1,721,001 research outputs found
Use of the Proboscis Extension Response Assay to Evaluate the Mechanism of House Fly Behavioral Resistance to Imidacloprid.
Full text linkThe house fly, Musca domestica L., is a significant human and livestock pest. Experiments used female adult house flies glued onto toothpicks for controlled exposure of their tarsi alone (tarsal assay) or their tarsi and proboscis (proboscis assay) with a sucrose solution containing imidacloprid at either a low (10 µg/mL) or high (4000 µg/mL) concentration. Proboscis extension response (PER) assays were used to characterize the response of imidacloprid-susceptible and behaviorally resistant house fly strains to contact with sucrose solutions containing either a low or high concentration of imidacloprid. In each assay, 150 female flies from each fly strain were individually exposed to sucrose solutions containing either a low or high concentration of imidacloprid by deliberate contact of the fly tarsi to the test solution. The PER for each fly was subsequently recorded at 0, 2, and 10 s following the initial tarsal contact. A significant and rapid reduction in PER was observed only for the behaviorally resistant fly strain and only following contact by the flies proboscis with the sucrose solution containing the high imidacloprid concentration. The results suggest that chemoreceptors on the fly labellum or internally on the pharyngeal taste organs are involved in the detection of imidacloprid and discrimination of the concentration, resulting in an avoidance behavior (proboscis retraction) only when imidacloprid is at sufficient concentration. Further research is needed to identify the specific receptor(s) responsible for imidacloprid detection
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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Host-Seeking Activity of Culicoides sonorensis Across Seasons in Southern California and Improved Identification of Culicoides Species in the Southern California Desert
Full text linkCulicoides (Diptera: Ceratopogonidae) biting midge is a genus of small hematophagous flies that can transmit multiple disease-causing pathogens to animals and humans. In southern California, Culicoides sonorensis is the only known vector of the bluetongue virus, which is of great concern worldwide due to its rapid spread and high morbidity/mortality in ruminant animals. Investigating the diel host-seeking activity of C. sonorensis as a function of environmental conditions and exploring the overwintering mechanism of BTV will increase our knowledge of BTV transmission. It is observed that the host-seeking activity pattern of C. sonorensis varies among days and most activity starts near sunset though sometimes it starts before sunset during winter periods. The host-seeking activity pattern is influenced by weather, moon, and seasons. The relatively mild winter in southern California allows C. sonorensis to be active throughout the year, but virogenesis requires a certain temperature. Therefore, it remains unclear which mechanisms BTV is utilized for overwintering and needs further investigation. While C. sonorensis is recognized as the main vector of BTV in the southern California dairies, other Culicoides species may be important vectors of BTV to wild ruminants (e.g., bighorn sheep) in the desert regions of California. However, correct identification of these species becomes an obstacle for investigating Culicoides species-related topics in the desert area. Therefore, I develop molecular techniques combined with traditional morphological methods to identify Culicoides species in the southern California desert, which contributes to the global Culicoides taxonomy and biology. Moreover, studying the Culicoides diversity and their host preferences in the inland desert area of southern California may shed light on the relationship between Culicoides species and hemorrhagic diseases among wild ruminants and will facilitate studies of the epizootiology of hemorrhagic diseases in the area. Evaluating different trap methodologies increases the knowledge about the appropriate trapping method for targeting different Culicoides species and Culicoides of different physiological statuses in the desert region. With the sequence information, identification of immature midge species becomes easier and the abundance variation of midge species at two locations will assist future research on immature ecology
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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House Fly (Musca domestica L.) Attraction to Insect Honeydew With Identification and Behavioral Studies of Honeydew Volatile Compounds
Full text linkHouse flies are common pests on cattle feedlots and dairies, where they develop in and feed on animal waste. By contacting animal waste, house flies can acquire human pathogenic bacteria such as Escherichia coli and Salmonella spp., in addition to other bacteria, viruses, or parasites that may infect humans and animals. The subsequent dispersal of house flies from animal facilities to nearby agricultural fields containing food crops may lead to pre-harvest food contamination with these pathogens. We hypothesized that odors from honeydew, the sugary excreta produced by sucking insects feeding on crops, or molds and fungi growing on honeydew, may attract house flies, thereby increasing the risk of food crop contamination. House fly attraction to honeydew-contaminated plant material was evaluated using a laboratory bioassay and attraction was evident for the following plant-pest-honeydew combinations: citrus mealybug on squash fruit, pea aphid on faba bean plants, whitefly on navel orange and grapefruit leaves, and combined citrus mealybug and cottony cushion scale on mandarin orange leaves. Two fungal species, Aureobasidium pullulans and Cladosporium cladosporioides, were repeatedly isolated from field-collected honeydew samples. House flies were attracted to odors from A. pullulans cultures but not to those of C. cladosporioides. Gas chromatography-electroantennogram detection (GC-EAD) and gas chromatography-mass spectrometry (GC-MS) identified possible active compounds from pea aphid on faba bean plants, whitefly on navel orange, and whitefly on grapefruit leaves. 10 different compounds were identified from honeydew aeration samples that elicited a house fly antennal response. 4 of these compounds were identified from honeydew produced by whiteflies on navel orange and whiteflies on Marsh grapefruit plants, while one compound was identified from these two whitefly honeydews samples as well as honeydew from a laboratory colony of pea aphids. Two of these compounds were attractive to house flies in a blend and individually. These compound blends and single compounds were compared to fermented vinegar compounds previously found to be attractive to house flies. This dissertation presents the first study of house fly attraction to honeydew and specific honeydew odors. It contributes materially to our understanding of house fly responses to honeydew volatiles and demonstrates that insect honeydew is attractive to house flies, supporting our hypothesis that honeydew production by sucking insects infesting food crops may contribute to attraction of house flies to food crops
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Mechanisms Conferring Behavioral Resistance to the Neonicotinoid: Imidacloprid in the House Fly (Musca domestica Linnaeus)
Full text linkThe house fly (Musca domestica L.) is a cosmopolitan and synanthropic pest fly species commonly associated with confined animal facilities. It has been implicated in the transmission of over 200 different human and animal pathogens and can be extremely pestiferous in high numbers. One of the most common methods for house fly control is the use of insecticides, but insecticide resistance is an increasing problem due to over-application of insecticides and lack of rotation among insecticidal chemical classes. House fly resistance to imidacloprid, the most widely used neonicotinoid insecticide available for fly control, has evolved in field populations through both physiological and behavioral mechanisms. In this dissertation I investigated the mechanisms conferring behavioral resistance to imidacloprid.
