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At least 145 records · Page 8Linked to original sources
PubMed2005

Validation of a DNA-based method for identifying Chrysomyinae (Diptera: Calliphoridae) used in a death investigation.

Many authors have proposed DNA-based methods for identifying an insect specimen associated with human remains. However, almost no attempt has been made to validate these methods using additional observations. We tested a protocol for identifying insects in the blow fly subfamily Chrysomyinae (Diptera: Calliphoridae) often found to be associated with a human corpse in Canada or the USA. This method uses phylogenetic analysis of DNA sequence from a short segment of the mitochondrial gene for cytochrome oxidase one (COI). Test chrysomyine COI sequences were obtained from 245 newly sequenced specimens and 51 specimens from the published literature. Published sequences from representatives of nonchrysomyine genera were also included to check for the possibility of a false positive identification. All of the chrysomyine test haplotypes were correctly identified with strong statistical support, and there were no false positives. This method appears to be an accurate and robust technique for identifying chrysomyine species from a death investigation in this geographic region. The far northern species Protophormia atriceps was not evaluated; therefore, caution is required in applying this method at very high latitudes in North America.

Animals↗
PubMed2001

An initial study on the succession of sarcosaprophagous Diptera (Insecta) on carrion in the southeastern Iberian peninsula.

We present the results of the first study concerning Diptera carried out on the sarcosaprophagous fauna of southeastern Spain. This work represents the first attempt to describe dipteran sarcosaprophagous fauna in the Iberian peninsula, the seasonal succession, main features of the population dynamics and the main taxa useful for estimation of the post-mortem interval. The results of this study could be very useful for further forensic case work in the west Mediterranean area.

Animals↗
PubMed2005

A conserved trans-regulatory landscape for scute expression on the notum of cyclorraphous Diptera.

Bristles on the notum of many cyclorraphous flies are arranged into species-specific stereotyped patterns. The positions of bristles correlate with differences in the spatial expression of the scute (sc) gene in those species examined so far. However, a major upstream activator of scute, Pannier (Pnr), is expressed in a conserved domain over the entire medial notum. Here we examine the expression patterns in Calliphora vicina of stripe (sr), u-shaped (ush), caupolican (caup) and wingless (wg), genes known to modify the activity of Pnr or to act downstream of Pnr in Drosophila. We find that, with minor differences, their expression patterns are conserved. This suggests that the function of a trans-regulatory network of genes is relatively unchanged in derived Diptera and that many differences are likely to be due to changes in cis-regulatory sequences of scute.

Animals↗
PubMed2006

Conservation of upstream regulators of scute on the notum of cyclorraphous Diptera.

Bristles on the notum of many cyclorraphous flies are arranged into species-specific stereotyped patterns. Differences in the spatial expression of the proneural gene scute correlate with the positions of bristles in those species looked at so far. However, the examination of a number of genes encoding trans-regulatory factors, such as pannier, stripe, u-shaped, caupolican and wingless, indicates that they are expressed in conserved domains on the prospective notum. This suggests that the function of a trans-regulatory network of genes is relatively unchanged in derived Diptera, and that many differences are likely to be due to changes in cis-regulatory sequences of scute. In contrast, in Anopheles gambiae, a basal species with no stereotyped bristle pattern, the expression patterns of pannier and wingless are not conserved, and expression of AgASH, the Anopheles proneural gene, does not correlate in a similar manner with the bristle pattern. We discuss the possibility that independently acting cis-regulatory sequences at the scute locus may have arisen in the lineage giving rise to cyclorraphous flies.

Animals↗
PubMed1996

Tympanal hearing in tachinid flies (Diptera, Tachinidae, Ormiini): the comparative morphology of an innovation.

