EVOLUTION, Issue 1 2009
Anton Pauw
The idea of coevolution originated with Darwin's proposal that long-proboscid pollinators and long-tubed flowers might be engaged in reciprocal selection, but this has not been demonstrated. Here we test key aspects of Darwin's hypothesis of reciprocal selection in an experiment with naturally interacting populations of extremely long-proboscid flies (Moegistorhynchus longirostris: Nemestinidae) and long-tubed irises (Lapeirousia anceps: Iridaceae). We show that the benefit derived by both the fly (volume of nectar consumed) and the plant (number pollen grains received) depends on the relative length of their interacting organs. Each trait is shown to act both as agent and target in directional reciprocal selection, potentially leading to a race. This understanding of how fitness in both species varies in relation to the balance of their armament allows us to make tentative predictions about the nature of selection across multiple communities. We find that in each community a core group of long-tubed plant species might together be involved in diffuse coevolution with the fly. In poorly matched populations, the imbalance in armament is too great to allow reciprocal selection to act, and these species might instead experience one-sided selection that leads to convergence with the core species. Reciprocal selection drives the evolution of the community, then, additional species become attached to the network of interacting mutualists by convergence. [source]

ENTRY-LEVEL POLICE CANDIDATE ASSESSMENT CENTER: AN EFFICIENT TOOL OR A HAMMER TO KILL A FLY?

PERSONNEL PSYCHOLOGY, Issue 4 2002
KOBI DAYAN
The study examined the validity of the assessment center (AC) as a selection process for entry-level candidates to die police and its unique value beyond cognitive ability tests. The sample included 712 participants who responded to personality and cognitive ability testing (CAT), and underwent an AC procedure. AC results included the overall assessment rating (OAR) and peer evaluation (PE). Seven criterion measures were collected for 585 participants from a training stage and on-the-job performance. Results showed that the selection system was valid. Findings yielded significant unique validities of OAR and PE beyond CAT and of PE beyond OAR even after corrections for restriction of range. Results support the use of ACs for entry-level candidates. [source]

Flies and concealed nectar sources: morphological innovations in the proboscis of Bombyliidae (Diptera)

ACTA ZOOLOGICA, Issue 3 2002
N. U. Szucsich
Abstract Bee-flies (Bombyliidae) have morphological adaptations of the mouthparts to particular floral traits. To investigate this the short, plesiomorphic proboscis of Hemipenthes morio was compared with the long, apomorphic proboscis of Bombylius major. A novel feeding position enables B. major to use flowers that open to the side as additional nectar sources. The new horizontal feeding position is enabled by the prolonged ventral base of the proboscis. Bombylius major exploits deep corolla tubes with an elongate proboscis, and an increased efficiency in both the suction pumps and the sealing mechanisms of the proboscis. The exploitation of narrow corolla tubes is made possible by the shift from a sponging feeding mode, exhibited by H. morio, to the exclusively sucking mode in B. major. Besides quantitative changes in the proportions of the different proboscis components, labellar movements as well as the structures of saliva distribution are changed along with this shift. The labial musculature of B. major does not significantly differ from the plesiomorphic state, since both examined species do not only feed on nectar, but also on pollen. [source]

Temperature-dependent ovariole and testis maturation in the yellow dung fly

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2005
Wolf U. Blanckenhorn
Abstract Temperature is one of the abiotic environmental factors most strongly affecting animal behaviour, physiology, and life history. In insects, lower temperatures generally slow down most physiological processes, reducing growth rate and prolonging the juvenile period. Here, we investigate temperature-dependent ovariole and testis maturation in the anautogenous yellow dung fly, Scathophaga stercoraria L. (Diptera: Scathophagidae), and relate it to corresponding temperature effects on pre-adult development time and the adult pre-reproductive period. Flies were reared in the laboratory at three constant temperatures (18, 22, and 26 °C), and the size of the developing ovarioles and testes (reflecting sperm production) was measured over time (i.e., age). Ovariole size increased asymptotically over the first 12 days of adult life, while the testes continued to fill after day 10. In accordance with the temperature-size rule, warmer temperatures resulted in smaller ovarioles (eggs) and smaller testes, independent of body size. Warmer temperatures also greatly reduced pre-adult development time by more than half, from 12 to 25 °C, the larger males always taking 1,3 days longer than the females. Corresponding temperature effects on the adult pre-reproductive period were small (<1 day between 15 and 25 °C), with males taking 5,6 days and females 10,13 days to first reproduction. Time lost by males during the pre-adult stage, when ovaries and testes are produced, can thus be more than compensated-for by time gained during the pre-reproductive period, when eggs and sperm are produced, so males can nevertheless start reproducing sooner than females. [source]

