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Impact of insect growth regulators on non-target species, with an emphasis on Coccinellids on citrus, in Swaziland.Magagula, Cebisile N. N. 23 December 2013 (has links)
This study investigated effects of insect growth regulators (IGRs), recommended for use on
citrus in southern Africa, on non-target organisms, particularly species of Coccinellidae in and
around three citrus estates in the lowveld region of Swaziland, i.e. Tambuti, Tambankulu and
Tunzini estates. Some of the species are important predators of citrus pest insects. The
distribution of coccinellids within an agricultural land mosaic and factors affecting this
distribution pattern were also investigated. Results showed that coccinellid densities and
species diversity were lowest in the natural veld surrounding the orchards. In contrast, citrus
orchards had the highest coccinellid densities and diversity. River borders, along the Great
Usuthu river, had intermediate densities and diversity. While temperature, relative humidity and
ground insolation had no significant effect on coccinellid population densities, the presence /
absence of prey (host plant), on the other hand, was an important factor. This was the case
both for phytophagous and predatory coccinellid species. These showed close patterns of
distribution with their respective host plants or prey species. Economically important species,
such as Rodolia spp., were restricted to the orchards, while other species, especially those
whose economic role is uncertain, such as Cheilomenes lunata and Scymnus spp., were found
in most habitat types.
Coccinellid population densities were assessed during four treatment programmes: 1) an
integrated pest management (IPM) programme where no IGRs were used, 2) a programme
where any of the recommended IGRs were to be applied, 3) conventional pesticide
programme, and 4) an orchard which did not receive any chemically treatment over the last
four years (at Tambankulu estate only). Significant differences between treatment programmes
were observed at all three estates, when only economically important coccinellid species were
assessed. Orchards under an IPM programme (with no IGRs) were found to have significantly
higher population densities compared to those in IGR-treated or under a conventional pesticide
regime. The untreated orchard at Tambankulu, however, had significantly higher coccinellid
densities of economically important species and higher overall population densities than any
of the managed orchards. Of the three estates assessed, Tunzini had significantly higher
population densities of all beneficial coccinellids, (excluding the untreated orchard at Tambankulu). Natural vegetation around Tunzini and Tambuti contributed to the higher
coccinellid densities compared to Tambankulu, which was surrounded by other agricultural
land.
Laboratory and field experiments on two non-target species, the ladybird Chilocorus nigritus
(Fabricius) (all stages) and the moth Bombyx mori (Linnaeus) (larval stage) assessed specific
IGR effects, if any. Three IGRs, buprofezin, teflubenzuron (both chitin synthesis inhibitors) and
pyriproxyfen (a juvenile hormone analogue) were used. All three pesticides are currently
recommended for use on citrus in southern Africa and were tested at the recommended
dosages. Laboratory experiments showed that all three IGRs have a negative impact on both
non-target species. When B. mori received direct applications, there was larval mortality as a
result of the failing to complete moulting or dying immediately after moulting. In addition, no
larvae were able to pupate after having fed on contaminated leaves. In the case of C. nigritus,
larvae fed IGR-treated scale or sprayed with buprofezin suffered significantly higher mortality
than controls, while IGR effects on those sprayed with, or fed scale-treated with, pyriproxyfen
or teflubenzuron were not significant. No adults however, emerged from any pupae in any of
the treatment groups. All three IGRs had ovicidal activity on C.nigritus eggs. Adult fecundity
in both field and laboratory experiments was not affected significantly after exposure to any
of the three IGRs. In field experiments, the proportion of larvae of the moth and ladybird that
developed up to the reproductive adult stage, after exposure to buprofezin, was not
significantly different from the control. This was not the case for pyriproxyfen and
teflubenzuron. Buprofezin was therefore found to be the least detrimental of the three IGRs
tested.
Minimal drift was observed when a knapsack sprayer was used. However, there was spray drift
up to 32m (the furthest distance assessed here) where commercial sprayers were used. This
suggests that pesticide drift from orchards to adjacent areas would have serious implications
for biological diversity in the river borders and rivers adjacent to the estates. The sensitivity
of the non-target species to the IGRs tested needs serious consideration, as it indicates a
broader spectrum of activity for the compounds than what is promoted. Additionally, natural
control may be affected. This is because the timing of IGR applications and increasing coccinellid populations coincide, resulting in a reduced pool of coccinellid predators.