Tympanal hearing organs have been reported only recently for Diptera. All the cases documented so far relate to parasitoid tachinid flies of the ormiine tribe. In the ormiine flies, the presence of tympanal hearing is functionally linked to their reproductive behavior. Indeed, female ormiine flies detect and localize their host, typically singing orthopterans, by hearing their calling songs. The three ormiine fly species investigated here at the comparative level share the key morphological features associated with tympanal hearing. The extent of these structural modifications becomes evident in the light of comparison with the closely related atympanate tachinid Myiopharus doryphorae. We document a series of eight characters that constitute specialized modifications of the ventral prothorax: (1) an inflation of the probasisternum, providing a rigid frame to span the large tympanal membranes; (2) an increased surface area of the prosternal membranes that constitute very thin, corrugated tympanal membranes; (3) a forked, broad presternum with tympanal pits to which the sensory organs directly attach; (4) several modifications of the tracheal system comprising the enlargement of the prosternal air sac, a supplementary tracheal tube to the prosternal air sac accompanied by a subpartioning of the spiracular atrium, and larger mesothoracic spiracles; (5) the presence of two scolopophorous chordotonal organs in the unpartitioned prosternal air sac; (6) stiff cuticular apodemes linking the chordotonal organs to the presternum; (7) reduction in size of the cervical sclerites; and (8) several structural modifications of the prosternal apophyses, creating new attachment sites for neck muscles. This comparative approach brings out differences and similarities of the homologous cuticular structures found on the ventral prothorax of both tympanate and atympanate tachinids. It is proposed that, given the degree of similarity between the ormiine hearing organs, the ormiine tribe is monophyletic, whereby all members of this tribe evolved from a common ancestor, an acoustic parasitoid of a singing orthopteran insect.

Animals↗
PubMed2005

Development and reproduction of Stratiolaelaps scimitus (Acari: Laelapidae) with fungus gnat larvae (Diptera: Sciaridae), potworms (Oligochaeta: Enchytraeidae) or Sancassania aff. sphaerogaster (Acari: Acaridae) as the sole food source.

Stratiolaelaps (=Hypoaspis) miles (Berlese) (Acari: Mesostigmata: Laelapidae) is a polyphagous soil-dwelling predatory mite that is widely marketed for use in greenhouse production systems to manage populations of dark-winged fungus gnats, Bradysia spp. (Diptera: Sciaridae) and for supplemental control of thrips. The suggestion by Walter and Campbell (2003, Biol. Control 26: 253-269) that North American commercial cultures of S. miles may actually be S. scimitus was confirmed. The development and reproduction at 21-23 degrees C of S. scimitus provided ad libidum with one of three different prey--the fungus gnat Bradysia aff. coprophila (Lintner), potworms (Enchytraeidae), or Sancassania aff. sphaerogaster (Zachvatkin, 1937) (Acari: Astigmata: Acaridae)--were compared. Developmental duration of the egg and non-feeding larval stages were 2.47 and 1.11 days, respectively; mortalities were 8.3 and 5.5%. Stratiolaelaps scimitus failed to develop beyond the protonymphal stage when provided with S. aff. sphaerogaster alone, although some feeding was observed. Development and reproduction of S. scimitus was successful on both fungus gnat larvae and enchytraeids, with no influence of prey on protonymphal duration (4.70 days) and mortality (8.3%), or on deutonymphal duration (4.61 days) and mortality (6.1%). Adult female S. scimitus feeding on potworms, compared to those feeding on fungus gnat larvae, had a significantly shorter pre-oviposition period (2.69 vs. 4.59 days). However, diet did not influence other adult female developmental or reproductive characteristics (oviposition period, 18.6 days; post-oviposition period, 6.2 days; total adult longevity, 27.3 days; total number of eggs, 26.5). S. scimitus reared on potworms tended (p = 0.06) to have a higher intrinsic rate of increase, a higher finite rate of increase and a shorter doubling time (rm = 0.142 day(-1), lambda = 1.153, Dt = 4.85 days) than those reared on fungus gnat larvae (rm = 0.105 day(-1), lambda = 1.110, Dt = 6.58 days), but differences in net reproductive rate (R0) and generation time (G) were not significant.

Acari↗
PubMed2006

The effects of temperature shock on transcription and replication in Rhynchosciara americana (Diptera: Sciaridae).