Management of Fruit Flies (Diptera: Tephritidae) of the Most Perishable Fruits

ENTOMOLOGICAL RESEARCH, Issue 2 2005
Muhammad Ahsan KHAN
ABSTRACT We investigated to minimize the dependency on the use of chemicals and thus develop safe and environmental friendly control program for the most perishable fruits i.e., apple,,ber', guava and mango. Our findings on the composition of fruit fly species reveal that Bactrocera dorsalis was dominant on apple (33.96% existence), Corpomya incompleta on,ber'(51.91% existence) and Bactrocera zonata on guava (49.62% existence) and mango (74.66% existence). The correlation between population and infestation percentage was non-significant in apple orchards, whereas positive and highly significant in between population and infestation, as well as on the cumulative basis in,ber', guava and mango orchards during 1998-1999. Hoeing, baiting and methyl eugenol were statistically equal resulting about 77% decrease in infestation. The maximum control of 91.68% was observed where all four-control operations including Dipterex® were integrated together. Weather factors, when computed together, had maximum effect on population fluctuation and infestation with rainfall contributing the major role. For guava fruits, the months of August (14.06A individuals/trap/day) and September (13.81A individuals/trap/day) were important, resulting in maximum infestation percentage of 10.76 to 14.74%, respectively. [source]

Thermogenesis and respiration of inflorescences of the dead horse arum Helicodiceros muscivorus, a pseudo-thermoregulatory aroid associated with fly pollination

FUNCTIONAL ECOLOGY, Issue 6 2003
R. S. Seymour
Summary 1In central Corsica, Helicodiceros muscivorus (Schott ex. K. Koch) produces a protogynous inflorescence that resembles the anal area of a dead mammal and produces a foetid scent during the few hours after sunrise. Flies enter the floral chamber, pollinate the female florets and become trapped until the next morning, when pollen is shed from the male florets and the flies are released. 2The exposed appendix exhibits a strong, unimodal episode of thermogenesis associated with scent production, reaching a maximum of 30 °C at 15 °C ambient temperature. The male florets in the floral chamber are highly thermogenic throughout the second night and generally maintain stable floret temperatures of about 24 °C at ambient temperatures down to 13 °C. 3Maximum respiration rates of the appendix (0·45 µmol CO2 s,1 g,1) and the male florets (0·82 µmol s,1 g,1) may be the highest recorded for plant tissue. 4Thermogenesis of the appendix does not depend on ambient temperature, but that of the male florets increases with decreasing ambient temperature in most cases. However, the pattern of heat production by the males appears related more to time than to ambient temperature, hence the term ,pseudo-thermoregulation'. 5The behaviour and thoracic temperatures of flies emerging from captivity suggests that male floral warming does not enhance their activity. [source]

Genetic variation in thermal tolerance among natural populations of Drosophila buzzatii: down regulation of Hsp70 expression and variation in heat stress resistance traits

FUNCTIONAL ECOLOGY, Issue 3 2001
J. G. Sørensen
Summary 1,Thermal adaptation was investigated in the fruitfly Drosophila buzzatii Patterson and Wheeler. Two natural populations originating from a high- and a low-temperature environment, respectively, were compared with respect to Hsp70 (heat shock protein) expression, knock-down resistance and heat shock resistance. 2,Three main hypotheses were tested: (i) The expression level of Hsp70 in flies from the high-temperature habitat should be down-regulated relative to flies from the colder habitat. (ii) Flies having higher Hsp70 expression levels should be weakened most by a hardening treatment and go faster into coma, as Hsp70 level reflects stress intensity, and therefore display reduced heat knock-down resistance. (iii) Heat shock resistance should be increased in the population with highest Hsp70 expression because the level of Hsp70 is positively associated with this trait. 3,The results generally matched the hypotheses. Hsp70 expression was reduced in the high-temperature population. Knock-down resistance was higher in the high-temperature population and survival after heat shock was lower in the high-temperature population. 4,This study showed genetic differences in thermal tolerance between populations, indicating that high temperature in nature may be an important selective factor. Moreover, knock-down resistance in this study seems to be a more relevant trait than standard heat shock resistance for identifying thermal adaptation in natural populations. [source]

Feeding history effects on feeding responses of Rhagoletis indifferens (Dipt., Tephritidae) to GF-120 and Nulure