This study emphasised the importance of an appropriately heterogenous landscape to maximise
habitat availability for the coccinellids. Although the economic role of the multihabitat
coccinellid species recorded here is unknown, they nevertheless clearly contribute to citrus pest
control. Such a mosaic landscape, in conjunction with IPM, with no IGR use, promotes
ecological diversity and controls pests with minimum disruption to biodiversity. The use of
IGRs in citrus thus needs carefiil reconsideration in light of the non-target effects observed on
the two species, especially the valuable predatory species, C. nigritus. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1998.
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The establishment of a virus free laboratory colony of Cryptophlebia leucotreta (False Codling Moth) and characterisation of Cryptophlebia leucotreta Granulovirus (CrleGV) genesLudewig, Michael Hans January 2003 (has links)
Cryptophlebia leucotreta is an economically important agricultural pest throughout Sub-Saharan Africa. CrleGV has been considered as an alternative to chemical control of this pest due to its host specificity and innocuous nature towards vertebrates. A CrleGV free laboratory colony of C. leucotreta would be useful for the isolation of genotypically pure strains of the CrleGV and for virulence comparisons between isolates. It is preferable to have a full characterisation of CrleGV prior to its registration and release into the environment as a biopesticide. A laboratory colony of C. leucotreta, set up at Rhodes University, containing a low level of infection indicated that CrleGV is vertically transmitted. To establish a virus free laboratory colony of C. leucotreta, a solution of 3.5% sodium hypochlorite and 1% Tween 20 was used to surface decontaminate C. leucotreta eggs for removal of transovum CrleGV from the laboratory colony. No apparent infection by CrleGV was induced by subjecting larvae to stress. PCR of DNA extracted from larvae using CTAB failed to detect virus in the laboratory colony. This detection protocol was able to detect down to 60 fg (480 genome copies of CrleGV). The possibility of low-level virus remaining in the colony requires monitoring of genotypic purity of virus manipulated in the colony. Sequencing of Bam HI/KpnI fragments produced a preliminary sequence of the granulin region of CrleGV. This preliminary sequence supports the trend that the gene organisation of the granulin region of the granuloviruses infecting the family Tortricidae is conserved.
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Potential of selected natural products as repellents against vertebrate pests of cropsTilly Gaoh, Abdouramane. January 1999 (has links)
No description available.
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Biologiese beheer van plantparasitiese nematodes met die swam Paecilomyces lilacinus by aartappels, sitrus en wingerdNeethling, Jacob van der Westhuizen 12 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: Paecilomyces Ii/acinus, ras 251 (geregistreer in terme van wet 36 van 1947 as Suid-Afrika se eerste
natuurlike nematisiede en kommersieel beskikbaar as PI Plus) is as biologiese beheer agent getoets by
aartappels en in geïntegreerde beheer programme by sitrus en wingerd teen respektiewelik Me/oidogyne
species, Ty/enchu/us semipenetrans en verskeie ektoparasitiese nematodes. Die swam toon belofte vir
die beheer van hierdie nematodes en het terselfdertyd nie 'n nadelige effek op nie-teiken, voordelige
organismes in die grond nie. Veral in kombinasie met chemiese middels, as deel van geïntegreerde
programme, kan dit lei tot verminderde gebruik van hoogs toksiese middels en dus meer
omgewingsvriendelike landboupraktyke.
Biological control of plant parasitic nematodes on potatoes, citrus and grapevine with the
fungus, Paecilomyces liIacinus.
