Spelling suggestions: "subject:"arthropod"" "subject:"rthropod""
91 |
Ground - dwelling arthropods in a biosphere reserve: patterns of diversity and conservation implicationsSchoeman, Colin Stefan 17 May 2019 (has links)
PhD (Zoology) / Department of Zoology / Invertebrate diversity is often neglected in conservation planning initiatives. There are also very
few large-scale diversity studies in Africa, with most studies being restricted to single properties
and spatial extents that are on average not much larger than 30 km2. Here, we provide a
comparative regional assessment, two orders of magnitude larger than usual (30 000 km2), of
epigeal spider, beetle and millipede diversity in the Vhembe Biosphere Reserve – the largest
biosphere reserve in South Africa, and one of the largest in Africa. Firstly we aim to provide an
evaluation of the ability of a range of broad and fine scale predictors to explain the variation in the
diversity of these taxa. Secondly, we measured cross-taxon congruence between our selected
invertebrate taxa and woody vegetation, and within-taxon surrogate efficiency. Thirdly we
evaluated performance of existing and proposed zonations in representing regional invertebrate
species diversity. Finally, to aid in the development of species conservation profiles for lesser
known taxa, annotated check lists are provided for two neglected but dominant epigeal beetle
families, Tenebrionidae and Carabidae. Vegetation units explained the largest and most significant
component of beetle and spider diversity (richness and complementarity of alpha and beta
diversity). Elevation and mean annual temperature played a lesser but still significant role. Overall,
woody vegetation was a poor surrogate, especially for millipedes which have several localized
endemics. The use of higher taxa (genus and tribe in particular) shows the greatest potential for
conservation planning. The current zonation of the Vhembe Biosphere Reserve performed
significantly better than expected in representing invertebrate diversity across the region. The
reality though is that conservation decision-making is largely informed by knowledge on the
distribution of rare, localized or endangered species, for which detailed species inventories are
10
required. Though a coarse filter approach is recommended, the augmentation of species level data
provides an extra filter, and contributes to our knowledge of what taxa are in urgent need of
protection. Targeting rare and endangered species in transition zones and developing conservation
assessments and plans for these in relatively small areas would compliment existing conservation
initiatives in the VBR. Annotated check lists ofTenebrionidae of the Vhembe Biosphere suggest
that the family is particularly speciose, the assemblage being comprised of an east African and a
Kalahari element which contributes significantly to local endemicity, and yielded three new
species, one of which is described in the revision to the genus Anaxius, a group largely restricted
to the mountainous areas of Limpopo Province. Carabidae were also found to be speciose, with
the assemblage comprised of a large proportion of stenotypic species. There is support for the use
of vegetation types in conservation plans but these should be augmented with species level
conservation initiatives that target particularly transition and buffer zones. / NRF
|
92 |
Subletální efekty insekticidů neonikotinoidů na migrační a predační potenciál pavouků / Sublethal effects of the insecticides neonicotinoids on spider's migration and predatory abilitiesPřibáňová, Gabriela January 2019 (has links)
This research deals with impacts of pesticide substances on spider populations. In this case pesticides of the neonicotinoids classes were tested. Specific neonicotinoids were applied to different of spiders which were collected in various localities and at some stage of development - nymph, adult or subadult individuals. The diploma thesis analyzes and the documents the effects of neonicotinoids to spiders. The results show that some pesticides can have a significant negative effect to locomotion, predation, ballooning, drop or to spiders mortality. Keywords: spider, arthropod, pesticides, insecticides, neonicotinoids, sublethal effects, mortality, EthoVision XT, locomotion, drop, ballooning, predation, Philodromus, Oedothorax, Pardosa, Xerolycosa, Phylloneta
|
93 |
Safety and Stability of Samples Stored on Filter Paper for Molecular Arbovirus DiagnosisBringeland, Emelie January 2021 (has links)
Expanding urbanization, climate change, and population growth contribute to increased transmission and spread of arthropod-borne viruses (arboviruses), many of which cause severe disease in humans. Pathogenic arboviruses include dengue, Zika, tick-borne encephalitis, and sindbis viruses, which together threaten more than half the global population. Thus, there is a constant need for safe, specific, and sensitive molecular tests to identify early-stage infections for accurate diagnosis and molecular epidemiological data for disease prevention and control. The study tested the biosafety of using FTA™ cards when working with pathogenic arboviruses by conducting an infectivity assay using sindbis virus. Conditions for RNA extraction and storage of arboviruses on FTA were analyzed by measuring viral RNA (vRNA) stability using a SYBR-Green, Pan-Flavi RT-qPCR method composed of degenerate primers able to detect a variety of flaviviruses. Data from a Pan-Flavi RT-qPCR study comprising of 222 clinical blood and serum samples collected from a 2018 dengue virus outbreak in Hanoi (Vietnam) was analyzed to establish applicability of FTA for molecular epidemiology and diagnosis. Results showed that sindbis virus infectivity was inhibited by FTA-adsorption. FTA-adsorbed arboviruses were extracted with the highest yield using Trizol extraction and were preserved at storage at 4-20ºC for up to 30 days. The results showed that clinical blood samples acquired higher yields of vRNA for molecular testing than serum samples and that it may be possible to perform sequencing for genomic analysis. The study suggests that FTA cards may facilitate the storage and transportation of adsorbed arboviruses for downstream molecular epidemiological and diagnostic tests.