JOURNAL OF APPLIED ENTOMOLOGY, Issue 9-10 2006
W. L. Yee
Abstract:, Effects of feeding history on feeding responses of western cherry fruit fly, Rhagoletis indifferens Curran, to the commercial protein baits GF-120 and Nulure were determined in the laboratory. Flies were kept on 5% sucrose alone or yeast extract and sucrose (Y + S) for 3,7 or 14,16 days and exposed to 24-h-old GF-120 or Nulure drops on artificial leaves. Numbers and durations of feeding events on leaves and durations of non-feeding events were recorded over 1-h periods. Experiments were also conducted to determine effects of Y + S feeding sequences on responses to Nulure, of starvation after sucrose or Y + S feeding on responses to Nulure, and of feeding history on mortality after exposure to GF-120 and Nulure. Protein-deprived flies consistently fed more times on GF-120 and Nulure than protein-fed flies and fed longer. One day of exposure to Y + S or 16 h of starvation after exposure to sucrose caused greater feeding on Nulure than 7 days of exposure to Y + S or 16 h of starvation after exposure to Y + S. Durations of non-feeding events on leaves with sucrose or bait were similar in protein-deprived and -fed flies. Responses of 4- to 6-day-old flies kept on sucrose to 0- and 24-h-old GF-120 or Nulure were similar. More flies kept on sucrose were paralysed or dead at 6,32 h after exposure to GF-120 or Nulure with spinosad than flies kept on Y + S. Results show that complete or long periods of protein deprivation and starvation after sucrose feeding increased feeding responses to GF-120 and Nulure. The general lack of differences in durations of non-feeding events on leaves with sucrose or GF-120 or Nulure in protein-deprived and -fed flies suggests that most protein-deprived flies found baits through chance encounters following normal movement. [source]

The Nocturnal Ovipositing Behavior of Carrion Flies in Cincinnati, Ohio

JOURNAL OF FORENSIC SCIENCES, Issue 6 2009
Trevor Stamper Ph.D.
Abstract:, The behavioral patterns of nocturnal oviposition represent a window of time that potentially has a large impact on postmortem interval estimations. We investigated the behavioral patterns of carrion flies at night by exposing euthanized rats between sunset and sunrise to see if carrion flies oviposited upon the carrion over two consecutive summers. We investigated urban and rural locations, in both lit and unlit conditions with n = 125. We found that nocturnal ovipositing did not occur in the Cincinnati metropolitan area. We conclude that nocturnal oviposition is an unlikely event in the Cincinnati metropolitan area. [source]

Ethanol-Regulated Genes That Contribute to Ethanol Sensitivity and Rapid Tolerance in Drosophila

ALCOHOLISM, Issue 2 2010
Eric C. Kong
Background:, Increased ethanol intake, a major predictor for the development of alcohol use disorders, is facilitated by the development of tolerance to both the aversive and pleasurable effects of the drug. The molecular mechanisms underlying ethanol tolerance development are complex and are not yet well understood. Methods:, To identify genetic mechanisms that contribute to ethanol tolerance, we examined the time course of gene expression changes elicited by a single sedating dose of ethanol in Drosophila, and completed a behavioral survey of strains harboring mutations in ethanol-regulated genes. Results:, Enrichment for genes in metabolism, nucleic acid binding, olfaction, regulation of signal transduction, and stress suggests that these biological processes are coordinately affected by ethanol exposure. We also detected a coordinate up-regulation of genes in the Toll and Imd innate immunity signal transduction pathways. A multi-study comparison revealed a small set of genes showing similar regulation, including increased expression of 3 genes for serine biosynthesis. A survey of Drosophila strains harboring mutations in ethanol-regulated genes for ethanol sensitivity and tolerance phenotypes revealed roles for serine biosynthesis, olfaction, transcriptional regulation, immunity, and metabolism. Flies harboring deletions of the genes encoding the olfactory co-receptor Or83b or the sirtuin Sir2 showed marked changes in the development of ethanol tolerance. Conclusions:, Our findings implicate novel roles for these genes in regulating ethanol behavioral responses. [source]

An Assay for Evoked Locomotor Behavior in Drosophila Reveals a Role for Integrins in Ethanol Sensitivity and Rapid Ethanol Tolerance

ALCOHOLISM, Issue 10 2009
Poonam Bhandari
Background:, Ethanol induces similar behavioral responses in mammals and the fruit fly, Drosophila melanogaster. By coupling assays for ethanol-related behavior to the genetic tools available in flies, a number of genes have been identified that influence physiological responses to ethanol. To enhance the utility of the Drosophila model for investigating genes involved in ethanol-related behavior, we explored the value of an assay that measures the sedative effects of ethanol on negative geotaxis, an evoked locomotor response. Methods:, We established eRING (ethanol Rapid Iterative Negative Geotaxis) as an assay for quantitating the sedative effects of ethanol on negative geotaxis (i.e., startle-induced climbing). We validated the assay by assessing acute sensitivity to ethanol and rapid ethanol tolerance in several different control strains and in flies with mutations known to disrupt these behaviors. We also used eRING in a candidate screen to identify mutants with altered ethanol-related behaviors. Results:, Negative geotaxis measured in eRING assays was dose-dependently impaired by ethanol exposure. Flies developed tolerance to the intoxicating effects of ethanol when tested during a second exposure. Ethanol sensitivity and rapid ethanol tolerance varied across 4 control strains, but internal ethanol concentrations were indistinguishable in the 4 strains during a first and second challenge with ethanol. Ethanol sensitivity and rapid ethanol tolerance, respectively, were altered in flies with mutations in amnesiac and hangover, genes known to influence these traits. Additionally, mutations in the , integrin gene myospheroid and the , integrin gene scab increased the initial sensitivity to ethanol and enhanced the development of rapid ethanol tolerance without altering internal ethanol concentrations. Conclusions:, The eRING assay is suitable for investigating genetic mechanisms that influence ethanol sensitivity and rapid ethanol tolerance. Ethanol sensitivity and rapid ethanol tolerance depend on the function of , and , integrins in flies. [source]