Paecilomyces liIacinus, race 251 (registered in terms of act 36 of 1947 as South Africa's first natural
nematicide, commercially available as PI Plus) was tested as a biological control agent on potatoes and
in integrated control programs on citrus and grapevine against Me/oidogyne species, Ty/enchu/us
semipenetrans and various ectoparasitic nematodes respectively. The fungus shows promise for the
control of these nematodes, without having a harmful effect on non-target, beneficial organisms in the
soil. Especially in combination with chemical products, as part of integrated programs, this can lead to
less use of highly toxic compounds and thus to more environmentally friendly agricultural practices. / AFRIKAANSE OPSOMMING: Sedert die ontdekking van die swam, Paeci/omyces Ii/acinus (Thom.) Samson as 'n effektiewe
eierparasiet van Meloidogyne incognita acrita en Globodera pal/ida (Jatala et al., 1979) het verdere
veldproewe in Peru tot die effektiewe beheer van M. incognita en Tylenchulus semipenetrans gelei. Na
verskeie suksesse in Peru is die swam onder verskillende klimaat- en grondkondisies in verskeie ander
lande beproef. Die sukses behaal in die Filippyne het gelei tot die kommersiële produksie van die swam
onder die handelsnaam Biocon. Anders as met chemiese middels vind die werking van biologiese
agente stadig oor tyd plaas. Biologiese beheer sal nie chemiese beheer sonder meer kan vervang nie.
Dit behoort egter deel te vorm van geïntegreerde nematode bestuur. Inkorporering van die natuurlike
organismes, die oordeelkundige gebruik van chemiese nematisiedes, moontlik in kombinasie met die
biobeheer agente, weerstand, en ander kulturele praktyke moet ernstig oorweeg word as ons hoop om
die steeds groeiende wêreldbevolking te voed (Jatala, 1986).
Paecilomyces liIacinus, ras 251, Suid-Afrika se eerste geregistreerde natuurlike nematisiede,
kommersieel beskikbaar as PI Plus, is in die Olifantsrivier besproeiingsgebied geëvalueer vir die bestuur
van ekonomies belangrike plantparasitiese nematodes by aartappels, sitrus en wingerd. Hierdie
gewasse is belangrike bedryfstakke van die streek en is onderhewig aan skade deur nematodes wat die
opbrengs nadelig beïnvloed. Chemiese beheer bied slegs 'n korttermyn oplossing vir nematode
probleme en skadelike getalle word in 'n kort tyd weer opgebou. Boonop lei dié hoogs toksiese middels
tot agteruitgang van die omgewing en sy waterbronne. Die toenemende besorgdheid hieroor en die
groot potensiaal van biologiese beheer agente (Jatala, 1986) was die hoofrede vir die werk waaroor hier
gerapporteer word.
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COMPETITIVE INTERACTIONS BETWEEN CHELONUS INSULARIS CRESSON AND TELENOMUS REMUS NIXON, TWO PARASITOIDS OF SPODOPTERA EXIGUA HUBNER.Earl, Sharon Leigh. January 1983 (has links)
No description available.
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The influence of synthetic pyrethroids on phytophagous mites and their natural enemies in apple orchardsHeunis, J. M. (Juanita Maria) 03 1900 (has links)
Thesis (MSc)--Stellenbosch University, 1992. / One copy microfiche. / ENGLISH ABSTRACT: The effects of synthetic pyrethroids on the spider mite, Tetranychus urticae Koch,
and its natural enemies was investigated. The pyrethroid cyfluthrin, sprayed for
the control of fruit weevil Phlyctinus callosus, did not cause mite outbreaks and
was not harmful to the predators when sprayed before they appeared on the
apple trees. This spray also gave good control of thrips, bollworm (Heliothis
armigera) and fruit weevil (P. callosus). A late season spray of deltamethrin
against codling moth, caused an increase in the phytophagous mite population.
This was assosiated with a temporary reduction in the population level of the
predatory beetle, Oligota fageli.
The plants found on the orchard floor were examined. The plant diversity was
low and plants that acted as hosts of phytophagous mites during the winter were
scarce. However, Solanum nigum carried high mite populations and infected the
adjacent apple trees. The plants were too few to have an effect on the whole
orchard.
Eight synthetic pyrethroids were tested for repellency in a leafdisk dip and spray
bioassay using T. urticae. Deltamethrin and fenvalerate caused no walk-off.