The chromosomal response to temperature shock in Rhynchosciara americana is similar to that observed in other Diptera. After a 33 degrees C/90 min or a 36 degrees C/30 min shock the reaction for RNA polymerase II (RpII) is enhanced at five loci. The most prominent of these was identified by in situ hybridization as the site of the hsp70 gene. At 33 degrees C, an accumulation of heat shock factor (HSF) and an increase in the level of RpII was observed at some heat shock loci after 5 min and reached a maximum after 15 min at most loci. The pattern of accumulation of HSF and RpII at individual heat shock loci was similar and their increases were generally coordinated among the loci. RpII gradually decreased at sites active prior to shock, the rate of decrease varying with the site. The B2 DNA puff retained RpII for a significant length of time while the histone locus still contained RpII after a shock of 90 min. With a 36 degrees C/30 min shock, the size of the heat shock puffs and the intensities of HSF and RpII peaked at 1-4 h post stress. The level of HSF declined rapidly after 1 h while the level of RpII remained high for an additional 4 h. The reaction of the DNA puffs to heat shock varied. Usually they did not regress completely and retained traces of RpII. BrdU incorporation continued at both amplifying and non-amplifying bands after shock but on average it appeared depressed for about 24 h post stress.

Animals↗
PubMed2006

Oviposition in Delia platura (Diptera, Anthomyiidae): the role of volatile and contact cues of bean.

The choice of a suitable oviposition site by female insects is essential for survival of their progeny. Both olfactory and contact cues of the oviposition site may mediate this choice. The polyphagous Delia platura (Diptera: Anthomyiidae), a severe agricultural pest of numerous crops, lays eggs in the soil close to germinating seeds. Maggots feed upon the cotyledons. Only little is known about the cues guiding oviposition behavior. In this study, the effects of both olfactory and contact cues of beans (Phaseolus vulgaris) on oviposition of D. platura females were tested. Egg deposition on germinated beans was preferred to egg deposition on ungerminated beans or on beans in different postgerminating developmental stages. Olfactory cues of germinating beans alone stimulated female flies to lay eggs. Additional contact cues of germinating beans seemed to enhance the response, but the difference was not significant. Surface extracts of germinating beans sprayed on surrogate beans showed that both polar and nonpolar substances stimulated oviposition of D. platura flies. Gas chromatography-electroantennographic detection recordings of head space samples of germinating beans showed positive response of females to different compounds. We conclude that olfaction plays a major role when D. platura females are searching for oviposition sites. Volatile compounds released from germinating beans such as 4-hydroxy-4-methyl-2-pentanone, 1-hepten-3-one, 1-octen-3-ol, and 3-octanone should be considered as key compounds that mediate oviposition behavior. The use of different sensory modalities by closely related species of Delia is discussed.

Animals↗
PubMed1990

A sequence-specific protease cleaves a maternal, cortical protein during early embryogenesis in Sciara coprophila (Diptera).

One of the first events of egg activation in Sciara coprophila (Diptera) is the disappearance of an abundant maternal 38-kDa protein (p38) and the simultaneous emergence of an abundant 35-kDa protein (p35). Western blotting experiments using monoclonal antibodies directed against p38 reveal that p38 and p35 are serologically related and indicate that maternal p38 is transformed into p35 during early development. This transition is possibly accompanied by a conformational change in the part of the protein that is common to both protein species. The processing of p38 to p35 can be mimicked by trypsin treatment in vitro, suggesting that a trypsin-like protease is responsible for this conversion in vivo. Immunostaining indicates that the p38 class of antigens is evenly distributed in the periplasm of early cleavage embryos. After the arrival of nuclei in the periplasm, the antigens become associated with the infolding cellular membranes. A similar membrane association of actin can be observed with anti-actin antibodies. Nevertheless, p38 and actin are clearly distinct from each other. We presume that p38 is a product of a maternal effect gene necessary for early dipteran development.

