Thesis (PhD (Conservation Ecology and Entomology))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: Codling moth, Cydia pomonella, is a worldwide pest and of major economic importance
to the South African pome fruit industry. Sterile insect release is applied as a component
of area-wide integrated pest management and includes the mass-rearing, sterilization and
the release of the sterile insects. For sterile insect release, the improvements of rearing
methods in terms of the quality of the diet ingredients and the economical aspect of the
rearing method are examined. The effect of genetically modified maize meal, containing
the Bacillus thuringiensis gene, in an artificial medium for codling moth rearing, is
determined. The use of even a small amount of Bacillus thuringiensis resulted in larval
mortality and prolonged development. These results are detrimental to a mass-rearing
facility and must be considered by any rearing facility that uses genetically modified
maize meal if the insect is sensitive to the gene. An alternative to maize meal in the
artificial medium was tested and whole wheat flour was considered to be a suitable
replacement. Agar agar is an expensive gelling agent used in the artificial medium. An
alternative for agar agar (Kelcogel, Elastigel and carrageenen) is tested and the biological
effect on codling moth is determined. Factors such as mortality, pupal and moth weight,
longevity, fecundity and development time were used as quality parameters. Results
showed that Elastigel was a suitable replacement for agar agar, with bigger pupae and
moths, higher fecundity and increased longevity. The economical advantage of the
replacement is a 40.91% reduction of the diet cost. The other gelling agents tested also
gave acceptable results and can be considered if shortages of agar agar or Elastigel occur.
A new method of mass-rearing codling moth larvae in a closed rearing system using large
trays placed in a ventilated box is designed. This method is more cost and space effective
as a smaller area is needed to rear a large number of moths. The risk of diet
contamination is less because of the closed environment and more economical and
effective air handling. This is the first report of its kind to describe the mass-rearing of
codling moth in a closed environment and the risks involved in using genetically
modified maize meal in an artificial diet for the codling moth. These results should be
incorporated into existing mass-rearing facilities or taking into consideration when
designing new mass-rearing facilities. / AFRIKAANSE OPSOMMING: Die kodlingmot, Cydia pomonella, is van ekonomiese belang vir die Suid-Afrikaanse
kernvrugte bedryf. Die steriele insek tegniek word gebruik as ‘n komponent in area-wye
geïntegreerde plaagbeheer en sluit in die massa-aanteel, sterilisering en vrylaat van
steriele insekte. Vir die steriele insek tegniek is die verbetering van die massa-aanteel
van die kodlingmot in terme van kwaliteit van die dieet en die ekonomiese aspek van die
aanteel metode ondersoek. Die effek van genetiese gemanipuleerde mieliemeel wat die
Bacillus thuringiensis geen bevat, in ‘n kunsmatige voedselmedium vir die aanteel van
kodlingmot, is bepaal. Daar is gevind dat die gebruik van selfs ‘n klein persentasie
Bacillus thuringiensis in die mieliemeel, mortaliteit en ‘n verlengde lewenssiklus in
kodlingmot veroorsaak. Die gevolge is nadelig vir ‘n massa-aanteel fasiliteit en behoort
in ag geneem te word vir enige insek wat op ‘n kunsmatige medium, wat mieliemeel
bevat, geteel word, mits die insek sensitief is vir Bacillus thuringiensis. ‘n Alternatiewe
bestanddeel vir mieliemeel, volkoringmeel, word aanbeveel. Agar agar is ‘n duur
verdikkingsagent wat in kunsmatige mediums gebruik word. ‘n Alternatief vir agar agar
(Kelcogel, Elastigel en carrageenen) is getoets en die biologiese effek op die kodlingmot
is bepaal. Faktore soos mortaliteit, papie en mot gewig, langlewendheid, vrugbaarheid en
lengte van lewenssiklus was gebruik as kwaliteit parameters. Resultate het getoon dat
Elastigel ‘n geskikte plaasvevanger is van agar agar, met groter papies en motte, groter
vrugbaarheid en langlewendheid. Die ekonomiese gevolg van die plaasvervanger, is ‘n
vermindering van 40.91% van die dieetkoste. Die ander verdikkingagente wat is getoets
is, het aanvaarbare resultate gelewer wat noodsaaklik is indien daar ‘n tekort van
Elastigel of agar agar ontwikkel. ‘n Nuwe metode van massa-aanteel van kodlingmot
larwes is bepaal. Die metode behels ‘n geslote sisteem, waar groter aanteel bakke in ‘n
geslote, geventileerde boks geplaas word. Die metode is koste en spasie effektief en ‘n
kleiner area word benodig om ‘n groter aantal motte te lewer. Die risiko van
kontaminasie van die dieet word verminder as gevolg van die geslote sisteem wat gebruik
word en meer ekonomiese en effektiewe lugversorging word gebruik. Hierdie is die
eerste verslag van sy soort wat die massa-aanteel van kodlingmot in ‘n geslote sisteem
beskryf en wat die risiko aandui van geneties gemanipuleerde mieliemeel in ‘n
kunsmatige medium vir die kodlingmot. Hierdie resultate behoort in ag geneem te word vir reeds bestaande massa-aanteel fasiliteite of met die ontwerp van nuwe massa-aanteel
fasiliteite.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/6658 |
| Date | 03 1900 |
| Creators | Stenekamp, Daleen |
| Contributors | Addison, P., Addison, M. F., University of Stellenbosch. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 125 p. : ill. |
| Rights | University of Stellenbosch |
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