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Epidemiology and crop loss assessment of rice nematodes in West AfricaCoyne, Daniel L. January 1999 (has links)
No description available.
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Determining the effect of polluted mine water on the ecosystem health of a karstic cave environment in the Witwatersrand Basin / Gerhard Cornelis du PreezDu Preez, Gerhard Cornelis January 2014 (has links)
The Wonderfontein Cave is located within the Witwatersrand Basin (Gauteng province,
South Africa) and is associated with the river banks of the Wonderfontein Spruit. This cave
system has for many years been subjected to the influx of polluted mine water. Since
subterranean environments remain poorly studied, it is unknown what the effect of this might
be on the associated ecosystem. Furthermore, water that enters the Wonderfontein Cave
poses a severe health threat as it drains into the underlying aquifer, which is abstracted for
human and animal use. The general aim of this study was to determine the extent of metal
pollution (enrichment), as well as to study the toxicity hazard potential of the soils and
sediments associated with the Wonderfontein Cave. The objectives of this study were to (1)
quantify the extent of anthropogenic metal pollution of water, soils and sediments associated
with the Wonderfontein Cave (2) and assessing the toxicity hazard potential of these
substrates; (3) determining whether nematode taxa and C. gariepinus individuals represent
isolated communities and a population within the Wonderfontein Cave, respectively; (4)
measuring the effect of mining-associated pollutants on the soil and sediment health of the
Wonderfontein Cave by making use of nematodes to serve as bioindicators; (5) evaluating
and comparing biomarker responses to metal bioaccumulation in C. gariepinus populations
associated with the Wonderfontein Cave and epigean (surface) environments and lastly (6)
comparing the results of the above identified assessments over both a temporal and spatial
scale. Sampling was undertaken during April (1st sampling interval) and September (2nd
sampling interval) 2013, which respectively represented the end of the high and low flow
periods. Also, sampling of the subterranean (Wonderfontein Cave) and associated surface
(Wonderfontein Spruit) environments were undertaken. The findings of this study suggested
that especially the sediments associated with the Wonderfontein Cave have been subjected
to severe nickel, copper, zinc, cobalt, aluminium, cadmium, lead and uranium enrichment.
Also, the concentrations of many of the studied metals exceeded the respective water, soil
and sediment environmental quality guidelines. Thus, also taking into consideration that
most of the sediments were classified as being toxic, a severe threat is posed to the health
of the associated biota. Although 60 nematode genera were identified from soil and
sediments samples collected from the respective sampling sites associated with the
Wonderfontein Cave and Spruit, it was concluded that most of these genera were likely only
temporary residents of the subterranean environment. Even though plant-parasitic and nonparasitic
nematodes were present, most of the collected soil and sediment samples were
dominated by bacterivores (non-parasitic nematodes). Zero genetic divergence was
recorded between the C. gariepinus populations associated with the Wonderfontein Cave and Stoffels Dam (Wonderfontein Spruit). However, significant temporal and spatial variation
was observed in some bioaccumulated metals and biomarker responses within and between
the respective C. gariepinus populations. Furthermore, the metal bioaccumulation levels
present in both these fish populations pose a substantial threat to human health and are
thus not fit for consumption. Also, no significant fish condition differences were observed
between the C. gariepinus populations associated with the Wonderfontein Cave and Spruit.
This study served as an initiative to create awareness and promote the conservation of
Africa’s karst landscapes. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015
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Determining the effect of polluted mine water on the ecosystem health of a karstic cave environment in the Witwatersrand Basin / Gerhard Cornelis du PreezDu Preez, Gerhard Cornelis January 2014 (has links)
The Wonderfontein Cave is located within the Witwatersrand Basin (Gauteng province,
South Africa) and is associated with the river banks of the Wonderfontein Spruit. This cave
system has for many years been subjected to the influx of polluted mine water. Since
subterranean environments remain poorly studied, it is unknown what the effect of this might
be on the associated ecosystem. Furthermore, water that enters the Wonderfontein Cave
poses a severe health threat as it drains into the underlying aquifer, which is abstracted for
human and animal use. The general aim of this study was to determine the extent of metal
pollution (enrichment), as well as to study the toxicity hazard potential of the soils and
sediments associated with the Wonderfontein Cave. The objectives of this study were to (1)
quantify the extent of anthropogenic metal pollution of water, soils and sediments associated
with the Wonderfontein Cave (2) and assessing the toxicity hazard potential of these
substrates; (3) determining whether nematode taxa and C. gariepinus individuals represent
isolated communities and a population within the Wonderfontein Cave, respectively; (4)
measuring the effect of mining-associated pollutants on the soil and sediment health of the
Wonderfontein Cave by making use of nematodes to serve as bioindicators; (5) evaluating
and comparing biomarker responses to metal bioaccumulation in C. gariepinus populations
associated with the Wonderfontein Cave and epigean (surface) environments and lastly (6)
comparing the results of the above identified assessments over both a temporal and spatial
scale. Sampling was undertaken during April (1st sampling interval) and September (2nd
sampling interval) 2013, which respectively represented the end of the high and low flow
periods. Also, sampling of the subterranean (Wonderfontein Cave) and associated surface
(Wonderfontein Spruit) environments were undertaken. The findings of this study suggested
that especially the sediments associated with the Wonderfontein Cave have been subjected
to severe nickel, copper, zinc, cobalt, aluminium, cadmium, lead and uranium enrichment.
Also, the concentrations of many of the studied metals exceeded the respective water, soil
and sediment environmental quality guidelines. Thus, also taking into consideration that
most of the sediments were classified as being toxic, a severe threat is posed to the health
of the associated biota. Although 60 nematode genera were identified from soil and
sediments samples collected from the respective sampling sites associated with the
Wonderfontein Cave and Spruit, it was concluded that most of these genera were likely only
temporary residents of the subterranean environment. Even though plant-parasitic and nonparasitic
nematodes were present, most of the collected soil and sediment samples were
dominated by bacterivores (non-parasitic nematodes). Zero genetic divergence was
recorded between the C. gariepinus populations associated with the Wonderfontein Cave and Stoffels Dam (Wonderfontein Spruit). However, significant temporal and spatial variation
was observed in some bioaccumulated metals and biomarker responses within and between
the respective C. gariepinus populations. Furthermore, the metal bioaccumulation levels
present in both these fish populations pose a substantial threat to human health and are
thus not fit for consumption. Also, no significant fish condition differences were observed
between the C. gariepinus populations associated with the Wonderfontein Cave and Spruit.