Behavioral resistance to imidacloprid was documented to present in a field population of flies from a southern California dairy, though the resistance was not uniform among individuals in the population. Flies were selectively bred for behavioral resistance to imidacloprid, without increasing the physiological resistance profile of the selected flies. The rapid selection for behavioral resistance suggests that inheritable alleles conferring behavioral resistance were already present in the wild type fly population collected from the dairy site.
House fly behavioral resistance was further characterized using behavioral observation and feeding preference assays, with resistance determined to be both contact-dependent and specific to the insecticide (imidacloprid) rather than to a non-insecticidal component of a bait matrix as previously documented. The chromosomal location of behavioral resistance factors was then examined through the use of an autosomal linkage analysis. Behavioral resistance was mapped to autosomes 1 and 4 with inheritance of resistance being shown to be neither fully dominant nor recessive. Factors on autosomes 1 and 4 independently conferred contact-dependent avoidance and aversion of imidacloprid.
The molecular mechanisms conferring behavioral resistance to imidacloprid were then investigated using a pooled sequencing approach. In this evolve and resequence experiment we attempted to identify putative selected sites or candidate loci that may be responsible for our selected phenotype by comparing house flies that did not exhibit the behavioral resistance phenotype to house flies that exhibited a high level of behavioral resistance. While 47 genes were identified to have significant differences in SNP frequencies between the susceptible and resistant populations, these genes either had an unknown function or a reported function that is not expected to alter expression of behavioral resistance to imidacloprid. Additional fundamental and applied research should be conducted to understand further both the complex phenotypic and genotypic nature of behavioral resistance to imidacloprid
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Ecology and Management of Canyon Flies (Fannia benjamini complex) in California
Full text linkHost seeking "canyon flies" (Fannia benjamini complex) (Diptera: Muscidae) cause significant nuisance to humans and animals. To determine if a barrier trapping system using attractive traps would reduce the number of canyon flies reaching a human host within a protected area, a barrier of CO2-baited CDC-type suction traps (without light) was evaluated during the peak fly activity season at a location known for high F. conspicua Malloch activity in southern California. To select a suitable radius for the barrier, the effect of an operating CO2-baited trap on the fly capture rate of a nearby human was evaluated with traps placed at 10, 20, 30 and 40m away from the human collector. The number of flies captured by the human collector was very significantly reduced by traps placed 10m away, only slightly by traps 20m away, and unaffected by traps > 30m away. Because of site characteristics and the rapidly decreasing human-trap interaction between 10-20 m, a 15m radius circular trap barrier was erected, comprised of 8 CO2 traps. This barrier reduced F. conspicua capture by the human collector by 51 %. Reducing the barrier radius to 5m resulted in a 39 % reduction. The diel activity of F. benjamini Malloch and the "trail gnat", Amiota picta Coquillett, in the Carmel Valley, California was determined by hourly sweep net collections in September. Both species had a high activity period during early morning (0830-0930) with a second high activity period in the late afternoon and early evening (1630-1830). A. picta activity almost ceased during the inter-peak period, while F. benjamini remained active, though at reduced numbers, throughout the day. Capture rates of F. benjamini was higher at shaded locations than at sun-exposed locations. Neither the specific human collector nor the clothing color of a human collector had a significant effect on the rate of capture of F. benjamini. Substantially fewer F. benjamini were captured in a CO2 trap relative to the number captured by a human collector, even when traps were baited with the host odors ammonia and 1-octen-3-ol in addition to the CO2. The implications of these studies for management of canyon flies are discussed
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Thermal Preference of Immature House Flies (Musca Domestica) (Diptera: Muscidae)
Full text linkHouse flies are a widespread, pestiferous insect responsible for causing human nuisance as well as pathogen transmission to humans and animals. While adult fly behavior has been relatively well-studied, little is known about larval behavior. Manipulation of larval behavior may be useful to manage fly populations, reducing adult fly numbers without the need for chemical insecticides. In this study, we determined larval temperature preference by applying a temperature gradient to developmental media containing third instar fly larvae that were initially distributed evenly throughout the media. Following a 4 to 6-h assay period during which larvae could move freely within the media, larvae were found to aggregate within a relatively narrow temperature range similar to previously reported studies
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