Amino Acid Sequence↗
PubMed1980

Cryptonephric malpighian tubule system in a dipteran larva, the New Zealand glow-worm, Arachnocampa luminosa (Diptera: Mycetophilidae): a structural study.

The Malpighian tubules of the glow-worm are divided into four morphologically distinct regions, each composed of a different cell type. Part 3 of the Malpighian tubules of A. luminosa is intimately bound to the rectum by a layer of fat body. This association of the tubules with the hindgut is referred to as a cryptonephric system. This type of arrangement has been described in some Coleoptera and the larvae of most Lepidoptera but has never before been reported in the Diptera. In the glow-worm the cryptonephric tubules themselves are small, and adjacent to the fat body the epithelial cells are modified to form very thin windows or 'leptophragmata' (Lison, 1937). The main epithelial cells exhibit features characteristic of highly active, secretory Malpighian tubule cells. The high density of mitochondria and their association with all the microvilli is indicative of a highly active secretory cell. The high concentration of glycogen in these cells and their intimate association with the hindgut suggest that they may, in addition, have a nutrient absorptive function. The role of the cryptonephric rectal complex in the glow-worm is discussed in the light of present knowledge gained from previous studies of coleopteran and larval lepidopteran cryptonephric systems. On structural grounds a model is proposed for the regulation of the ionic environment of the rectum, and the uptake and metabolism of organic material from the rectal lumen by this cryptonephric complex.

Animals↗
PubMed1996

Toxicological biotest on Diptera larvae to detect ciguatoxins and various other toxic substances.

A toxicological test was developed using a new animal sensitive to various toxins, especially ciguatoxin (CTX), which poisons humans who eat tropical fishes. The larvae of Parasarcophaga argyrostoma (Diptera, Sarcophagidae) were selected for their marked ability to consume spontaneously large quantities of various proteins; meat, fish flesh or liver, mussels, etc. Larvae grown on meat overnight can easily be observed without requiring optical instruments. Ten larvae were placed on 5 g of the sample to be tested, and left for 3-24 hr. Samples containing > 1 ng of CTX/g of flesh (moray.eel CTX) killed the larvae in about 3 hr; samples with lower concentrations inhibited larval growth, which can be noted with the marked eye. These readings were rendered objective by weighing the larvae before and after their being placed on the test sample and comparing the result to that of the control. The reading with the naked eye seems to be satisfactory up to 0.2 ng of CTX/g, while that by weighing was acceptable up to 0.10-0.15 ng/g. The coefficient of variation in the sensitive zone (approximately 50% of normal growth) was about 25% for a series of 11 experiments. P. argyrostoma larvae are sensitive to various other toxic substances, such as tetrodotoxin, okadaic acid, aflatoxin B1 and amanitin. The test is extremely simple in its theory and practice. It does not require complex materials or equipment and it is very inexpensive. It could be used to detect ciguatera toxins in the monitoring of fishing areas and for the commercialization of big-sized fish.

Animals↗
PubMed2006

Applying adult emergence as an endpoint in a post-exposure laboratory test using two midge species (Diptera: Chironomidae).

Several approaches have been used to evaluate biological impairment in aquatic ecosystems which can be categorized as either laboratory or field. In the recent years, the laboratory toxicity test approach has been extended to field exposures where ambient factors are allowed to influence the test response. Field exposures of laboratory test organisms require method modifications. In this paper, a novel in situ method is described which measures growth, survival and emergence of sediment inhabiting insects (Diptera: Chironomidae) that are used in standardized laboratory toxicity testing. Two standard chironomid species (Chironomus riparius and Chironomus tentans) were used to test the suitability of the approach and to compare the performance of the species. The larvae were transferred to the laboratory for emergence after 7 days in situ exposure which was compared to laboratory responses. Growth, survival and emergence were significantly lower in the in situ pre-exposure than in the laboratory. Also, emergence success was significantly lower in one reference sediment (LMR) than in the other test sediments in both in situ and the laboratory treatment. These lower response levels likely resulted from sediment characteristics and artifacts related to the exposure in the in situ chamber. Feeding and water quality within the exposure chamber appear to be factors that may differ markedly from the laboratory exposure and may affect organism responses. C. riparius developed (growth, emergence time) faster than C. tentans in all treatments, otherwise the species responded similarly. C. riparius may be a better alternative for the chronic in situ exposures because of shorter exposure times and reduced feeding requirements.