This study served as an initiative to create awareness and promote the conservation of
Africa’s karst landscapes. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015
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The role of cover crops with biofumigation potential for the suppression of plant-parasitic nematodes in vineyardsKruger, Daniel Hendrik Michau 12 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Plant-parasitic nematodes, consisting of a wide range of species, can cause severe economic
losses in most agricultural food crops. Meloidogyne spp. (root-knot nematodes), Criconemoides
xenoplax (ring nematode), Xiphinema index (dagger nematode) and Pratylenchus spp. (lesion
nematodes) are some of the economically important plant-parasitic nematodes that pose a threat to
viticulture and other perennial crops in South Africa. Worldwide there is ever-increasing pressure on
pre-plant synthetic soil fumigants and post-plant nematicides. For sustainable nematode
management, it is important to have a holistic approach; taking into consideration cultural, biological
and chemical options as part of an integrated management approach.
Biofumigation has the potential to fit into such an integrated management system and
previous research indicates the positive response on soil-borne diseases, nematodes and weeds.
Biofumigation occurs where certain plant species, containing glucosinolates (GSL) in the vacuole of
the plant cells, come into contact (after cell maceration), with the enzyme myrosinase (MYR) situated
in the cytoplasm of the cell, to form active compounds such as isothiocyanate (ITC). When this green
manure is applied to infested soil, the ITC has the potential to have a direct suppressive effect on the
soil-borne pathogens and there is also an indirect effect that can be expected after green manure soil
amendment, because microbial activity is enhanced in the soil. Brassicas are known to possess GSL
and MYR in their cells and thus have the potential to be utilized as biofumigation crops. There are,
however, differences in the potential within the Brassicaceae family, based on different types and
concentrations of GSL present in the different species. To ensure effective biofumigation it is
important to use the correct brassica species and have a good understanding of the factors that have
a positive impact on the biofumigation action.
Laboratory bioassays were done to determine the potential of different cover crops to
suppress Meloidogyne javanica and C. xenoplax, when applied as a green manure. The cover crops
used for the bioassays included Oats (Avena sativa cv. Pallinup), White mustard (Sinapis alba cv.
Braco), Canola (Brassica napus cv. AV Jade), Caliente 199 (Brassica juncea cv. Caliente 199) and
Nemat (Eruca sativa cv. Nemat). The plant material was cut into small pieces and mixed with
sterilised soil inoculated with either M. javanica or C. xenoplax. Results from the bioassays showed a
significant suppression of M. javanica by the three biofumigation species: White mustard, Caliente 199 and Nemat. These results supported previous research, indicating the nematode suppressing
effect due to the biofumigation action of certain brassica crops. Canola did not have the same
suppressing impact on the M. javanica and gave comparable results to the control, indicating that
Canola is not a good biofumigation crop for M. javanica suppression. In terms of biofumigation effect
oats did not differ significantly from the control or the three brassicas: White mustard, Caliente 199
and Nemat. In the bioassays done for C. xenoplax no significant differences were found between the
green manure treatments and the control. These results indicate that the different crops tested,
including the three well known biofumigation crops, did not suppress the C. xenoplax at the applied
biomass concentrations used in the bioassay.
Crops can also be classified according to their host status for certain plant parasitic
nematodes. Crop host trials were conducted to determine the crop host status of the five different
cover crops, to M. javanica and C. xenoplax. The crops were planted in sterilised soil, inoculated with
the latter plant-parasitic nematodes and left for 60 days, after which, a root gall index analysis was
done for M. javanica and for 85 or 92 days after which C. xenoplax was extracted from the soil. All the
crops evaluated had a significantly lower root gall index for M. javanica than the control. Nemat and
Oats was classified as poor hosts for M. javanica. A visual inspection of the root systems of all the
crops was performed to determine whether M. javanica managed to complete its lifecycle in the
different root systems. On all root systems, M. javanica managed to form root galls and produce egg
masses, from which (J2) juveniles emerged. This indicates that M. javanica did complete its lifecycle
in the different root systems of the crops evaluated and that all the cover crops acted as hosts. The
expression of the gall symptoms were, however, less severe on Nemat and Oats, compared to the
others. In the C. xenoplax crop host trials, all except the Nemat treatment showed a significant
difference, compared to the Tomato treatment, with lower C. xenoplax numbers being present in the
other crops. The nematode numbers in the different crops, compared well with the control (only
inoculated soil), indicating that the crops did not stimulate the reproduction of C. xenoplax. Canola
had the lowest numbers of C. xenoplax present after the growing cycle and Caliente 199 also showed
a declining trend.
In South Africa, the use of annual cover crops in vineyards is an established soil cultivation
practice. In a field study, Oats, White mustard, Canola, Caliente 199 and Nemat were established in a
vineyard as cover crops for three growing seasons (2009/10, 2010/11, 2011/12), and evaluated for their biofumigation impact, as well as their host impact on the suppression of certain economically
important plant-parasitic nematodes. Two cover crop management practices, namely mechanical
incorporation (MC) into the top soil and chemical removal of the cover crop (CC) were applied to the
different cover crops. Nematode samples were taken in the work row and in the vine row at different
times to determine the nematode status. These periods were April/May, before planting the cover
crops, as well as 0, 15, 30 and 60 days after the management practices were performed. The crop
biomass, measured as dry matter production (DMP) in tons/ha, differed significantly between the
different crops, but also showed substantial increases during the three cover crop growing seasons
for most crops. During the three consecutive seasons, Canola (CC) and Caliente 199 (CC) showed a
constant reduction in the C. xenoplax population in the vine row based on the 60 day analysis. This
trend was also observed for the total plant-parasitic nematode population in the vine row for the three
seasons, based on 60 day analysis. The same trend took place during the three-year trial period for
all the different sampling periods (0, 15, 30 and 60 days). The results can be attributed to the host
status of these crops and not primarily because of the biofumigation effect. Both the Canola (CC) and
the Caliente (CC) had a substantial increase in DMP during the three growing seasons that might
have played a role in this trend. White mustard (CC and MC) showed a significant increase in the C.