Flies in the ointment: a morphological and molecular comparison of Lucilia cuprina and Lucilia sericata (Diptera: Calliphoridae) in South Africa

MEDICAL AND VETERINARY ENTOMOLOGY, Issue 1 2009
R. TOURLE
Abstract Complementary nuclear (28S rRNA) and mitochondrial (COI) genes were sequenced from blowflies that phenotypically resembled Lucilia cuprina (W.), Lucilia sericata (Meigen) or exhibited characters of both species. The aim was to test a long-held hypothesis that these species hybridize under natural conditions in South Africa (Ullyett, 1945). Blowflies were obtained predominantly from the Cape Town metropolitan area, but reference samples were acquired for L. sericata from Pretoria. Several L. cuprina -like flies were shown to possess a conflicting combination of nuclear and mitochondrial genes that has also been seen in Hawaiian specimens. Homoplasy, sampling of pseudogenes, hybridization and incomplete lineage sorting are discussed as possible hypotheses for the pattern and the latter is concluded to represent the most likely explanation. [source]

Identification of the intermediate hosts of Habronema microstoma and Habronema muscae under field conditions

MEDICAL AND VETERINARY ENTOMOLOGY, Issue 3 2008
D. TRAVERSA
Abstract A polymerase chain reaction (PCR)-based assay was used for the specific detection of Habronema microstoma and Habronema muscae (Nematoda, Spirurida) in order to identify the intermediate hosts of both nematode species under field conditions. A total of 1087 netted and 165 laboratory-bred flies were tested. Flies were identified as Musca domestica Linnaeus 1758, Musca autumnalis De Geer 1776, Haematobia irritans (Linnaeus 1758), Haematobia titillans (De Geer 1907) and Stomoxys calcitrans (Linnaeus 1758) (Muscidae). Genomic DNA was extracted from pools of fly heads, thoraces and abdomens, and 703 samples were subjected to a duplex two-step semi-nested PCR assay to specifically detect diagnostic regions within the ribosomal ITS2 sequence of both H. microstoma and H. muscae. Stomoxys calcitrans specimens were positive for H. microstoma DNA and M. domestica specimens were positive for H. muscae DNA. In particular, PCR-positive samples derived from both farm-netted and laboratory-bred flies. The present study represents the first evidence of the vectorial competence of different fly species as intermediate hosts of Habronema stomachworms under field conditions. We discuss the roles of S. calcitrans and M. domestica in transmitting H. microstoma and H. muscae. [source]

Is there safety in numbers?

MEDICAL AND VETERINARY ENTOMOLOGY, Issue 4 2007
The effect of cattle herding on biting risk from tsetse flies
Abstract In sub-Saharan Africa, tsetse (Glossina spp.) transmit species of Trypanosoma which threaten 45,50 million cattle with trypanosomiasis. These livestock are subject to various herding practices which may affect biting rates on individual cattle and hence the probability of infection. In Zimbabwe, studies were made of the effect of herd size and composition on individual biting rates by capturing tsetse as they approached and departed from groups of one to 12 cattle. Flies were captured using a ring of electrocuting nets and bloodmeals were analysed using DNA markers to identify which individual cattle were bitten. Increasing the size of a herd from one to 12 adults increased the mean number of tsetse visiting the herd four-fold and the mean feeding probability from 54% to 71%; the increased probability with larger herds was probably a result of fewer flies per host, which, in turn, reduced the hosts' defensive behaviour. For adults and juveniles in groups of four to eight cattle, > 89% of bloodmeals were from the adults, even when these comprised just 13% of the herd. For groups comprising two oxen, four cows/heifers and two calves, a grouping that reflects the typical composition of communal herds in Zimbabwe, , 80% of bloodmeals were from the oxen. Simple models of entomological inoculation rates suggest that cattle herding practices may reduce individual trypanosomiasis risk by up to 90%. These results have several epidemiological and practical implications. First, the gregarious nature of hosts needs to be considered in estimating entomological inoculation rates. Secondly, heterogeneities in biting rates on different cattle may help to explain why disease prevalence is frequently lower in younger/smaller cattle. Thirdly, the cost and effectiveness of tsetse control using insecticide-treated cattle may be improved by treating older/larger hosts within a herd. In general, the patterns observed with tsetse appear to apply to other genera of cattle-feeding Diptera (Stomoxys, Anopheles, Tabanidae) and thus may be important for the development of strategies for controlling other diseases affecting livestock. [source]

