Investigation on the effect of three medicinal plant essential oils on mycelia growth, conidia production and germination of three species of entomopathogenic fungi in laboratory conditions

Due to healthy and environmental hazards of chemical pesticides, it is important to change the methods in durable and Organic agriculture by using bio pesticides and essential oils. The effects of essential oils of three aromatic plants, Mentha spicata, Cuminum cyminum and Citrus aurantifolia was studied on mycelial growth, germination and conidial production rate of three entomopathogenic fungi Lecanicillium longisporum, Beauveria bassiana and Metarhizium anisopliae. This study was done in a completely randomized design with five treatments (five concentrations of essential oils) and three replicates on SDA medium in 27±1°C. Results showed that L. longisporum and B. bassianawere the most susceptible with 41.06% colony growth prevention and M. anisopliae was the most resistant to the essential oils. Also the essential oil of C. cyminum with 41.06% had the most effect and C. aurantifolia with 20.44% had the least effect on mycelial growth. In concentration of 20 μl, the essential oils of C. cyminum and C. aurantifolia showed the most and the least preventive effect in conidial germination, respectively.