644 resultados para Herbst Appliance
Resumo:
Class II malocclusion features a high prevalence in Brazil, being considered as a routine in orthodontic clinics. A number of appliances are shown in the literature in order to correct Class II malocclusion with mandibular retrusion. Herbst´s fixed functional appliance, idealized by Emil Herbst (1905) and reintroduced, in the 1980´s, by Hans Pancherz is highlighted for maintaining the mandible continuously advanced, showing a shorter active treament time, an immediate esthetic impact on the facial profile, as well as requiring no patient´s commitment. Recent researches indicate the use of this appliance in individuals after pubertal growth surge. The aim of the present study is to show the orthodontics practitioner the option to use this appliance so as to treat Class II in individuals after the growth surge, obtaining satisfactory outcomes and further Class II correction.
Resumo:
This study determined the starvation tolerance of Tribolium castaneum (Herbst), Rhyzopertha dominica (F.) and Sitophilus oryzae (L.) in terms of both adult survival and reproduction, the impact of starvation on reproduction not having been studied before. Experiments were conducted at 30°C and 55% or 70% r.h. using a laboratory strain and a field strain of each species. The number of progeny was a better indicator of the impact of starvation on a species than adult survival. Tribolium castaneum was the most tolerant species, requiring up to 35 d starvation before no progeny were produced. Rhyzopertha dominica and S. oryzae required up to 8 d starvation before no progeny were produced. The results suggest that hygiene will have a greater impact on populations of S. oryzae and R. dominica than T. castaneum.
Resumo:
Tribolium castaneum (Herbst) has been used as a model organism to develop and test important ecological and evolutionary concepts and is also a major pest of grain and grain products globally. This beetle species is assumed to be a good colonizer of grain storages through anthropogenic movement of grain, and active dispersal by flight is considered unlikely. Studies using T. castaneum have therefore used confined or walking insects. We combine an ecological study of dispersal with an analysis of gene flow using microsatellites to investigate the spatiotemporal dynamics and adult flight of T. castaneum in an ecological landscape in eastern Australia. Flying beetles were caught in traps at grain storages and in fields at least 1 km from the nearest stored grain at regular intervals for an entire year. Significantly more beetles were trapped at storages than in fields, and almost no beetles were caught in native vegetation reserves many kilometres from the nearest stored grain. Genetic differentiation between beetles caught at storages and in fields was low, indicating that although T. castaneum is predominantly aggregated around grain storages, active dispersal takes place to the extent that significant gene flow occurs between them, mitigating founder effects and genetic drift. By combining ecological and molecular techniques, we reveal much higher levels of active dispersal through adult flight in T. castaneum than previously thought. We conclude that the implications of adult flight to previous and future studies on this model organism warrant consideration.
Resumo:
Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) is a common stored grain pest for which a wide range of suitable resources has been recorded. These beetles are facultatively fungivorous and their resource range may extend to fungi associated with non-grain resources (e.g. cotton seed) and other decaying plant matter. Little is known with respect to fungi in terms of resource location by these beetles in the field. We, therefore, conducted a series of experiments in laboratory arenas, glasshouse cages and the field to determine how beetles respond to grain resources in relation to cotton seed (together with its lint stubble and associated fungal flora). Results from the tests conducted in relatively small arenas and cages in the laboratory and glasshouse reveal that the responses of T. castaneum adults to food resources were twice as strong when walking as when flying (as measured by the proportion of the released beetles that were trapped). Also, a clear preference for linted cotton seeds was evident in walking T. castaneum, especially in small-scale arenas in the laboratory, where at least 60% of beetles released preferred linted cotton seeds over wheat and sorghum. Similarly, in cages (1 m3) they responded five times more strongly to linted cotton seed than to conventional grain resources. However, this pattern was not consistent with those obtained from field trapping over 20 m and the beetles did not show any particular preference to any of the resources tested above. Our results suggest a focus on walking beetles in trapping studies for population estimations and, for developing effective food-based trapping lures, the potential use of active volatiles from the fungi associated with linted cotton seed. © 2012 Elsevier Ltd.