Lifespan and patterns of accumulation and mobilization of nutrients in the sugar-fed phorid fly, Pseudacteon tricuspis

PHYSIOLOGICAL ENTOMOLOGY, Issue 3 2005
Henry Y. Fadamiro
Abstract., The effect of sugar feeding on the survival of adult phorid fly Pseudacteon tricuspis is investigated. Flies fed 25% sucrose in aqueous solution continuously throughout their lifespan have greater longevity (mean ± SE longevity: female = 7.9 ± 0.8 days, male = 8.9 ± 0.9 days) than completely starved (provided no water and no sugar solution) flies, sugar-starved (provided water only) flies, or flies fed sugar solution only on their first day of adult life. Completely starved flies rarely lived beyond one day. Provision of water increases longevity by 2 days, and one full day of sugar feeding further increases longevity by an additional 1,2 days. Flies fed 50% sucrose have similar survivorship as those fed 25% sucrose. The temporal patterns of nutrient accumulation and utilization are also compared in P. tricuspis fed different diets: sugar-starved, sucrose-fed on the first day of adult life only, and sucrose-fed continuously. Adult P. tricuspis emerge with no gut sugars, and only minimal amounts of body sugars and glycogen. Although the levels of body sugars and glycogen decline gradually in sugar-starved flies, a single day of sugar feeding results in the accumulation of maximum amounts of gut sugars, body sugars and glycogen. High levels of these nutrients are maintained in female and male phorid flies fed on sucrose continuously over the observation period, whereas nutrient levels decline in flies fed only on the first day of life, beginning 1 day postfeeding. Female and male P. tricuspis emerge with an estimated 12.3 ± 2.3 and 7.2 ± 1 g of lipid reserves per fly, respectively. These teneral amounts represent the highest lipid levels detected in adult flies, irrespective of their diet, and are maintained over the life times of sucrose-fed female and male flies, but declined steadily in sugar-starved females. These data suggest that adult P. tricuspis are capable of converting dietary sucrose to body sugars and glycogen, but not lipids. [source]

Molecular Characterization of Gregarines from Sand Flies (Diptera: Psychodidae) and Description of Psychodiella n. g. (Apicomplexa: Gregarinida)

THE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 6 2009
JAN VOTÝPKA
ABSTRACT. Sand fly and mosquito gregarines have been lumped for a long time in the single genus Ascogregarina and on the basis of their morphological characters and the lack of merogony been placed into the eugregarine family Lecudinidae. Phylogenetic analyses performed in this study clearly demonstrated paraphyly of the current genus Ascogregarina and revealed disparate phylogenetic positions of gregarines parasitizing mosquitoes and gregarines retrieved from sand flies. Therefore, we reclassified the genus Ascogregarina and created a new genus Psychodiella to accommodate gregarines from sand flies. The genus Psychodiella is distinguished from all other related gregarine genera by the characteristic localization of oocysts in accessory glands of female hosts, distinctive nucleotide sequences of the small subunit rDNA, and host specificity to flies belonging to the subfamily Phlebotominae. The genus comprises three described species: the type species for the new genus,Psychodiella chagasi (Adler and Mayrink 1961) n. comb., Psychodiella mackiei (Shortt and Swaminath 1927) n. comb., and Psychodiella saraviae (Ostrovska, Warburg, and Montoya-Lerma 1990) n. comb. Its creation is additionally supported by sequencing data from other gregarine species originating from the sand fly Phlebotomus sergenti. In the evolutionary context, both genera of gregarines from mosquitoes (Ascogregarina) and sand flies (Psychodiella) have a close relationship to neogregarines; the genera represent clades distinct from the other previously sequenced gregarines. [source]

Effects of 20-hydroxyecdysone and juvenile hormone on octopamine metabolism in females of Drosophila

ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 4 2009
E. V. Bogomolova
Abstract The effect of exogenous 20-hydroxyecdysone (20E) and juvenile hormone (JH) on the activities of the tyrosine decarboxylase (TDC), the first enzyme in octopamine (OA) synthesis, has been studied in young females of wild type D. virilis and D. melanogaster under normal and heat stress (38°C) conditions. Flies fed 20E expressed increased TDC activity in both species. JH application decreased TDC activity in both species. A rise in JH and 20E levels did not prevent a TDC response to heat stress, but changed the response intensity. A long-term increase in JH titre had no effect on the activity of main OA catabolyzing enzyme, arylalkylamine N-acetyltransferase, in females of both species. A possible mechanism of regulation of OA levels by 20E and JH in Drosophila females is discussed. © 2009 Wiley Periodicals, Inc. [source]

Courtship dances in the flies of the genus lispe (Diptera: Muscidae): From the fly's viewpoint

ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 1 2006
Leonid Frantsevich
Abstract Two predatory fly species, Lispe consanguinea Loew, 1858 and L. tentaculata DeGeer, 1776, inhabit the supralittoral zone at the shore of a fresh-water reservoir. Both species look alike and possess similar "badges," reflective concave silvery scales on the face. Flies occupy different lek habitats. Males of the first species patrol the bare wet sand on the beach just above the surf. Males of the second species reside on the more textured heaps of algae and stones. Courtship and aggressive behaviour of males was video-recorded and analysed frame by frame. Visual stimuli provided by the conspecific partner were computed in the body-fixed space of a fly observer. Males of L. consanguinea perform long pedestrian dances of pendulating circular arcs (frequency 2 s,1, median radius 2.5 cm, linear velocity 0.130 m/s). Right and left side runs are equally probable. Circular runs are interrupted by standby intervals of average duration 0.35 s. The female views the male as a target covering 2 by 2 ommatidia, moving abruptly with the angular velocity over 200 °/s in a horizontal direction down the path of about 50° till the next standpoint. Dancing is evenly distributed around the female. On the contrary, the male fixates the image of the female within the narrow front sector (median ±10°); the target in his view has 6,7 times less angular velocity and angular span of oscillations, and its image in profile overlays 6,8 by 2 ommatidia. If the female walks, the male combines tracking with voluntary circular dances. Rival males circle about one another at a distance shorter than 15 mm, but not in close contact. Males of L. tentaculata are capable of similar circular courting dances, but do so rarely. Usually they try to mount any partner immediately. In the latter species, male combat consists of fierce wrestling. Flies of both species often walk sideward and observe the partner not in front but at the side. Arch. Insect Biochem. Physiol. 62:26,42, 2006. © 2006 Wiley-Liss, Inc. [source]

Size-Dependent Mating Success at Various Nutritional States in the Yellow Dung Fly

ETHOLOGY, Issue 8 2008
Wolf U. Blanckenhorn
Mating success not only depends on genetic quality, but also equally on environmental factors, most prominently food availability. We investigated the interactive effects of nutritional state and body size on mating success and copula duration in yellow dung fly males (Scathophaga stercoraria; Diptera: Scathophagidae) of three body size selection lines in the laboratory in both non-competitive (single) and competitive (group) situations. Adults require protein and lipids from prey to reproduce, as well as sugars as an energy source for reproductive activity. We expected mating success to decrease with time because of sperm depletion (sugar treatment) and/or energy shortage (water treatment) relative to the control, prey plus sugar treatment. Based on physiological scaling, we also expected large-line males to become depleted either sooner because of their higher energy and sperm demands, or later because of their more efficient energy use. Average mating success indeed declined over a period of 5,7 d (or 5,15 potential copulations per male), but equally for all food treatments and body size classes. Surprisingly, water-fed and small-line males had the highest mating probability in the non-competitive setting, while in the competitive setting large-line males had the highest success. Energy-depleted males showed apparent terminal investment. Small males acquired females more readily but eventually lost them to larger males in the competitive situation. As shown before, copula duration was inversely related to body size and increased with copulation number, independent of food treatment. We conclude that sugar or prey shortage has little effect on mating success in the short term, and does not differentially affect males of different sizes. [source]

In the Cockpit of the Fly

GERMAN RESEARCH, Issue 1 2003
Martin Egelhaaf Prof. Dr.
Small brains can completely outclass large ones in their performance. Thus the fly has proved to be an outstanding model system for image processing in the brain [source]

Waiter, There's a Fly in My Soup!

HYPATIA, Issue 3 2004
Reflections on the Philosophical Gourmet Report
Editor's note: with this essay, Hypatia inaugurates a new column. We welcome musings on the state of the profession, the life of the independent scholar, political activism, teaching, publishing, or other topics of interest to feminist philosophers. We particularly invite submissions that pick up conversational threads begun by earlier contributions to the column, so that Musings becomes a forum for talking to one another. If you have an idea for the column, please tell us about it. [source]

Fly or die: the role of fat stores in the growth and development of Grey-headed Albatross Diomedea chrysostoma chicks

