Optimisation of the production and handling of codling moths in a sterile insect release programme

Codling moth, Cydia pomonella, is 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.  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.  A new method of mass-rearing codling moth larvae in a closed rearing system using large trays placed in a ventilated box is designed.  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.