Isolation and culture of Entomophthora gammae, a fungal parasite of noctuid larvae [Pseudoplusia includens, biological control]

• Published in: The Florida entomologist 1984-06, Vol.67 (2), p.245-250
• Main Authors: Lin, J.S, Harper, J.D
• Format: Article
• Language: English
• Subjects: biological control; Conidia; Egg yolk; Entomophthora; Entomophthora gammae; Fungi; Germination; Humidity; Insect larvae; Noctuidae; pathogens; Pseudoplusia includens; Soybeans; Wolves; Yeast extract
• ISSN: 0015-4040; 1938-5102
• DOI: 10.2307/3493944

Entomophthora gammae (Weiser) was isolated by allowing conidia from infected soybean looper, Pseudoplusia includens (Walker), larvae to shower onto egg yolk agar. Fungal and bacterial contaminants were always present, but at 20°C, E. gammae grew fast enough to allow the subculture of hyphal bodies to clean medium. Once isolated, the fungus was cultured on Czapek solution agar, potato dextrose agar, Sabouraud dextrose agar, and Sabouraud maltose agar, all containing 0.2% yeast extract, and on Grace's insect tissue culture medium. It did not grow on Wolf's medium, potato agar or potato dextrose agar without yeast extract. The fungus grew most rapidly in culture when maintained at 25°C and 100% RH. Conidia on glass slides held at 25°C germinated only at 100% RH. A gradual increase in conidium size occurred over a 10-month period of continuous culture. Attempts to infect larvae with the cultured fungus were unsuccessful. /// Entomophthora gammae (Weiser) fué aislado permitiendo que las conidias provenientes de las larvas del medidor de la soya, Pseudoplusia includens (Walker) se dispersaran sobre agar de la yema de huevo de gallina. Hongos y bacterias contaminantes estuvieron siempre presentes, pero a 20°C, E. gammae creció lo suficientemente rápido para permitir la subcultura de cuerpos hifales para clarificar el medio. Una vez aislado, el hongo fué cultivado en una solución de agar Czapek, papa dextrosa agar, Sabouraud dextrosa agar y Sabouraud maltosa agar, todos los medios contenían 0.2% de extracto de levadura y sobre el medio Grace para cultivo de tejidos de insectos. No hubieron crecimientos sobre el medio Wolf, papa agar o papa dextrosa agar cuando no se agregó extracto de levadura. El crecimiento máximo y la germinación de las esporas ocurrió a los 25°C y con un 100% de humedad relativa. Un incremento gradual del tamaño de las conidias ocurrió durante los 10 meses de cultivos contínuos. Intentos para infestar larvas con el hongo cultivado no tuvieron éxito.