Analysis of Variance↗
PubMed2005

The early stages of three Palaearctic species of saproxylic hoverflies (Syrphidae, Diptera).

The third stage larva and puparium of the cerioidine hoverflies, Ceriana vespiformis (Latreille, 1804) and Sphiximorpha subsessilis (Illiger in Rossi, 1807) and the milesine, Spilomyia digitata (Rondani, 1865) (Diptera, Syrphidae) are described from specimens collected in the field. Ceriana vespiformis and S. digitata larvae were obtained from wet, decaying roots and tree holes of Fraxinus angustifolius L., respectively, in Spain and S. subsessilis from an exudation of sap on an Abies alba Miller tree in France.

Abies↗
PubMed2005

Regulation of Oestrus ovis (Diptera: Oestridae) populations in previously exposed and naïve sheep.

Larvae of Oestrus ovis (Insecta: Diptera: Oestridae) are common parasites of nasal and sinus cavities of sheep and goats. During larval development, a specific immune reaction is initiated by the host with a humoral local and systemic response and the recruitment of eosinophils and mast cells in the upper airways mucosae. Nevertheless, the roles of these responses in the regulation of O. ovis larvae populations in sheep are not yet known. The aim of this study was to compare the establishment and the development of larvae as well as some inflammatory or immune parameters between different groups of half-sibling sheep: (i) a primed group experimentally infected twice before a challenge infection, (ii and iii) two groups infected once only and previously treated with a long-lasting corticoïd before the challenge (one group) or not (the other group). A fourth group of non-infected animals was added in the experimental design. The larval establishment rate was 23% in the corticoïd treated group compared to about 10% in the two other infected groups. Moreover, the larval development appeared more rapid in the corticoïd treated group than in the two other infected groups suggesting that the inflammatory response is involved in the regulation of O. ovis populations. By contrast, no differences in the establishment rates were shown in the primed group compared to the naïve group (without corticoïd treatment) despite evidence of higher eosinophilia, serum specific IgG, and immediate hypersensibility to excretory-secretory products of larvae. The specific lymphocyte proliferation was reduced in the primed group compared to the naïve one suggesting that an immuno-suppression occurs following repetitive O. ovis infections.

Adrenal Cortex Hormones↗
PubMed2005

Species composition of Gasterophilus spp. (Diptera, Oestridae) causing equine gastric myiasis in southern Italy: parasite biodiversity and risks for extinction.

Horse gastrointestinal myiasis caused by larvae of Gasterophilus spp. (Diptera, Oestridae) flies has a worldwide distribution and, where present, it is primarily caused by larvae of Gasterophilus intestinalis and Gasterophilus nasalis. Other species, i.e., Gasterophilus inermis, Gasterophilus pecorum and Gasterophilus haemorrhoidalis, present in different or in the same regions of the gastrointestinal tract, were only occasionally reported in very limited areas of eastern European Countries and in central Italy. With the aim to contribute data on the species composition of Gasterophilus and on the seasonal variation of the infection pattern in southern Italy, 152 native horses were necropsied from January to December 2003 and Gasterophilus larvae were collected from the stomach, the small intestine and the rectum of each of them. On the whole, 125 (82.2%) horses were infected by larvae of Gasterophilus spp. and 214 second stage larvae (L2) and 13,342 third stage larvae (L3) collected. Five species of Gasterophilus were identified with the following prevalence: G. intestinalis=95.2%, G. nasalis=44.8%, G. inermis=15.2%, G. pecorum=2.6% and G. haemorrhoidalis=0.8%. L3 were retrieved throughout the observation period with the highest mean burdens from January to August 2003 while the lowest mean was registered from September to November 2003. L2 were collected in February-March 2003 and from September to December 2003. The majority of the animals (n=66, 43.4%) were infected with a single Gasterophilus species, however, 45 animals (29.6%) harboured 2 species, 12 animals (7.9%) 3 species and 2 animals (1.3%) 4 species. The trend of abundance in the L3 of G. intestinalis and G. nasalis, the most represented species, was highly concordant (r=0.5, p<0.001). A retrospective comparison of our results and of other data from four seasons of observation (1983-1986) in central Italy showed that the number of G. inermis, G. pecorum and G. haemorrhoidalis have been decreasing relative to G. intestinalis and G. nasalis which may suggest tendency toward the extinction of the three former species of Gasterophilus.

