Chitin-amended media: Improving efficacy of Cordyceps fumosorosea as a control agent of Cydia pomonella.

The microbial control of insect pests such as the codling moth Cydia pomonella is a major challenge in the apple industry. This study investigates the potential of chitin-amended media to improve the efficacy of the entomopathogenic fungus Cordyceps fumosorosea strain JKI-BI-1496 for control of C. pomonella. Chitin, a key component of insect exoskeletons, colloidal chitin (CC) or chitosan were added in two concentrations to the liquid growth media. Only by the amendment of 0.5 % chitosan significant higher numbers of spores were formed whereas the highest biomass was achieved by amendment of chitin. Spores produced in chitosan had no significant effect on the mortality of C. pomonella. But media containing 1 % colloidal chitin (CC) significantly enhanced the efficacy of C. fumosorosea. To achieve 75 % mortality only 1.6 × 10 submerged spores/mL were needed in comparison of over four times higher concentrations in media without CC or chitin. However, while 1 % CC positively impacted spore viability during the freeze-drying formulation process, it had a detrimental effect on the fungus's resilience under prolonged sunlight exposure. These findings provide valuable insights into optimizing media and formulations to enhance the effectiveness of C. fumosorosea in biological control, particularly by improving spore production and formulation processes.