xenoplax population in the vine row, over the three year period, based on the 60 day analysis. The
same trend was found Nemat (CC) and weeds and nematicide (CC) measured at the same period. A
positive result from the Meloidogyne sp. analysis was that there was no significant increase in the
Meloidogyne sp. in the vine row during the three growing seasons based on the 60 day analysis. This
trend was seen in all the different treatments. The results from this study opens the possibility to apply
these cover crops as part of a crop rotation programme without expecting an increase in the
Meloidogyne sp. population to occur in the vine row through time. / AFRIKAANSE OPSOMMING: Plantparasitiese nematodes, wat bestaan uit 'n wye verskeidenheid van spesies, kan lei tot
ernstige ekonomiese verliese in die meeste landbou gewasse. Meloidogyne spp. (knopwortel
nematode), Criconemoides xenoplax (ring nematode), Xiphinema index (dolk nematode) en
Pratylenchus spp. (letsel nematode) is van dié belangrikste plantparasitiese nematodes wat 'n
bedreiging inhou vir wingerd en ander meerjarige gewasse in Suid-Afrika. Wêreldwyd is daar tans
toenemende druk op die uitfasering van voor-plant chemiese grondberoking middels en so ook op nauitplant
nematisiede. Vir volhoubare nematode bestuur, is dit belangrik om 'n holistiese benadering te
volg, in ag genome kulturele, biologiese en chemiese maatreëls as deel van 'n geïntegreerde
benadering. Bioberoking het die potensiaal om deel uit te maak van so 'n geïntegreerde benadering
en baie vorige navorsing bevestig hierdie positiewe reaksie, in terme van onderdrukking, wat
bioberoking op grond-gedraagde siektes, nematodes en onkruid kan hê. Bioberoking kan beskryf
word as die reaksie, wat plaasvind wanneer glukosinolaat (GSL), wat teenwoordig is in die vakuool
van die plantselle, in kontak kom met die ensiem mirosinase (MYR), nadat selbreking plaasgevind het
en die aktiewe verbinding isothiosianaat (ITC) en ander sekondêre metaboliete gevorm word.
Wanneer hierdie groen plantmateriaal in die grond ingewerk word, kan ʼn direkte onderdrukkings effek,
as gevolg van die ITC, asook ʼn indirekte onderdrukkings effek as gevolg van die stimulasie van
mikrobe aktiwiteit, verwag word. Brassica gewasse is bekend daarvoor dat daar GSL en MYR in die
plantselle teenwoordig is en hulle besit dus die potensiaal om ITC te vorm. Daar is egter verskille in
hierdie potensiaal binne die Brassicaceae familie, wat gebaseer is op verskillende tipes en
konsentrasies GSL. Die keuse van ʼn brassica spesie is dus belangrik, tesame met ʼn verskeidenheid
van ander faktore, om optimale bioberoking te verseker.
Laboratorium biotoetse is gedoen om die bioberokings effek van verskillende dekgewasse op
Meloidogyne javanica en C. xenoplax, wanneer dit aangewend word as groenbemesting, te bevestig.
Die dekgewasse wat gebruik is sluit in: Hawer (Avena sativa cv. Pallinup), Wit mosterd (Sinapis alba
cv. Braco), Canola (Brassica napus cv. AV Jade), Caliente 199 (Brassica juncea cv. Caliente 199) en
Nemat (Eruca sativa cv. Nemat). Die plantmateriaal is fyn opgesny en ingewerk in gesteriliseerde
grond wat met onderskeidelik M. javanica en C. xenoplax geïnokuleer is. Resultate van die biotoetse
vir M. javanica toon dat die drie gewasse; Wit mosterd, Caliente 199 en Nemat, wat alombekend is vir
hul bioberoking potensiaal, ʼn betekenisvolle onderdrukkings op M. javanica tot gevolg gehad het. Hierdie biotoetse ondersteun vorige navorsing, waar effektiewe onderdrukking van sekere
Meloidogyne spesies as gevolg van bioberoking verkry is. Die resultate dui ook aan dat Canola nie ʼn
goeie opsie is vir effektiewe bioberoking om M. javanica onderdrukking te verkry nie. Die Hawer
behandeling het nie betekenisvol van die kontrole of van die ander bioberokings gewasse verskil nie.
Daar is geen betekenisvolle verskille verkry tussen die kontrole en die ander gewasse tydens die C.
xenoplax biotoetse nie. Die resultate dui aan dat die dekgewasse, insluitende die drie bekende
bioberokings gewasse, nie C. xenoplax onderdruk teen die toegediende biomassa konsentrasies nie.
Gewasse kan ook geklassifiseer word op grond van hul gasheer status vir sekere nematode.
Gasheer toetse is gedoen om die gasheer status van die verskillende dekgewasse vir M. javanica en
C. xenoplax te bepaal. Dieselfde vyf verskillende dekgewasse is geplant in grond, wat vooraf
onderskeidelik met M. javanica en C. xenoplax geïnokuleer is. Plante is gelos om vir `n spesifieke
periode te groei waarna ʼn galindeks evaluasie is gedoen om die gasheer status vir M. javanica te
bepaal en ʼn nematode ontleding gedoen is om die gasheer status vir C. xenoplax te bepaal. In die M.
javanica gasheer toetse was die galindeks van al die gewasse betekenisvol laer as die kontrole.