Cyfluthrin and fluvalinate caused moderate walk-off and bifenthrin, cyhalothrin
and lambda-cyhalothrin caused high walk-off. / AFRIKAANSE OPSOMMING: Die invloed van sintetiese piretroIedes op die rooispinmyt, Tetranychus urticae
Koch en hul natuurlike vyande is ondersoek. Die piretroIed, cyfluthrin, gespuit
vir die beheer van snuitkewer, P4ctinus callosus, het the mytuitbrake
veroorsaak the en was ook the skadelik vir predatore nadat dit vroeg in die
seisoen, voordat myte in die appelbome verskyn het, gespuit is the. Die
bespuiting het ook goeie beheer van blaaspootjies, bolwurm (Heliothis amdgera)
en P. callosus gegee. Deltametrien wat later in die seisoen toegedien is vir die
beheer van kodlingmot, Cydia pomonella, het 'n mytuitbraak veroorsaak. Dit
word geassossieer met die tydelike onderdrukking van die populasievlak van die
predatoriese kewer, Oligota fageli.
Die plante in die dekgewas is ondersoek. Die plant-verskeidenheid was laag en
plante wat kon dien as oorwinterings gashere vir fitofage myte kon dien was
skaars. Solanum nigrum het egter groot bevolkings myte gedra wat die
appelbome naaste aan hulle eerste besmet het. Daar was egter te min van
hierdie plante om 'n invloed op die hele boord te he.
Agt piretroIedes is vir afwering van T. urticae in 'n blaarskyf doop en spuit
bioessal getoets. Deltamethrin en fenvalerate het geen afwering getoon the.
Cyfluthrin en fluvalinate het 'n redelike afwering, terwyl bifenthrin, cyhalothrin
en lamda-cyhalothrin het 'n hod mate van afwering getoon
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Insect adhesion on rough surfaces and properties of insect repellent surfacesZhou, Yanmin January 2015 (has links)
No description available.
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Biological control of Tetranychus urticae Koch in hops by phytoseiid mites : feasibility, spatial aspects of interactions, and managementStrong, Willard Billings, 1959- 27 April 1995 (has links)
Graduation date: 1995
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BIONOMICS OF THE GREEN LACEWING CHRYSOPA CARNEA STEPHENS (CHRYSOPIDAE: NEUROPTERA) IN ARIZONAMalik, Mohamed Yousif, 1935- January 1981 (has links)
Chrysopa carnea Stephens is widely distributed throughout the world. The larva is a potential control agent of pests in greenhouses, field crops and orchards. Its use as a biocontrol agent in integrated control is enhanced by its tolerance to some insecticides. Because of its considerable usefulness, studies to investigate the bionomics of this predator under both laboratory and field conditions were initiated. The study of population dynamics in alfalfa fields indicated that the major factors which govern the fluctuation of Chrysopa are: climate, food (e.g. aphids), diseases, parasites and agricultural practices (e.g. cutting of alfalfa hay). In each year and for each field, it was apparent that population levels of larvae rose to peaks five to six times; this suggests that there are five to six generations per year. The study of the effect of temperature and photoperiod on development in the laboratory showed that the egg, larva and pupa responded significantly to both temperature and photoperiod and an interaction between these two parameters was detected. Relative to fecundity and longevity, the investigations revealed that there was a photoperiod response only with respect to number of eggs laid and preoviposition period and that interaction between temperature and photoperiod was absent. In the case of the oviposition period, a response to temperature was detected and interaction between temperature and photoperiod existed. The different regimes had no significant effect on longevity of either sex. Consumption of prey differed significantly--being highest with beet armyworm eggs (Spodoptera exigua (Hubner) followed by corn earworm (Heliothis zea (Boddie) and tobacco budworm (Heliothis virescens (Fabricius). Fewer pea aphids (Acyrthosiphon pisum (Harris) were consumed than any of the lepidoterous eggs. Resistance to starvation differed significantly among the three instars; the newly-emerged Chyrsopa larvae had the shortest survival period. Studies on consumption of different instars of tobacco budworm by different instars of the predator indicated that the first instar was most vulnerable to attack by each of the first and third instars of the predator. Experiments were conducted to determine the effects of cold storage (4.4°C) of eggs and pupal cocoons for different periods of time. The results indicated that percent egg hatch and survival of emerging larvae were highest when stored for one week. Pupal storage for different periods had no detrimental effect on survival of pupae nor fecundity of emerging adults.
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Effect of Bacillus thuringiensis var. thuringiensis Berliner on the pink bollworm, Pectinophora gossypiella (Saunders)Graves, Garth Norman, 1941- January 1970 (has links)
No description available.
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