Resumo:
The red flour beetle is a cosmopolitan pest of stored grain and stored grain products. The pest has developed resistance to phosphine, the primary chemical used for its control. The reproductive output of survivors from a phosphine treatment is an important element of resistance development but experimental data are lacking. We exposed mated resistant female beetles to 0.135 mg/L of phosphine for 48 h at 25°C. Following one week of recovery we provided two non-exposed males to half of the phosphine exposed females and to half of the non-exposed control females. Females that had been exposed produced significantly fewer offspring than non-exposed females. Females that remained isolated produced significantly fewer offspring than both exposed females with access to males and non-exposed controls (P<0.05). Some females were permanently damaged from exposure to phosphine and did not reproduce even when given access to males. We also examined the additional effects of starvation prior to phosphine exposure on offspring production. Non-exposed starved females experienced a small reduction in mean offspring production in the week following starvation, followed by a recovery in the second week. Females that were starved and exposed to phosphine demonstrated a very significant reduction in offspring production in the first week following exposure which remained significantly lower than that of starved non-exposed females (P<0.05). These results demonstrate a clear sublethal effect of phosphine acting on the female reproductive system and in some individuals this can lead to permanent reproductive damage. Pest population rebound after a fumigation may be slower than expected which may reduce the rate of phosphine resistance development. The results presented strongly suggest that phosphine resistance models should include sublethal effects. © 2012 Ridley et al.
Resumo:
The prevalence of resistance to phosphine in the rust-red flour beetle, Tribolium castaneum, from eastern Australia was investigated, as well as the potential fitness cost of this type of resistance. Discriminating dose tests on 115 population samples collected from farms from 2006 to 2010 showed that populations containing insects with the weakly resistant phenotype are common in eastern Australia (65.2 of samples), although the frequency of resistant phenotypes within samples was typically low (median of 2.3). The population cage approach was used to investigate the possibility that carrying the alleles for weak resistance incurs a fitness cost. Hybridized populations were initiated using a resistant strain and either of two different susceptible strains. There was no evidence of a fitness cost based on the frequency of susceptible phenotypes in hybridized populations that were reared for seven generations without exposure to phosphine. This suggests that resistant alleles will tend to persist in field populations that have undergone selection even if selection pressure is removed. The prevalence of resistance is a warning that this species has been subject to considerable selection pressure and that effective resistance management practices are needed to address this problem. The resistance prevalence data also provide a basis against which to measure management success.
Resumo:
During the autumn session of the ICES Advisory Committee for Fisheries Management (ACFM) 58 stocks assessed in 7 Working Groups have been analyzed and reviewed, among these the demersal stocks in the North Sea and the Mackerel stock. As in previous years, ICES recommends a reduction in fishing mortality for a number of stocks or even the establishment of recovery and management plans, to safeguard a continuous development of the stocks towards safe biological limits. ICES reiterated last year’s recommendation to close the directed cod fishery and any fishery taking cod as by-catch in the North Sea, west of Scotland and in the Irish Sea. This year, the stocks of plaice in the North Sea, southern hake and southern anglers are (among others) in a critical state and in urgent need of protecting or rebuilding measures. This will again have an enormous impact on almost all mixed fisheries in the European Union.
Resumo:
During the autumn session of the ICES Advisory Committee for Fisheries Management (ACFM) 58 stocks assessed in six Working Groups have been analysed and reviewed, among these the demersal stocks in the North Sea and the Mackerel stock in the North East Atlantic. As in previous years, ICES recommends a reduction in fishing mortality for a number of stocks or even the establishment of recovery and management plans, to safeguard a continuous development of the stocks towards safe biological limits. ICES recommended the closure of the directed cod fishery and any fishery taking cod as by-catch in the North Sea, west of Scotland and in the Irish Sea. This will have a significant impact on the mixed round fish fisheries targeting haddock and whiting.
Resumo:
Über die positive Entwicklung des Kabeljaubestandes unter Westgrönland, ab Mitte der 80iger Jahre wurde bereits im Vorjahr berichtet. Die mit FFS "Walther Herwig" im Herbst 1987 erzielten Surveyergebnisse dokumentieren einen steilen Anstieg der Bestandsgröße sowohl hinsichtlich der Individuenzahl (Abundanz) als auch des Bestandsgewichts (Biomasse) um das 4-fache auf 583 Millionen Fische bzw. um das 6-fache auf 464000 Tonnen. Diese Bestandszunahme war zahlenmäßig zu 88% und gewichtsmäßig zu 85% auf die Rekrutierung der 3 jährigen Kabeljau des starken Nachwuchsjahrganges 1984 zurückzuführen.