Nemat kan geklassifiseer word as ʼn swak gasheer vir M. javanica en het betekenisvol minder galle as
al die ander gewasse, behalwe die Hawer, waarvan dit nie betekenisvol verskil het nie. Nemat pas
dus goed in ʼn dekgewas program waar die doel is om die M. javanica populasie te onderdruk tydens
die groei van die gewas. ʼn Visuele inspeksie van die wortelstelsels is ook gedoen ten einde te bepaal
of die lewensiklus van M. javanica voltooi is. Wortelgalle en eiersakkies was teenwoordig in die
wortels van al die verskillende gewasse en larwes het uit die eiers uitgebroei. Dit dui aan dat M.
javanica daarin geslaag het om sy lewenssiklus op al die dekgewasse suksesvol te voltooi. Daar was
aansienlik minder eiersakke by Nemat en Hawer; wat hul swak gasheer status bevestig. In die
biotoetse vir die gasheerstatus van C. xenoplax het al die gewasse, behalwe Nemat, betekenisvol
laer C. xenoplax getalle, in vergelyking met die Tamatie behandeling, tot gevolg gehad. Die nematode
getalle was soortgelyk aan die kontrole (slegs geïnokuleerde grond), waar geen gewas in medium
geplant is nie, en dui dus aan dat die getalle op die verskillende gewasse nie vermeerder het nie. Die
Canola behandeling het die laagste C. xenoplax getalle gehad, gevolg deur Caliente 199. Hierdie
gewasse toon dus die meeste potensiaal om aangewend te word in 'n rotasie stelsel of dekgewas
program, waar die doel is om die C. xenoplax populasie te onderdruk. In Suid-Afrika is die aanwending van spesifieke eenjarige gewasse, as dekgewasse in
wingerde, reeds ʼn standaard praktyk met verskeie voordele. In veldproewe oor ʼn tydperk van drie jaar
(2009/10, 2010/11, 2011/12) is Hawer, Wit mosterd, Canola, Caliente 199 en Nemat aangeplant as
dekgewasse in ʼn wingerd proefperseel. Die doel van die veldproewe was om die effek van
dekgewasse op die plantparasitiese nematodes, wanneer dit aangewend word as bioberokings
gewasse, te bepaal. Die gasheer status van die gewasse is ook ondersoek om te bepaal wat die effek
sal wees op die nematode getalle. Twee dekgewas bestuurspraktyke is toegepas; meganiese inwerk
van die dekgewasse in die bogrond (MC) en chemiese beheer van die dekgewasse (CC) en
nematode monsters is op verskillende tye in die werksry en in die wingerdry geneem. Hierdie
periodes sluit in April/Mei, voor die vestiging van die dekgewasse en 0, 15, 30 en 60 dae nadat die
bestuurspraktyk toegepas is. Die dekgewas se biomassa produksie is, op grond van die droë massa
produksie (DMP), in ton/ha gemeet, wat betekenisvol verskil het vir die verskillende dekgewas. Daar
het ook `n duidelike toename in DMP plaasgevind oor die drie seisoene vir meeste gewasse.
Gedurende die drie jaar periode het die Canola (CC) en Caliente 199 behandelings, gemeet 60 dae
na die bestuurspraktyk, ʼn konstante afname getoon in die C. xenoplax in die wingerd ry. Dieselfde
tendens het ook voorgekom gedurende hierdie periode in die totale plantparasitiese nematodes
teenwoordig in die wingerd ry. Daar is ook ʼn geleidelike afnemende tendens in die C. xenoplax in die
wingerd ry, oor die verskillende periodes 0, 15, 30 en 60 dae vir die drie opeenvolgende seisoene,
waargeneem. Hierdie resultate kan primêr toegeskryf word aan die gasheer status van die
dekgewasse, wat in die gasheer proewe as swak gashere vir C. xenoplax aangetoon is. Nog ʼn faktor
wat hier ʼn rol speel is die feit dat beide die Canola (CC) en die Caliente 199 (CC) ʼn toename in DMP
van meer as 2 ton, gedurende die drie jaar periode, gehad het; wat op sigself ook ʼn bydraende rol
kon speel. Wit mosterd (CC en MC) het oor die drie seisoene ʼn betekenisvolle verhoging in die C.
xenoplax populasie tot gevolg gehad, gebaseer op die 60 dae ontleding. Dieselfde tendens is ook
opgemerk vir die ander behandelings, onder andere Nemat (CC) en die onkruid en aalwurmdoder
(CC) behandeling. ʼn Baie positiewe resultaat na afloop van die drie seisoene is die feit dat daar nie ʼn
betekenisvolle verhoging in die Meloidogyne sp. populasie in die wingerdry, op grond van die 60 dae
onledings, plaasgevind het nie. Dit was ook die geval vir al die ander behandelings. Hierdie resultate
ondersteun die moontlikheid om hierdie bioberokings gewasse deel te maak van ʼn geïntegreerde
dekgewas benadering, sonder om in die proses die Meloidogyne sp. in die wingerd ry te verhoog.
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Entomopathogenic Nematodes: Their Interactions with Plant Pathogens and Insecticides in the SoilNavarro, Patricia D. January 2012 (has links)
Entomopathogenic nematodes (EPNs) in the families Heterorhabditidae and Steinernematidae, and their bacterial symbionts, have been studied intensively because of their role as natural mortality factor for soil-dwelling arthropods, and their potential as biological control agents for belowground insect pests. Moreover, EPN are recognized as key players in regulating soil food webs and triggering trophic cascades. However, most studies of interactions with EPN have been conducted under laboratory setting and simplified conditions, without consider the dynamic of the EPN and their interactions with other soil components in a wider context. In this respect, knowledge of the effect that other soil organisms or human induced factor may have on EPN dynamic and life cycle in the soil may contribute to improve tactics for their implementation and success as natural regulators of herbivores. The present investigation focused on the interactions of EPN with a selection of insecticides, and biotic (saprobic fungus and plant parasitic nematodes) elements that may be present in the soil, and may potentially interact with EPN. Specifically, I investigated how these factors may affect the life cycle (host search behavior, virulence and reproduction) of EPN. Appendix A shows the effect that a group of selected synthetic and biological insecticides have on EPN virulence and reproduction. The results obtained from this study revealed that most combinations of EPN and insecticides under study increased the mortality of the insect host. However, it was also found that some of these combinations reduced the nematode progeny production and emergence of IJs from the insect cadaver. In contrast in Appendix B, when examining the effect of the saprobic fungus Fusarium oxysporum in the life cycle of the EPN Heterorhabditis sonorensis, it was found that this fungus negatively affected the virulence and reproduction of the EPN in the insect host. In the third study of this dissertation (Appendix C) the interactions studied considered the effect of two EPN on an organism of a different trophic guild, the plant parasitic nematode Tylenchulus semipenetrans. This plant parasitic nematode causes serious diseases in citrus plants by infecting their roots and defoliating their branches. Previous studies have shown that some EPN species may negatively affect the life cycle of plant parasitic nematodes by reducing the damage produced by this plant parasite. Results from this study confirm the antagonistic effect between the selected EPN and the citrus nematode. Specifically, it was found that the presence in the soil of both EPN reduced the survival of infective juveniles of the citrus nematode and their penetration to the root. Moreover, the presence of EPN had an antagonistic effect in the production of eggs of T. semipenetrans females.