Age Factors↗
PubMed2006

Spook and Spookier code for stage-specific components of the ecdysone biosynthetic pathway in Diptera.

Ecdysteroids regulate many key developmental events in arthropods including molting and metamorphosis. Recently, members of the Drosophila Halloween group of genes, that are required for embryonic viability and cuticle deposition, have been shown to code for several cytochrome P450 enzymes that catalyze the terminal hydroxylation steps in the conversion of cholesterol to the molting hormone 20-hydroxyecdysone. These P450s are conserved in other insects and each is thought to function throughout development as the sole mediator of a particular biosynthetic step since, where analyzed, each is expressed at all stages of development and shows no closely related homolog in their respective genomes. In contrast, we show here that several dipteran genomes encode two novel, highly related, microsomal P450 enzymes, Cyp307A1 and Cyp307A2, that likely participate as stage-specific components of the ecdysone biosynthetic machinery. This hypothesis comes from the observation that Cyp307A1 is encoded by the Halloween gene spook (spo), but unlike other Halloween class genes, Dmspo is not expressed during the larval stages. In contrast, Cyp307a2, dubbed spookier (spok), is expressed primarily during larval stages within the prothoracic gland cells of the ring gland. RNAi mediated reduction in the expression of this heterochromatin localized gene leads to arrest at the first instar stage which can be rescued by feeding the larva 20E, E or ketodiol but not 7dC. In addition, spok expression is eliminated in larvae carrying mutations in molting defective (mld), a gene encoding a nuclear zinc finger protein that is required for production of ecdysone during Drosophila larval development. Intriguingly, mld is not present in the Bombyx mori genome, and we have identified only one spook homolog in both Bombyx and Manduca that is expressed in both embryos and larva. These studies suggest an evolutionary split between Diptera and Lepidoptera in how the ecdysone biosynthetic pathway is regulated during development.

Amino Acid Sequence↗
PubMed2004

Molecular phylogeny of the superfamily Tephritoidea (Insecta: Diptera): new evidence from the mitochondrial 12S, 16S, and COII genes.

The phylogeny of the superfamily Tephritoidea (Diptera: Muscomorpha) was reconstructed from three mitochondrial gene fragments (12S, 16S, and COII) using 49 species representing 19 tephritoid and related families. Phylogenetic signal present in different gene fragments as well as combinations of gene fragments was examined using the interior branch and bootstrap test values from minimum evolution method. The minimum evolution, maximum likelihood, and maximum parsimony trees based on a combined dataset of all three gene fragments provided insight concerning the following phylogenetic relationships: (1) two monophyletic groups (Group-1 and -2) within the superfamily Tephritoidea were clearly recognized; they are compatible with Willi Hennig's Pallopteroidea and Otitoidea that are not used in the contemporary higher classification; (2) the non-monophyletic nature of the family Platystomatidae; and (3) a sister group relationship of Conopidae to Tephritoidea was not supported; instead, our result suggested that Conopidae and Diopsidae might be the basal most groups among the schizophoran families included in this study. The combined data of 12S, 16S, and COII genes was found, therefore, to be a viable genetic marker to resolve divergences among families of the Tephritoidea and other related superfamilies.

Animals↗