Alginate and Cornstarch Mycelial Formulations of Entomopathogenic Fungi, Beauveria bassiana and Metarhizium anisopliae

Abstract

Dry mycelium of the entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana in alginate and cornstarch formulations was evaluated for survival of the formulated mycelium, conidial production on mycelium after exposure to artificial solar radiation, and infectivity to southern corn root worm adults, Diabrotica undecimpunctata howardi Barber. Alginate formulations were prepared with 1% sodium alginate and calcium chloride. Cornstarch formulations were prepared with gelatinized cornstarch and moist mycelium from liquid culture medium. Oil was added to some starch preparations. Results showed that cornstarch and cornstarch-oil formulations produced more conidia per gram of incorporated mycelium than other preparations. In general, alginate formulations were less productive than pure mycelium. Cornstarch and cornstarch-oil formulations were best at preserving fungi at room temperature (22°C) , whereas all formulations provided similar preservation at 4°C. Alginate formulations prevented degradation of fungi by artificial solar radiation, whereas cornstarch-oil was less effective than pure mycelium preparations. Mortality to D. undecimpunctata caused by mycelium formulated into alginate and cornstarchoil preparations were comparable to that caused by pure mycelium preparations. A lag time of 3-4 d preceded disease development on test insects, because of the need for dry mycelium to produce conidia before initiating infection.