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Levantamento, reprodução e patogenicidade de nematóides a fruteiras de clima subtropical e temperado. / Field survey, reproduction and pathogenicity of nematodes to subtropical and temperate fruits.Rossi, Carlos Eduardo 18 April 2002 (has links)
Objetivando melhor conhecimento a respeito dos nematóides encontrados associados a fruteiras de clima subtropical e temperado, coletaram-se 149 amostras de solo da rizosfera e de raízes de amoreira-preta, caquizeiro, framboeseira, macieira, marmeleiro, nespereira, nogueira-macadâmia, oliveira, pereira, pessegueiro e umezeiro em áreas de produção do Estado de São Paulo e em uma localidade de Minas Gerais. Como resultado desse levantamento, identificaram-se 11 gêneros e as espécies relacionadas a seguir: Aorolaimus nigeriensis, Discocriconemella degrissei, Helicotylenchus dihystera, H. erythrinae, H. microcephalus, H. pseudorobustus, Helicotylenchus spp., Hemicycliophora poranga, Meloidogyne hapla, M. incognita, M. javanica, Mesocriconema onoense, M. ornata, M. sphaerocephalum, M. xenoplax, Mesocriconema spp., Pratylenchus brachyurus, P. zeae, Rotylenchulus reniformis, Scutellonema brachyurus, Tylenchulus semipenetrans, Xiphinema brevicollum, X. elongatum, X. krugi, X. setariae, X. surinamense e Xiphinema spp.. Os três gêneros mais freqüentes foram Helicotylenchus, Mesocriconema e Xiphinema, presentes em 60,4; 55,0 e 30,2 % das amostras, respectivamente; as espécies mais comuns foram H. dihystera e M. xenoplax, ocorrendo em 49 e 38,3 % das amostras. Contudo, apenas M. incognita e M. javanica estavam associados a danos em pessegueiros cujos porta-enxertos não tinham resistência genética. Em casa de vegetação, avaliaram-se as reações de genótipos das citadas fruteiras, mais goiabeira, frente aos nematóides de galhas Meloidogyne incognita raça 2 e M. javanica. As plantas, individualmente inoculadas com 5000 ovos de cada espécie de nematóide, foram conduzidas em recipientes plásticos durante 120 dias. A caracterização das reações baseou-se na capacidade reprodutiva dos parasitos, determinando-se os índices de massas de ovos e de galhas, bem como os números de nematóides por sistema radicular e por grama de raízes. Apenas a cultivar GF-677 de Prunus persica x P. dulcis comportou-se como suscetível, possibilitando desenvolvimento e multiplicação dos dois nematóides. Os demais genótipos avaliados foram hospedeiros desfavoráveis ao desenvolvimento dos nematóides, sendo considerados resistentes, embora vários deles tivessem proporcionado restritas taxas de reprodução dos parasitos. Estudou-se ainda, também sob condição de casa de vegetação, a patogenicidade de M. incognita raça 2 em caquizeiro 'Kyoto', verificando-se correlação negativa entre os níveis populacionais iniciais utilizados (0, 160, 800, 4 000, 20 000 e 100 000 ovos por parcela) e a altura e a massa seca de raízes das plantas, após seis meses da inoculação. Tendo em vista que a intensa formação de galhas radiculares observada e o efeito negativo sobre os dois parâmetros de crescimento das plantas mostraram-se associados a taxas de reprodução muito baixas do parasito, considerou-se que a reação ocorrida foi de intolerância. / In order to achieve a better knowledge on the nematodes found associated with subtropical and temperate fruits, a total amount of 149 soil and root samples were collected from within apple, blackberry, japanese apricot, loquat, macadamia, olive, peach, pear, persimmon, quince and raspberry orchards located in the states of São Paulo and Minas Gerais, Southeastern Brazil. From this survey, a number of species belonging to eleven genera were identified, namely Aorolaimus nigeriensis, Discocriconemella degrissei, Helicotylenchus dihystera, H. erythrinae, H. microcephalus, H. pseudorobustus, Helicotylenchus spp., Hemicycliophora poranga, Meloidogyne hapla, M. incognita, M. javanica, Mesocriconema onoense, M. ornata, M. sphaerocephalum, M. xenoplax, Mesocriconema spp., Pratylenchus brachyurus, P. zeae, Rotylenchulus reniformis, Scutellonema brachyurus, Tylenchulus semipenetrans, Xiphinema brevicollum, X. elongatum, X. krugi, X. setariae, X. surinamense and Xiphinema spp. The most frequent genera were Helicotylenchus, Mesocriconema and Xiphinema, which occurred in 60.4, 54.4 and 30.2 % of the samples, respectively; the two most common species found were Helicotylenchus dihystera and Mesocriconema xenoplax, detected in 49.0 and 38.8 % of the samples, respectively. However, only Meloidogyne incognita and M. javanica could be associated with peach trees that were stunted or showed general symptoms of decline; in these cases, the rootstocks did not have genetic resistance to root-knot nematodes. The host suitability of several genotypes of the mentioned fruit species, plus guava, were evaluated in relation to Meloidogyne incognita race 2 and M. javanica under greenhouse conditions. The plants were individually inoculated with 5,000 nematode eggs and kept to grow in plastic bags for four months. Nematode reproductive rate was determined with basis on gall index, egg mass index and numbers of nematodes per root system and per gram of roots. Only the cultivar GF-677 of Prunus persica x P. dulcis was susceptible to both nematode species. All other genotypes were poor/resistant hosts, even that some allowed the parasites to reproduce at low rates. The pathogenicity of Meloidogyne incognita race 2 to persimmon cv. Kyoto was also studied under greenhouse conditions. After six months of the inoculation with increasing nematode population levels - 0; 160; 800; 4,000; 20,000; and 100,000 eggs/plant - a negative correlation with plant height and top dry weight values was obtained. As an intense root galling was associated with low nematode reproductive rates and some depressive effects on the plant growth, the reaction was rated as being of intolerance.
