure 25: Chrysomya varipes third
Page 46 and 47: Figure 27: Lucilia species third in
Page 48 and 49: 6.3 Puparia Agriculture, Fisheries
Page 50 and 51: 7. Keys to adults 7.1 Morphological
Page 52 and 53: 45 Agriculture, Fisheries and Fores
Page 56 and 57: Hydrocarbon content (Table 1) Chrys
Page 58 and 59: Cochliomyia macellaria Agriculture,
Page 60 and 61: 8. Surveillance While SWF remains o
Page 62 and 63: Screw-worm fly sticky trap design a
Page 64 and 65: 8.3 Sentinels (Fig. 35, Plate 8) Ag
Page 66 and 67: 9. Acknowledgements Agriculture, Fi
Page 68 and 69: Lockey, K.H (1988). Lipids of the i
Page 70: Plate One. LIFE CyCLE OF SCREW-WORM
Page 74: Plate Three. Plate page Agriculture
Page 78: Plate Five. Plate page Agriculture,
Page 82: Plate Seven. ADuLT FLIES Plate page
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