IBIS, Issue 2 2000
KEITH REID
Chicks of albatrosses, like other Procellariiformes, become independent at a mass similar to their parents but during growth attain a peak mass some 30% or more greater, before losing mass prior to fledging. The current views are that this high peak mass represents chicks storing fat reserves as an energy sink, or as an insurance against periodic food scarcity, or as a Consequence of natural stochastic variation in provisioning rate. We analysed growth and body composition of Grey-headed Albatross Diomedea chrysostoma chicks at Bird Island, South Georgia in 1984 and 1986, two years of very different food availability. In 1984 when overall breeding success was only 28% (the lowest in 20 years and less than halt that in 1986), chicks were significantly smaller in terms of peak mass (by 37%), primary length (by 25%), liver, lung, heart and kidney size (by 18,34%) and fat (by 75,80%) but not significantly different in terms of skeletal (tarsus, culmen, ulna, sternum) or muscle (pectoral, leg) size. Despite these differences, there were some important similarities in the patterns of growth in both years. Up to the attainment of peak mass, most of the growth of organs and of skeletal structures was completed and little fat was deposited. In the remaining part of the chick-rearing period, feather growth and acquisition of fat stores were undertaken. Thus Grey-headed Albatross chicks begin to acquire substantial fat stores only during the later part of the development period; this is contrary to the predictions of any of the existing hypotheses concerning provisioning patterns and the role of fat stores in Procellariiformes. We propose that the deposition of fat in the later stages of chick growth is an adaptation to: (a) ensure against energy demands and/or nutritional stress affecting the quality of flight feathers (many of which are not renewed for up to three years after fledging); and (b) provide an energy reserve for chicks to use in the critical period immediately after independence. [source]

Perceived Risk and Worry: The Effects of 9/11 on Willingness to Fly,

JOURNAL OF APPLIED SOCIAL PSYCHOLOGY, Issue 9 2004
Rochelle L. Bergstrom
Most decision-making models rely on affect-free variables to understand the decisions that people make. We tested an affectively-loaded variable,worry,as a predictor of decision making in an affectively laden context: willingness to fly after 9/11. College students rated their willingness to fly to New York City or Washington, DC, in a study conducted 34 days after 9/11. They also recorded their beliefs about the likelihood that more terrorist attacks would occur, the severity of such attacks if they were to occur, and how much they worried about flying. Finally, they made these estimates for similar others. Results showed that worry was the most powerful predictor of one's own and similar others' willingness to fly. These findings suggest that models of how people make decisions may sometimes need to take feelings into account. [source]

Fly through galaxies in planetarium

ASTRONOMY & GEOPHYSICS, Issue 1 2009
Article first published online: 16 JAN 200
No abstract is available for this article. [source]

Fighting and Flying: Archival Analysis of Threat, Authoritarianism, and the North American Comic Book

POLITICAL PSYCHOLOGY, Issue 6 2005
Bill E. Peterson
In this archival study, themes of authoritarianism (Adorno, Frenkel-Brunswik, Levinson, & Sanford, 1950) were content coded in American comic books. Comic books produced during years of relatively high social and economic threat (1978,82 and 1991,92) contained more aggressive imagery, more conventional themes, less intraception, and fewer spoken lines by women characters relative to comic books produced during years of relatively low threat (1983,90). Unexpectedly, speaking roles for characters of color did not differ due to the influence of threat. Discussion focused on the theoretical relationship between threat and manifestations of authoritarianism at the societal and individual levels. [source]

Stress Resistance and Environmental Dependency of Inbreeding Depression in Drosophila melanogaster

CONSERVATION BIOLOGY, Issue 4 2000
Jesper Dahlgaard
Two important issues are whether stress and inbreeding effects are independent as opposed to synergistic, and whether inbreeding effects are general across stresses as opposed to stress-specific. We found that inbreeding reduced resistance to acetone and desiccation in adult Drosophila melanogaster, whereas resistance to knockdown heat stress was not affected. Inbred flies, however, experienced a greater proportional decrease in productivity than outbreds following heat stress. Correlations using line means indicated that all resistance traits were uncorrelated in the inbred as well as in the outbred flies. Recessive, deleterious alleles therefore did not appear to have any general deleterious effects on stress resistance. Inbreeding within a specific environment and selection for resistant genotypes may therefore purge a population of deleterious genes specific to only one environmental stress. Resumen: Tanto la endogamia como el estrés ambiental pueden tener efectos adversos sobre la adaptabilidad afectando la conservación de especies en peligro de extinción. Dos temas importantes son determinar si los efectos del estrés y la endogamia son independientes en lugar de ser sinérgicos, y determinar si los efectos de la endogamia son generales para distintos tipos de estrés o si son específicos para un tipo determinado de estrés. Encontramos que la endogamia reduce la resistencia a la acetona y la desecación en adultos de Drosophila melanogaster, mientras que la resistencia al efecto demoledor del estrés por calor no fue afectada. Sin embargo, las moscas endogámicas experimentaron una disminución proporcionalmente mayor en la productividad que aquellas moscas sin endogamia después de experimentar un estrés por calor. Las correlaciones obtenidas usando líneas medias indicaron que las características de resistencia no estuvieron correlacionadas ni en moscas con endogamia, ni en moscas sin ella. Aparentemente los alelos nocivos recesivos no tuvieron ningún efecto nocivo general en la resistencia al estrés. La endogamia dentro de un ambiente específico y la selección por genotipos resistentes podrían, por lo tanto, eliminar una población de genes nocivos específicos a un solo estrés ambiental. [source]