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Interactive effects of nemarioc-al and nemafric-bl phytonematicides on growth and foliar nutrient elements of tomato cultivar 'HTX 14' plantsMaake, Mafutha Violet January 2018 (has links)
Thesis (MSc. Agriculture (Horticulture)) -- University of Limpopo, 2018 / The production of tomato (Solanum lycopersicum L.) plants had been crucial in various
parts of the world since tomato fruit contribute widely to human health. However, most
tomato cultivars had been shown to be highly susceptible to plant-parasitic nematodes,
especially the root-knot (Meloidogyne species) nematodes. Two cucurbitacin-containing
phytonematicides, namely, Nemarioc-AL and Nemafric-BL phytonematicides,
manufactured from fruits of Cucumis species, are being researched and developed in
South Africa as an alternative for management of Meloidogyne species. Most trials on
tomato plants and cucurbitacin-containing phytonematicides had been under
greenhouse conditions, with limited information on their interactive effects under
microplot and field conditions. The objectives of this study were: (1) to determine the
interactive effects of Nemarioc-AL and Nemafric-BL phytonematicides on growth and
accumulation of nutrient elements in leaf tissues of tomato plants under microplot
conditions and (2) to investigate the interactive effects of Nemarioc-AL and Nemafric-BL
phytonematicides on growth and accumulation of nutrient elements in leaf tissues of
tomato plants under field conditions. In the microplot study, uniform four-week-old
tomato cv. 'HTX 14' seedlings were transplanted in 4 L plastic bags containing loam soil
and Hygromix-T at the 3:1 ratio (v/v). Plastic bags were inserted into holes at 0.50 m
inter-row spacing and 0.60 m intra-row spacing. The 2 x 2 factorial trial, with the first
and second factors being Nemarioc-AL and Nemafric-BL phytonematicides,
respectively, each at two levels. The four treatments, namely, AL0BL0, AL0AL1, BL0BL1
and AL1BL1, were arranged in a randomised complete block design. Treatments were
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applied seven days after transplanting and repeated weekly until harvest. Under field
conditions, uniform four-week-old tomato cv. 'HTX 14' seedlings were transplanted into
the field at 0.50 m inter-row spacing and 0.60 m intra-row spacing. Treatments,
experimental designs and application interval were as those under microplot conditions.
At 60 days after the treatments, seedlings AL × BL interaction was not significant on all
plant variables in Experiment 1 under microplot conditions, whereas in Experiment 2 the
interaction was highly significant (P ≤ 0.01) on dry shoot mass, contributing 72% in total
treatment variation (TTV) of the variable. Relative to untreated control, the two-way
matrix showed that the interaction reduced dry shoot mass by 8%. Nemarioc-AL
phytonematicide had a significant (P ≤ 0.05) effect on stem diameter in Experiment 1
under field conditions, whereas Nemafric-BL phytonematicide had significant effects on
plant height in Experiment 2, contributing 39 and 56% in TTV of the respective
variables. Relative to untreated control, Nemarioc-AL phytonematicide increased stem
diameter by 4%, whereas Nemafric-BL phytonematicide increased plant height by 2%.
The interaction was also significant (P ≤ 0.05) on Na and S and highly significant (P ≤
0.01) on Zn, contributing 76, 26 and 6%, respectively, in TTV of the respective variables
in Experiment 1 under field conditions. Using a two-way matrix, the interaction
increased Na and S by 12 and 41%, respectively, but reduced Zn by 52%. In
Experiment 2, the interaction was highly significant (P ≤ 0.01) on P alone, contributing
16% in TTV of the variable, with the interaction reducing P by 76%. Nemarioc-AL
phytonematicide had significant effects (P ≤ 0.05) on Ca and highly significant effects (P
≤ 0.01) on S, contributing 31 and 58% in TTV of the respective variables in Experiment
1. Relative to untreated control, Nemarioc-AL phytonematicide increased P by 39%. In
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Experiment 2, Nemarioc-AL phytonematicide had significant effects on Ca and highly
significant effects (P ≤ 0.01) on S, contributing 66 and 49% in TTV of the respective
variables. Relative to untreated control, Nemarioc-AL phytonematicide reduced Ca by
19% and S by 36%, respectively. Nemafric-BL phytonematicide had a significant effect
(P ≤ 0.05) on P, contributing 33% in TTV of the variable in Experiment 1. Relative to
untreated control, Nemafric-BL phytonematicide increased P by 41%. In Experiment 2,
Nemafric-BL phytonematicide had significant effects (P ≤ 0.05) on S, contributing 40%
in TTV of the variable. Relative to untreated control, Nemafric-BL phytonematicide
reduced S by 33%. At 74 days after initiating the treatments under field conditions, the
interaction of Nemarioc-AL and Nemafric-BL phytonematicides were not significant for
plant height, stem diameter, fresh fruit and dry shoot mass in both experiments.
Nemarioc-AL phytonematicide was also not significant in all plant variables in both
experiments. Effects of Nemafric-BL phytonematicide were highly significant on dry
shoot mass in Experiment 1 and stem diameter in Experiment 2, contributing 60 and
67% in TTV of the respective variables. Relative to untreated control, Nemafric-BL
phytonematicide reduced dry shoot mass by 28% and increased stem diameter by 11%
in Experiment 1 and Experiment 2, respectively. The AL × BL interaction had significant
effects (P ≤ 0.05) on P, contributing 57% in TTV of the variable in Experiment 1.
