Orbital Bristles Research Articles

Sarcophagidae (Insecta: Diptera) of Saudi Arabia: new records, an updated checklist and a new species.

As part of a study on the biodiversity of Diptera of south-western Saudi Arabia, a survey of the Diptera fauna of Jazan, Asir and Najran at 10 sites was performed between 20122015 mainly using Malaise traps, sweep nets and baited traps. A total of 21 species of Sarcophagidae are recorded and documented with photographs, seven of which represent new country records for Saudi Arabia. Including species with a reliable previous record from Saudi Arabia, the total number of species of Sarcophagidae known from Saudi Arabia now stands at 51. All species of Sarcophagidae recorded from Saudi Arabia are listed, including distributions and the source where species were first recorded. Material studied as part of the project resulted in 16 new country records for other countries. Alusomyia Villeneuve, 1933 is here synonymized with Hoplacephala Macquart, 1834, syn. nov., argued from the presence of four proclinate orbital bristles, the row of strong parafacial setae close to the anteroventral eye-margin, the large gena and the robust habitus compared to most other miltogrammines. The generic synonomy requires the new combinations Hoplacephala transfuga (Villeneuve, 1933), comb. nov. and Hoplacephala turana (Rohdendorf, 1975), comb. nov. Sarcophaga surcoufi Villeneuve, 1913 is synonymized with Engelisca adhamae Lehrer & Abou-Zied, 2008, syn. nov. An appendix authored by Dr J.C. Deeming contains the description of Sarcophaga dawahi Deeming, sp. nov.

PM 7/53 (2) Liriomyza spp.

PM 7/53 (2) <i>Liriomyza</i> spp.

Interplay between habitat fragmentation and climate change: inbreeding affects the response to thermal stress in Drosophila melanogaster

Climate change, exerting thermal stress, and habitat destruction and fragmentation, resulting in genetic drift and inbreeding, are amongst the most disturbing human activities that endanger global biodiversity. We studied the interplay between these 2 processes using Drosophila melanogaster as a model organism and investigated how inbreeding affects the response to thermal stress. We found that both inbreeding and thermal stress negatively affect morphological traits (orbital bristle number, wing width and wing length) as well as a fitness trait (egg-to-adult viability). Most importantly, we observed a significant interaction between inbreeding and thermal stress. Inbred populations suffered considerably more from thermal stress than non-inbred populations for these traits. Moreover, the variation among inbred populations was large: some populations were affected only slightly by thermal stress, but others became extremely sensitive to thermal stress, par- ticularly in egg-to-adult survival. This shows that inbreeding does significantly influence the response to thermal stress, thereby greatly enhancing the effects of temperature stress. We also tested if the effects of inbreeding and thermal stress were reflected in changes in the level of fluctu- ating asymmetry, in order to determine if this measure can be used as a reliable biomonitor. Although we observed some changes in fluctuating asymmetry under stress, the results are far from unequivo- cal. We concluded that inbreeding and thermal stress act synergistically and argue that the conse- quences of climate change and habitat fragmentation should preferably be studied in combination rather than in isolation.

Stability in development and variability in morphological signs in a natural population of Drosophila melanogaster: seasonal dynamics in 1999

Seasonal dynamics of developmental stability and variability of morphological traits was examined in a natural population of Drosophila melanogaster in order to compare these two parameters as indicators of temperature stress. Morphometric (thorax length and wing length) and meristic (number of sternopelural and orbital bristles) were studied. Variability was measured as the coefficient of variation. Stability of development was estimated as fluctuating asymmetry (FA) of bilateral traits. Thorax length and wing length did not exhibit consistent seasonal trends whereas wing loading significantly decreased. Significant seasonal changes in FA were not detected in any trait examined. Two traits showed reduced variation in autumn. The use of FA as an indicator of ecological stresses in insects is discussed on the basis of these results and the literature evidence.

Genetic Variability and Fluctuating Asymmetry of Morphological Traits in Drosophila melanogasterReared on a Pesticide-Containing Medium

The effects of chlorine-organic insecticide endosulfane (thiodan) on phenotypic and genetic variation in four morphological traits of Drosophila melanogaster(wing length, thorax length, the number of orbital bristles and the number of sternopleural bristles) were examined. In addition, the effect of this pesticide on stability of development measured as fluctuating asymmetry of bilateral traits was estimated. On the medium with endosulfane, phenotypic variation of morphometric traits was significantly higher. No difference in fluctuating asymmetry between the stressed and the control samples was found. The among-line variance of morphometric traits of flies reared on the endosulfane-containing medium was significantly higher as compared to the corresponding variance under control conditions. The efficiency of using fluctuating asymmetry and phenotypic variation of morphometric and meristic traits as indicators of environmental stress in insect populations is discussed.

THE ASSOCIATION BETWEEN FLUCTUATING ASYMMETRY, TRAIT VARIABILITY, TRAIT HERITABILITY, AND STRESS: A MULTIPLY REPLICATED EXPERIMENT ON COMBINED STRESSES IN DROSOPHILA MELANOGASTER.