|
94 |
COLOR PRODUCTION MECHANISMS IN SPIDERS AND THEIR BIOMIMICRY POTENTIALHsiung, Bor-Kai January 2017 (has links)
No description available.
|
95 |
A study of type-3 copper proteins from arthropodsBaird, Sharon January 2007 (has links)
Arthropod hemocyanin and phenoloxidase are members of a group of proteins called the Type-3 copper oxygen-binding proteins, both possessing a highly conserved oxygen-binding site containing two copper atoms each coordinated by three histidine residues (Decker and Tuczek, 2000). Despite similarities in their active site, these proteins have very different physiological functions. Phenoloxidase possesses both tyrosinase and o-diphenoloxidase activity, and is predominantly involved in reactions which protect insects from infection (Kopàcek et al., 1995). Hemocyanin is a large multi-subunit protein with a primary function as a respiratory protein, reversibly binding and transporting molecular O2 (Decker and Rimke, 1998; Decker and Tuczek, 2000). Recently, it has been demonstrated in vitro that arthropod hemocyanin possesses an inducible phenoloxidase activity when incubated with denaturants, detergents, phospholipids or proteolytic enzymes. This activity appears to be restricted to only a few subunit types, and it has been hypothesised that it may be accompanied by conformational change which opens the active site increasing access for larger phenolic substrates (Decker and Jaenicke, 2004; Decker et al., 2001; Decker and Tuczek, 2000). This possibly suggests a dual role of hemocyanin in arthropods. The presented thesis deals with two distinct aims. The first was to isolate and sequence a phenoloxidase gene from the insect Spodoptera littoralis (Egyptian Cottonleaf Worm). Despite efforts, progress was hindered by a number of experimental problems which are outlined within the relevant chapters. The second aim was to characterise the mode of SDS induced phenoloxidase activity in arthropod hemocyanin from the ancient chelicerates Limulus polyphemus (horseshoe crab) and Eurypelma californicum (tarantula) and the more modern chelicerate Pandinus imperator (scorpion), using a number of biophysical techniques. The results indicated that the SDS induced phenoloxidase activity is associated with localised tertiary and secondary conformational changes in hemocyanin, most likely in the vicinity of the dicopper centre, thus enhancing access for larger phenolic substrates. Experiments indicate that copper remains associated with the protein during these structural changes; however the nature of the association is unclear. SDS concentrations approximating the CMC appeared critical in causing the necessary structural changes required for a significant increase in the detectable phenoloxidase activity to be exhibited.
|
96 |
Development of fungal biological control of four agriculturally important pests, Sitophilus oryzae, Trialeurodes vaporariorum, Planococcus ficus and Eldana saccharina, in South Africa.Chambers, Craig Brian. January 2005 (has links)
The use of entomopathogenic fungi to control agriculturally important pests, both in
greenhouses and in the field, has been demonstrated by various authors for a number of
years. This has been brought about by the development of resistance in certain pest
species to chemical applications and a growing public awareness of the safety
implications of residual insecticides. Several entomopathogenic fungi were tested
against four insect pests found in the Republic of South Africa (RSA), the greenhouse
whitefly, Trialeurodes vaporariorum, the rice weevil, Sitophilus oryzae, the grapevine
mealybug, Planococcusficus and the sugarcane stem borer, Eldana saccharina. Further
concentration, temperature and humidity studies were conducted with selected isolates
on the rice weevil, S. oryzae.
Sitophilus oryzae is considered one ofthe most important pests of stored grain. Several
fungal isolates were tested against the rice weevil, four of which, B1, PPRI 6690, PPRI
6864 and PPRI 7067, were selected for further testing based on the mortality results over
a 21 d period. Varying conidial concentrations were applied and at high doses of 1x10 -6
conidia ml -1 with mortality rates of to 84% achieved. LT 50 values ranged from 6 - 68d.
Increased spore concentration resulted in an increase in overall mortality.
Temperature and humidity was found to affect the infection potential of the four isolates
tested. Four temperatures ranging from 15 - 30°C were tested. The highest mortality
rates were obtained at 25°C where mortality ranged from 46 - 65% in 14d. Mortality
rates decreased with decreasing temperature, and no mortality was recorded at 30°C.
Temperature was found to significantly alter the LT 50 values, increasing the LT 50 with
decreasing temperatures. Decreasing the humidity resulted in an increased LT 50 and a
reduction in the overall mortality rates. The mortality of S. oryzae ranged according to
the RH and isolate. Isolates Bland PPRI 6690 resulted in the highest mortalities of 80
and 83% at 92.5% RH, with LT 50's of 6.3d and 6.4d, respectively.