Relative to untreated control, the interaction increased P by 12%. In Experiment 2, the
interaction had significant effects (P ≤ 0.05) on K, Mg, S and Mn, contributing 78, 65, 74
and 68% in TTV of the respective variables. Using a two-way matrix, relative to
untreated control, the interaction increased K by 8%, but reduced Mg, Mn and S by 14,
82 and 1%, respectively. Nemarioc-AL phytonematicide was not significant in both the
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experiments, whereas Nemafric-BL phytonematicide had significant effects on Mg in
Experiment 1, contributing 68% in TTV of the variable. Relative to untreated control,
Nemafric-BL phytonematicide increased Mg by 15%. In conclusion, the interaction of
Nemarioc-AL and Nemafric-BL phytonematicides were not compatible with each other
as they had undesirable effects on growth of tomato plants and accumulation of most
essential nutrient elements in leaf tissues of this plant. / National Research Foundation (NRF)
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Komplexní charakteristika hlístice Phasmarhabditis hemaphrodita. / The complex characterisation of nematode Phasmarhabditis hermaphroditaNERMUŤ, Jiří January 2012 (has links)
Ph.D. thesis "The complex chacterisation of the nematode Phasmarhabditis hermpahrodita" is focused on the study of ecology of slug parasitic nematode P. hermaphrodita, its general characterisation in the context of all nowadays knowledge. The thesis consists the general introduction, that introduces the whole nowadays research of P. hermaphrodita, and four original works, that follow the introductory chapter. The first work deals with the orientation of P. hermaphrodita in 2D and 3D space and reaction on the presence of different hosts or nutritive substrates. The other study deals with the reaction of P. hermaphrodita on various animal and plant nutritive substrates and in the first place the influence of these substrates on the development of nematodes and quality and quantity of progeny. The third scope of this thesis is the influence of intraspecific competition on development, quality and quantity of nematodes and the last part of this text comprises a short study of the persistence of P. hermaphrodita in different substrates, from mineral to organic.
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Levantamento, reprodução e patogenicidade de nematóides a fruteiras de clima subtropical e temperado. / Field survey, reproduction and pathogenicity of nematodes to subtropical and temperate fruits.Carlos Eduardo Rossi 18 April 2002 (has links)
Objetivando melhor conhecimento a respeito dos nematóides encontrados associados a fruteiras de clima subtropical e temperado, coletaram-se 149 amostras de solo da rizosfera e de raízes de amoreira-preta, caquizeiro, framboeseira, macieira, marmeleiro, nespereira, nogueira-macadâmia, oliveira, pereira, pessegueiro e umezeiro em áreas de produção do Estado de São Paulo e em uma localidade de Minas Gerais. Como resultado desse levantamento, identificaram-se 11 gêneros e as espécies relacionadas a seguir: Aorolaimus nigeriensis, Discocriconemella degrissei, Helicotylenchus dihystera, H. erythrinae, H. microcephalus, H. pseudorobustus, Helicotylenchus spp., Hemicycliophora poranga, Meloidogyne hapla, M. incognita, M. javanica, Mesocriconema onoense, M. ornata, M. sphaerocephalum, M. xenoplax, Mesocriconema spp., Pratylenchus brachyurus, P. zeae, Rotylenchulus reniformis, Scutellonema brachyurus, Tylenchulus semipenetrans, Xiphinema brevicollum, X. elongatum, X. krugi, X. setariae, X. surinamense e Xiphinema spp.. Os três gêneros mais freqüentes foram Helicotylenchus, Mesocriconema e Xiphinema, presentes em 60,4; 55,0 e 30,2 % das amostras, respectivamente; as espécies mais comuns foram H. dihystera e M. xenoplax, ocorrendo em 49 e 38,3 % das amostras. Contudo, apenas M. incognita e M. javanica estavam associados a danos em pessegueiros cujos porta-enxertos não tinham resistência genética. Em casa de vegetação, avaliaram-se as reações de genótipos das citadas fruteiras, mais goiabeira, frente aos nematóides de galhas Meloidogyne incognita raça 2 e M. javanica. As plantas, individualmente inoculadas com 5000 ovos de cada espécie de nematóide, foram conduzidas em recipientes plásticos durante 120 dias. A caracterização das reações baseou-se na capacidade reprodutiva dos parasitos, determinando-se os índices de massas de ovos e de galhas, bem como os números de nematóides por sistema radicular e por grama de raízes. Apenas a cultivar GF-677 de Prunus persica x P. dulcis comportou-se como suscetível, possibilitando desenvolvimento e multiplicação dos dois nematóides. Os demais genótipos avaliados foram hospedeiros desfavoráveis ao desenvolvimento dos nematóides, sendo considerados resistentes, embora vários deles tivessem proporcionado restritas taxas de reprodução dos parasitos. Estudou-se ainda, também sob condição de casa de vegetação, a patogenicidade de M. incognita raça 2 em caquizeiro 'Kyoto', verificando-se correlação negativa entre os níveis populacionais iniciais utilizados (0, 160, 800, 4 000, 20 000 e 100 000 ovos por parcela) e a altura e a massa seca de raízes das plantas, após seis meses da inoculação. Tendo em vista que a intensa formação de galhas radiculares observada e o efeito negativo sobre os dois parâmetros de crescimento das plantas mostraram-se associados a taxas de reprodução muito baixas do parasito, considerou-se que a reação ocorrida foi de intolerância. / In order to achieve a better knowledge on the nematodes found associated with subtropical and temperate fruits, a total amount of 149 soil and root samples were collected from within apple, blackberry, japanese apricot, loquat, macadamia, olive, peach, pear, persimmon, quince and raspberry orchards located in the states of São Paulo and Minas Gerais, Southeastern Brazil. From this survey, a number of species belonging to eleven genera were identified, namely Aorolaimus nigeriensis, Discocriconemella degrissei, Helicotylenchus dihystera, H. erythrinae, H. microcephalus, H. pseudorobustus, Helicotylenchus spp., Hemicycliophora poranga, Meloidogyne hapla, M. incognita, M. javanica, Mesocriconema onoense, M. ornata, M. sphaerocephalum, M. xenoplax, Mesocriconema spp., Pratylenchus brachyurus, P. zeae, Rotylenchulus reniformis, Scutellonema brachyurus, Tylenchulus semipenetrans, Xiphinema brevicollum, X. elongatum, X. krugi, X. setariae, X. surinamense and Xiphinema spp. The most frequent genera were Helicotylenchus, Mesocriconema and Xiphinema, which occurred in 60.4, 54.4 and 30.2 % of the samples, respectively; the two most common species found were Helicotylenchus dihystera and Mesocriconema xenoplax, detected in 49.0 and 38.8 % of the samples, respectively. However, only Meloidogyne incognita and M. javanica could be associated with peach trees that were stunted or showed general symptoms of decline; in these cases, the rootstocks did not have genetic resistance to root-knot nematodes. The host suitability of several genotypes of the mentioned fruit species, plus guava, were evaluated in relation to Meloidogyne incognita race 2 and M. javanica under greenhouse conditions. The plants were individually inoculated with 5,000 nematode eggs and kept to grow in plastic bags for four months. Nematode reproductive rate was determined with basis on gall index, egg mass index and numbers of nematodes per root system and per gram of roots. Only the cultivar GF-677 of Prunus persica x P. dulcis was susceptible to both nematode species. All other genotypes were poor/resistant hosts, even that some allowed the parasites to reproduce at low rates. The pathogenicity of Meloidogyne incognita race 2 to persimmon cv. Kyoto was also studied under greenhouse conditions. After six months of the inoculation with increasing nematode population levels 0; 160; 800; 4,000; 20,000; and 100,000 eggs/plant a negative correlation with plant height and top dry weight values was obtained. As an intense root galling was associated with low nematode reproductive rates and some depressive effects on the plant growth, the reaction was rated as being of intolerance.