A number of hypotheses have been proposed about the association between developmental stability phenotypic variability, heritability, and environmental stress. Stress is often considered to increase both the asymmetry and phenotypic variability of bilateral traits, although this may depend on trait heritability. Empirical studies of such associations often yield inconsistent results. This may reflect the diversity of traits and conditions used or a low repeatability of any associations. To test for repeatable associations between these variables, multiply replicated experiments were undertaken on Drosophila melanogaster using a combination stress at the egg, larval and adult stages of reduced protein, ethanol in the medium, and a cold shock. Both metric and meristic traits were measured and levels of heritable variation for each trait estimated by maximum likelihood and parent-offspring regression over three generations. Trait means were reduced by stress, whereas among-individual variation increased Fluctuating asymmetry (FA) was increased by stress in some cases, but few comparisons were significant. Only one trait orbital bristle, showed consistent increases in FA. Changes in trait means, trait phenotypic variability, and developmental stability as a result of stress were not correlated. Extreme phenotypes tended to have higher levels of FA but only the results for orbital bristles were significant. All traits had low to intermediate heritabilities except orbital bristle, which showed no heritable variation. Only traits with low heritability and high levels of phenotypic variability may show consistent increases in FA under stress. Overall, the independence of phenotypic variability, plasticity, and the developmental stability of traits extend to changes in these measures under stressful conditions.

Electron microscope investigation of polytene chromosomes in the Mediterranean fruit fly Ceratitis capitata.

Ultrastructural analyses of polytene chromosomes from male pupal orbital bristle cells and from larval salivary glands of Ceratitis capitata were carried out. It was shown that chromatin complexes corresponding to the X chromosome heterochromatic network are surrounded by material containing ribonucleoprotein (RNP) granules 250-300 A (1 A = 0.1 nm) in diameter. RNP granules of similar size surround the spherical Y chromosome. These data point out the presence of transcriptional activity in both of these chromosomes. The absence of clear structure in chromosomal regions situated between large bands in both types of tissues was observed. These results support the hypothesis of weak synapsis between chromatids or small chromomeres of polytene chromosomes in this species. In addition, we describe a specific puff revealed in both orbital trichogen cells and salivary glands that is morphologically similar to the 93D puff of Drosophila melanogaster.

"Cut-bristles" : a sex-limited mutant phenotype of male orbital bristles of Ceratitis capitata

"Cut-bristles" : a sex-limited mutant phenotype of male orbital bristles of Ceratitis capitata

"Cut-bristles": a sex-limited mutant phenotype of male orbital bristles of Ceratitis capitata

"Cut-bristles": a sex-limited mutant phenotype of male orbital bristles of Ceratitis capitata

A comparison of polytene chromosomes in salivary glands and orbital bristle trichogen cells in Ceratitis capitata

The banding patterns of polytene chromosomes in different tissues of the Mediterranean fruit fly, Ceratitis capitata, vary to such an extent that homologous chromosomes cannot be recognised. However, analyses of autosomal breakpoints in several translocation strains allowed chromosomes from the two tissues to be aligned despite their difference in banding pattern. These results were discussed, considering the different hypotheses of the origin and biological significance of polytene chromosome bands.Key words: polytene chromosomes, salivary gland chromosomes, orbital bristle trichogen cell chromosomes, Ceratitis capitata.

Cytogenetic analysis of three genetic sexing strains of Ceratitits capitata

Polytene chromosomes of three genetic sexing strains of Ceratitis capitata were analyzed. The genetic sexing mechanism is based on a pupal color dimorphism (white-brown) and is the result of a reciprocal translocation between the Y chromosome and the autosome bearing the w locus (white pupal case). The analyzed polytene chromosomes were derived from two different pupal tissues, the orbital bristle and fat body cells. The Y chromosome is visible in both tissues, while the autosomes present a different banding pattern. Based on these features, the autosome breakpoints in the three Y; autosome translocations were mapped, and the homology of the translocated autosome in both tissues was established. In addition, the location of the break-points was compared to the stability of these three strains.

Polytene chromosome mapping in Ceratitis capitata (Diptera: Tephritidae)

Polytene chromosome reference maps of the five autosomes of Ceratitis capitata from male pupal orbital bristle trichogen cells are presented and a correlation is established between two of them and the two largest of the five autosomes in the haploid mitotic complement. Characteristic features of each chromosome are described identifying areas that are difficult to analyze and noting the existence of common alternative band expression. A quantitative analysis of the mitotic karyotype of C. capitata indicates that the two smallest autosome pairs cannot be reliably distinguished. This may present problems with future attempts to establish homologies between the remaining mitotic and polytene chromosomes. A comparison of polytene chromosome banding patterns from salivary gland and trichogen cells failed to find any homologous regions, or even to identify homologous chromosomes. The banding differences are not explained by variation in puffing patterns, heterochromatin expression, or polyteny levels, but appear to reflect fundamental differences in banding patterns of the chromosomes in each tissue. Key words: Ceratitis capitata, polytene chromosome map, mitotic chromosome measurements.

