Massal production of entomopathogenic fungi for the biological control of insects should be based on the species' nutritional and physiological characteristics and the conditions that favor high growth and sporulation. The performance of Lecanicillium lecanii on culture media with various vitamin and yeast extract concentrations was assessed. The JAB 02 and JAB 45 isolates were grown on media containing a vitamins solution (thiamin, biotin, riboflavin, pyridoxine, nicotinic acid, rho-amino benzoic acid) or other containing one vitamin at a time. The same isolates were then cultivated on media supplemented with yeast extract concentrations at 0.0, 0.5, 1.0, 2.0, 3.0 and 5.0 %. Mycelia growth was evaluated measuring two colonies diameters, every three days, during the eighteen days incubation period. Sporulation was assessed on the 18th day, by counting the conidia. The culture media containing the all-vitamins and that containing thiamin only provided greater growth of the fungus isolates but decreased JAB 45 sporulation. Nicotinic acid stimulated JAB 45 sporulation by 38.5% but did not differ (P>0.05) from the control. Little conidial production was observed for JAB 02 isolate on media containing vitamins, but an increased sporulation was observed with the addition of riboflavin, biotin and pyridoxine. Yeast extract stimulated growth of the isolates JAB 02 and JAB 45 and sporulation of JAB 02 at all concentrations but did not affect (P>0.05) conidia production by JAB 45 at any concentration. Concentration of 1.0% led to the highest sporulation values and can, therefore, be considered the most favorable since it represent one of the smaller amounts of supplement used.
biological control; entomopathogenic fungi; nutritional requirements; fungi physiology; pest control