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Communautés de nématodes phytoparasites associés à l'olivier : réponse aux forçages anthropiques et environnementaux / Plant-parasitic nematodes communities associated to olive trees : response to anthropogenic environmental and forcingsAli, Nadine 08 October 2015 (has links)
Les interventions humaines de plus en plus fréquentes et persistantes dans les écosystèmes d'une part, et l'intensification des systèmes de cultures d'autre part qui s'accompagne pour partie de méthodes radicales pour combattre les bio-agresseurs des cultures, nous posent de multiples questions au sujet des risques écologiques liés aux changements des milieux, dont les perturbations induites sur les communautés d'organismes vivants. Les nématodes phytoparasites (NPP), vers ronds microscopiques telluriques qui occasionnent des pertes de production végétale importantes, sont partout présents en communautés. Ces nématodes répondent rapidement aux forçages extérieurs (e.g. anthropiques et environnementaux) par des modifications de la structure de leurs communautés. Par ce travail de thèse, nous cherchons à mieux comprendre l'effet des facteurs impliqués dans l'assemblage des espèces de NPP en communautés associées à l'olivier méditerranéen et à déterminer la réponse de ces communautés aux forçages imposés par la domestication de l'olivier, par l'intensification de sa culture et par différents facteurs environnementaux. L'étude a été réalisée au Maroc dans toutes les régions oléicoles (vergers traditionnels à faible densité et vergers à haute-densité), dans les zones refuge d'olivier sauvage (oléastre) et sur olivier féral. Les facteurs pédoclimatiques qui caractérisent les sites d'échantillonnage ont également été pris en considération. L'analyse de la nématofaune a révélé d'une grande diversité spécifique, de nombreuses espèces étant décrites pour la première fois sur olivier, et une nouvelle espèce (Meloidogyne spartelensis) ayant été découverte. La diversité, la composition taxonomique, trophique et fonctionnelle, la dominance des taxons, les patrons de communautés sont fortement affectés par les différents forçages pris en compte. Le gradient d'anthropisation croissante (sauvage vs féral vs cultivé traditionnel vs cultivé haute-densité) est la variable qui impacte le plus la diversité par réduction de la richesse spécifique et l'augmentation de l'abondance en NPP. L'étude a également porté une attention particulière sur la diversité des nématodes à galles des racines du genre Meloidogyne, un des principaux ravageurs de l'olivier. Elle a indiqué la dispersion de M. javanica dans les vergers et sur olivier féral, alors que d'autres espèces (M. arenaria, M. hapla et M. spartelensis) sont confinées dans les zones refuge des oléastres. Afin d'analyser la diversité génétique, des marqueurs morphologiques et moléculaires ont dévoilé d'une diversité importante entre et au sein des différentes populations de Meloidogyne. Les études diligentées dans le cadre de cette thèse confirment que la diversité et la structure des communautés de NPP pourraient être des indicateurs pertinents pour évaluer la santé des sols dans les agro et écosystèmes, en corrélant diversité et pathogénicité des communautés. Elles soulignent donc l'importance de la diversité parasitaire comme variable prioritaire à prendre en compte pour inspirer des stratégies de gestion des parasites basées sur le concept de résilience de la diversité (même s'il s'agit de parasites), pour une gestion durable des communautés de NPP et la préservation des milieux. / Human activities increasingly frequent and persistent in ecosystems on one hand, and cropping system intensification on the other hand partly with radical methods to control pests and diseases of crops, raise questions about the ecological risks related to biotop changes, including disturbances of living organism communities. Plant-parasitic nematodes (PPN), microscopic round soil-borne worms that cause significant losses of crop production, are everywhere present in communities. They respond quickly to external forces (e.g. human and environmental) by changing the structure of their communities. In this thesis, we seek to better understand the effect of the factors involved in the assemblage of PPN species in communities associated with the Mediterranean olive tree and to determine the response of these communities to forces imposed by olive domestication, by crop intensification and by various environmental factors. The study was conducted in all olive-growing regions in Morocco (traditional low density and high density orchards), in refugia areas for wild olive (oleaster) and on feral olive trees. The soil and climatic factors that characterize the sampling sites were also considered. The analysis of the nematofauna revealed a wide species diversity, many species being described for the first time on olive tree, and a new species (Meloidogyne spartelensis) have been discovered. The diversity, the species / trophic / functional structure of the communities, the dominance of the taxa, and the community patterns are strongly affected by the various forces considered. The increasing anthropogenic gradient (wild vs feral vs traditional cultivation vs high-density cultivation) is the variable that mostly impacts the diversity by reducing the species richness and increasing the abundance of PPN. A particular attention was attributed in this study to the diversity of root-knot nematodes Meloidogyne, a major pest of the olive tree. It revealed that M. javanica is widespread in orchards and olive feral, while other species (M. arenaria, M. hapla and M. spartelensis) are confined in oleaster refuge areas. In order to analyse the genetic diversity, morphological and molecular markers have revealed a significant diversity between and within different Meloidogyne populations. These thesis studies confirm that both the diversity and the structure of the PPN communities could be relevant indicators to assess soil health in agro and ecosystems, by correlating diversity and pathogenicity of communities. They therefore emphasize the importance of parasite diversity as a main variable to consider for inspiring pest control strategies based on the concept of diversity resilience (even if it concerns parasites) for sustainable management of PPN communities and for environment preservation.
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