Polytene and mitotic chromosome analysis in Ceratitis capitata (Diptera; Tephritidae)

Polytene chromosomes were found in several larval and pupal tissues of the Medfly, Ceratitis capitata, during a search for chromosomes suitable for detailed cytological analysis. Well-banded highly polytene chromosomes, which could be adequately separated and spread, were found in trichogen cells of the spatulate superior orbital bristles of male pupae. These chromosomes proved suitable for full polytene analysis. Thoracic trichogen cells of both male and female pupae also contain useful polytene chromosomes, although they are considerably thinner and thus more difficult to analyze. Contrasting with those in pupal trichogen cells, the chromosomes in the salivary glands, Malphighian tubules, midgut, hindgut, and fat body of larvae and pupae were difficult to prepare because of high levels of ectopic pairing and chromosome fragmentation. In hindgut preparations partial separation of up to three chromosomes was achieved, but in all other tissues no useful chromosome separation was possible. In trichogen polytene cells, five banded chromosomes and a prominent heterochromatic network associated with a nucleolus are found. The mitotic chromosomes respond to C- and Q-banding and silver staining with considerable variation. This is especially so in the X chromosome, which displays an extensive array of bands following both Q-banding and silver staining. Comparison of Q-banded metaphase and polytene chromosomes demonstrates that the five autosomes are represented by conventional polytene chromosomes, while the sex chromosomes are contained in the heterochromatic net, most of which fluoresces strongly. This suggests that the Q-bands of the mitotic X chromosome are replicated to a greater extent than the nonfluorescent material in polytene cells. This investigation shows C. capitata to have excellent cytological material for both polytene and mitotic analysis.Key words: Ceratitis capitata, Medfly, chromosomes (polytene), banding (chromosome).

Four new African Mosquitos

♀. Head clothed almost entirely with broad flat scales, though there are a very few narrow curved ones and a few upright forked ones on the nape. Scales at the back of the head mostly light ochreous; a rather broad creamy mid-dorsal stripe, and a conspicuous silvery margin to the eyes; remaining scales on upper part of head forming two large but irregular patches of black; another small black patch low down among the creamy scales on each side. Clypeus bare, dark brown. Eyes well separated. Orbital bristles dark brown. Proboscis blackish, slender, slightly longer than the front femora. Palpi fully one-fourth as long as the proboscis, blackish, with the usual conspicuous silvery apical patch. Tori blackish, with a large patch of silvery-white scales. Thorax with the integument uniformly black. Mesonotum clothed mainly with rather large and coarse, dull brown, narrow, curved scales, those surrounding the ante-scutellar space golden-brown, but scarcely any broader than the others, and not forming definite lines; no mid-dorsal golden line; a small patch of board flat silvery scales in the middle of the front margin, and a small patch of narrower scales in front of the root of each wing; a pair of large crescent-shaped patches of broadly crescent-patches of broadly crescent-shaped silvery-white scales in the anterior half. Scutellum with the median and lateral bodies lobes completely clothed with silvery scales. Prothoracic lobes, pro-epimera bristles, and a large part of the pleurae clothed with silvery-white scales. About five pro-epimeral bristles, and about five post-spiracular; no lower mesepimeral. Abdomen clothed mostly with purplish-black scales; the first tergite, and a basal band on each of tergite, 2–7, creamy white; all tergites with large silvery basal lateral spots, and sternites with silvery basal bands. Eighth segment rather prominent; cerci very short. Legs rather slender. Front femora almost entirely black; mid fermora black except for a small white spot on the anterior side just beyond the middle, and a rather conspicuous silvery-white tip; hind femora all white on the basal fourth, the outer side silvery-white to a little beyond the middle and also rather broadly at the tip. Front and middle tibiae with a small white spot at the base beneath, hind tibiae entirely black. Front and middle tarsi black, with narrow white rings at the bases of the first two segments; hind tarsi with rather narrow white rings at the bases of the first three segments, fourth segment white except for the extreme tip, fifth all black. Front and middle claws toothed; hind simple. Wings normal, the scales ligulate and rather dense. Wing-length 4 mm.

NEW TACHINIDÆ WITH A SLENDER PROBOSCIS

The Tachinidæ described below have a slender, rigid proboscis, of which the portion beyond the basal articulation is at least one half longer than the height of the head. All are from the Pacific Coast, and, except where otherwise stated, were captured or bred by the writer.Siphona plusiœ,n. sp.—♂ ♀ Terminal section of proboscis—the part beyond the second geniculation—not more than three-fourths as long as height of head. Frontal vitta yellow, less than twice as wide as either side of the front next the antennæ; sides of front grayish pollinose, frontal bristles descending nearly to apex of second antennal joint, two pairs of orbital bristles; face whitish, the sides bare; vibrissæ inserted near the oral margin, only two or three small bristles above each; cheeks less than one-fourth as wide as height of eyes.