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
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/69805 |
| Date | 03 1900 |
| Creators | Heunis, J. M. (Juanita Maria) |
| Contributors | Pringle, K. L., Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 68 p. : ill. |
| Rights | Stellenbosch University |
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