Evaluation of factors affecting the mass production of the entomopathogenic fungus Verticillium lecanii

Microbial control has been considered a significant tool in integrated pest management and is a favorable ecological strategycompared to chemical control. Many isolates of Verticillium lecanii demonstrated high pathogenicity to aphids and other insect pests. Themass production of a successful microbial biocontrol agent should be optimized to produce high quantities of conidia. This investigation was conducted to evaluate the effect of media type, temperature, and incubation period on the productivity of Verticillium lecanii (Zimm)Viegas conidia. Among the four media tested, the V. lecanii AUMC4927 strain exhibited the highest conidial production (9.36x107 conidia/ml) on Sabouraud's media. Czapek’s medium supported maximum sporulation at 7.56x107 conidia/ml whereas the potato dextrose and malt extract media produced 4.92x107 conidia/ml and 2.74x107 conidia/ml, respectively. There were significant differences in conidial production among the different temperatures tested. The highest conidial production was recorded at 25oC after 28-days of incubation. However, the lowest productivity was detected at 20oC on the four media types. The optimum incubation period ranged between the third and fourth week depending on the temperature degree and media type. Data showed that Sabouraud’s medium at 25oC for four weeks seems to be favorable for the highest conidial production (4.50x108)conidia/ml) by the entomopathogenic fungus V.lecanii.