Several entomopathogenic fungi were tested against T vaporariorum, P. ficus and E.
saccharina, three key pests of South African crops. Nine fungal isolates were tested
against the greenhouse whitefly, T vaporariorum, with mortalities ranging from 26.7 - 74.7% over 14d. Beauveria bassiana Isolates Bl and PPRl 6690 produced the highest
mortality rates and were recommended for further pathogenicity testing against T.
vaporariorum.
Planococcus ficus is a common pest ofvineyards in the Western Cape Province, South
Africa. Nine entomopathogenic fungi were screened against P.ficus, only two of which
produced mortality. Eldana saccharina is a stalk borer, which infests sugarcane in large
areas of Southern Africa. Five isolates were tested against second and third instar larvae,
three of which, B1, PPRl 6864 and PPRl 6690 resulted in mortalities. Mean percentage
mortality was low for all three isolates.
From the study it was evident that two of the isolates tested, Bland PPRI 6690 (B.
bassiana), showed potential against three of the four pests, and two isolates of
Lecanicillium lecanii caused mortality in P. ficus. Further research and understanding of
the effect of environmental conditions, spore concentration and epizootic potential
would result in the further development of these isolates as future biological control
agents. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.
|
97 |
Design, expression and purification of virus-like particles derived from metagenomic studies : Virus-like Particles (VLP) of novel Partitiviridae species, Hubei.PLV 11, and novel Soutern pygmy squid flavilike virus were designed, expressed using the bac-to-bac expression system and then pruified using various methodsAyranci, Diyar January 2021 (has links)
Viruses are entities which are made of a few genes and are reliant on obligate parasitism to propagate. Due to the obligate connection to their hosts, virus evolution is constrained to the type of host. Viruses however do transmit to evolutionary distinct hosts; in these cases, the phylogenetic relationship of the hosts usually are close. In some instances, RNA-viruses have made host jumps between evolutionary distant hosts, such as the host jump from invertebrates to vertebrates, and fungi to arthropod. Partitiviruses are double stranded RNA viruses which mainly infect fungi and plants. The defining characteristic of these double stranded RNA viruses are the double layered capsids which are formed by a single open reading frame (ORF). The capsid proteins form icosahedral virus particles which are in the magnitude of 30-40 nm. Metagenomic studies have discovered partitiviruses originating from an insect in the Odanata family, a finding which contradicts the fungal host specificity of partitiviruses. The finding of the Hubei.PLV 11 thus implies the existence of a partitiviruses containing structural elements in their capsids which could be involved in the infection of arthropods. Thus, this virus could be used as a model for a structural comparison with its fungi infecting relatives with hopes to identify common viral structural factors necessary for the infection of arthropods. For this purpose, the Hubei.PLV ORF was cloned and then transfected into insect Spodoptera frugiperda (Sf-9) cells using a baculovirus expression system, “bac-to-bac” expression system. The FLAG-tagged capsid proteins were expressed by the Sf-9 cells to be approximately 60 kDa. After ultra-centrifugation in a sucrose gradient, some spontaneous assembly into the expected ~40 nm icosahedral virus-like particles were observed using low resolution scanning electron microscopy. The observed particles were also confirmed by a dynamic light scattering experiment (DLS) and a higher resolution cryo-EM microscope. Thus, the bac-to-bac expression system can be used to produce VLPs from this genus of viruses, and this metagenomically derived virus genome. However, for future success in defining a high-resolution model of this virus, it is recommended that the Sf-9 culture volume is sufficiently high for enough particle production which is necessary for a high-resolution map. The other virus, the Southern pygmy squid Flavilike virus (SpSFV) has been suggested to be the oldest relative of the land based flaviviruses. The SpSFV was found to be the most divergent of the flaviviruses, and to infect invertebrates. Solving for the structure of the SpSFV and comparing it to vertebrate infecting flaviviruses could therefore lead to the identification of factors necessary for the adaptation to vertebrates and thus the humoral immunity by flaviviruses. The soluble E-protein was expressed using the bac-to-bac expression system. The protein was indicated to be multiglycosylated and approximately 50 kDa which is in line with other strains in the genus. Affinity chromatography did not elute this protein, likely due to the His-tag not being spatially available. Cation exchange could elute some protein, but not much from the small ~30 mL culture. To conclude, VLP assembly was confirmed by the Hubei.PLV, thus, solving for the structure is a distinct possibility when a larger Sf-9 culture is used to produce the VLPs. For the SpSFV soluble E-protein, the protein is secreted into the supernatant of the Sf-9 cultures, making purification a possibility. For this, a large Sf-9 culture can be used to produce this protein and then purify it with a cat-ion exchange chromatography.
|
98 |
Birds, bats and arthropods in tropical agroforestry landscapes: Functional diversity, multitrophic interactions and crop yieldMaas, Bea 20 November 2013 (has links)
No description available.
|
Page generated in 0.0348 seconds