Optimization of a mass-rearing system to produce codling moth, Cydia pomonella, for a Sterile Insect Release programme in South Africa

[摘要] ENGLISH ABSTRACT: Codling moth, Cydia pomonella, is a worldwide pest and of major economic importanceto the South African pome fruit industry. Sterile insect release is applied as a componentof area-wide integrated pest management and includes the mass-rearing, sterilization andthe release of the sterile insects. For sterile insect release, the improvements of rearingmethods in terms of the quality of the diet ingredients and the economical aspect of therearing method are examined. The effect of genetically modified maize meal, containingthe Bacillus thuringiensis gene, in an artificial medium for codling moth rearing, isdetermined. The use of even a small amount of Bacillus thuringiensis resulted in larvalmortality and prolonged development. These results are detrimental to a mass-rearingfacility and must be considered by any rearing facility that uses genetically modifiedmaize meal if the insect is sensitive to the gene. An alternative to maize meal in theartificial medium was tested and whole wheat flour was considered to be a suitablereplacement. Agar agar is an expensive gelling agent used in the artificial medium. Analternative for agar agar (Kelcogel, Elastigel and carrageenen) is tested and the biologicaleffect on codling moth is determined. Factors such as mortality, pupal and moth weight,longevity, fecundity and development time were used as quality parameters. Resultsshowed that Elastigel was a suitable replacement for agar agar, with bigger pupae andmoths, higher fecundity and increased longevity. The economical advantage of thereplacement is a 40.91% reduction of the diet cost. The other gelling agents tested alsogave 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 largetrays placed in a ventilated box is designed. This method is more cost and space effectiveas a smaller area is needed to rear a large number of moths. The risk of dietcontamination is less because of the closed environment and more economical andeffective air handling. This is the first report of its kind to describe the mass-rearing ofcodling moth in a closed environment and the risks involved in using geneticallymodified maize meal in an artificial diet for the codling moth. These results should beincorporated into existing mass-rearing facilities or taking into consideration whendesigning new mass-rearing facilities.

[发布机构] Stellenbosch University