Relapse prevention with sex offenders: practice, theory and research

CRIMINAL BEHAVIOUR AND MENTAL HEALTH, Issue 1 2001
Gilles Launay Head of Psychology
Introduction Relapse prevention (RP) is now applied to sex offending. It has been questioned as to whether RP is worthwhile. This paper aims to evaluate this technique. The Rochester RP programme The purpose of the Rochester RP programme is to refine and strengthen skills gained in the prison department's sex offender treatment programme. The objective of the programme is to teach prisoners to recognize the chain of events leading up to their current offences and to practise strategies to interrupt this chain. Theoretical basis for RP Stopping an undesired behaviour and maintaining abstinence are two different problems. RP aims to address the maintenance problems. At the centre of RP theory is a study of the conditions that can turn lapse into relapse. Yet RP has been criticized as a lot of jargon saying very little. Ward and Hudson criticize RP constructs and their interaction. Such debates have few implications for clinical work and most of the criticism flies in the face of clinical experience. Research basis for RP Risk factors for sex offenders are being identified. Local evaluation of the Rochester programme suggests that prisoners do learn to identify risk factors and to develop coping strategies. As yet, however, there is no evidence as to whether RP works or not. Discussion A way to improve the efficacy of an RP programme may be to augment it with additional modules, e.g. behaviour therapy, drug treatment, continued work with the same prison staff and relaxation training. Conclusion RP theory is sound in essence but suffers from an overlay of cumbersome vocabulary. Reliable research is emerging. Copyright © 2001 Whurr Publishers Ltd. [source]

Words, flies, Jews, Joyce, Joint: Wyndham Lewis and the unpublishing of obscenity

CRITICAL QUARTERLY, Issue 4 2004
Geoff Gilbert
First page of article [source]

The Drosophila nucleoporin gene nup154 is required for correct microfilament dynamics and cell death during oogenesis

CYTOSKELETON, Issue 8 2007
Maria Giovanna Riparbelli
Abstract The Drosophila nucleoporin gene nup154 is required in both male and female germline for successful gametogenesis. Mutant flies lack differentiated sperm and lay abnormal eggs. We demonstrated that the egg phenotype was associated with specific alterations of the actin cytoskeleton at different stages of oogenesis. Actually, mutant egg chambers displayed an abnormal organization of both subcortical microfilaments and cytoplasmic actin bundles, that led to defective nurse cell dumping. TUNEL analysis also showed that the dumpless phenotype was associated with delayed apoptosis. The nup154 gene product was localized by conventional immunofluorescence microscopy to the nuclear envelope in a distinct punctuate pattern, characteristic of nuclear pore complex components. TEM analysis revealed that the protein was mainly distributed along filamentous structures that extended radially on the nuclear side of the pore, suggesting that Nup154 could be an integral component of the basket filaments associated with the nuclear pore complexes. We propose that Nup154 is necessary for correct nuclear pore complex functions and that the proper regulation of the actin cytoskeleton dynamics strongly relies upon nuclear pore integrity. Cell Motil. Cytoskeleton 2007. © 2007 Wiley-Liss, Inc. [source]

Morphological irregularities and features of resistance to apoptosis in the dcp-1/pita double mutated egg chambers during Drosophila oogenesis

CYTOSKELETON, Issue 1 2005
Ioannis P. Nezis
Abstract In the present study, we demonstrate the most novel characteristic morphological features of Drosophila egg chambers lacking both dcp-1 and pita functions in the germline cells. Dcp-1 is an effector caspase and it has been previously shown to play an important role during Drosophila oogenesis [McCall and Steller, 1998 : Science 279 : 230,234; Laundrie et al., 2003 : Genetics 165 : 1881,1888; Peterson et al., 2003 : Dev Biol 260 : 113,123]. The completion of sequencing and annotation of the Drosophila genome has revealed that the dcp-1 gene is nested within an intron of another distinct gene, called pita, a member of the C2H2 zinc finger protein family that regulates transcriptional initiation. The dcp-1,/,/pita,/, nurse cells exhibit euchromatic nuclei (delay of apoptosis) during the late stages of oogenesis, as revealed by conventional light and electron microscopy. The phalloidin-FITC staining discloses significant defects in actin cytoskeleton arrangement. The actin bundles fail to organize properly and the distribution of actin filaments in the ring canals is changed compared to the wild type. The oocyte and the chorion structures have been also modified. The oocyte nucleus is out of position and the chorion appears to contain irregular foldings, while the respiratory filaments obtain an altered morphology. The dcp-1,/,/pita,/, egg chambers do not exhibit the rare events of spontaneously induced apoptosis, observed for the wild type flies, during mid-oogenesis. Interestingly, the mutated egg chambers are protected by staurosporine-induced apoptosis in a percentage of 40%, strongly suggesting the essential role of dcp-1 and/or pita during mid-oogenesis. Cell Motil. Cytoskeleton 60:14,23, 2005. © 2004 Wiley-Liss, Inc. [source]