Tropentag, October 7 - 9, 2008 in Hohenheim "Competition for Resources in a Changing World: New Drive for Rural Development"

Selection of Entomopathogenic Fungi for Spodoptera litura Control

Chiang Mai University, Department of Entomology, Thailand

Abstract

Biological control with pathogenic fungi is a promising alternative to chemical control against the insect pest of vegetable. Ten isolates of green muscardine fungus, Metarhizium anisopliae as entomopathogenic fungus were used to test for pathogenicity on second instar of common cutworm, Spodoptera litura under the laboratory conditions. The tested larvae were placed in Petri dishes containing green muscardine fungus and they were allowed to make a direct contact with the particular entomogenous fungus. It was revealed that 3 isolates of green muscardine fungus, BCC1858, BCC4849 and Khon Kaen were effectively killed 100% of the cutworm larvae within 2 days. Subsequently, M. anisopliae isolates were brought to examine with 8 different media for physiological properties. The result showed that mungbean agar (MU) was the best for mycelial growth and sporulation. Moreover, the optimum temperature for growth was ranged around 30-35°C. When the isolates were kept in the room with 12 hours light alternated with 12 hours dark, they were produced more green spores than the other. [The best conditions for sporulation were observed when the isolates were kept at 30-35°C with 12 hours light alternated with 12 hours dark.] When the 3 most effective isolates were tested with the 1^st, 2nd and 3rd instars of cutworm at 4 concentration levels included of 107, 108,109 and 1010 spores/ml. The result indicated that the isolate 4849 with the concentration of 6×108 spores/ml was the most effective one. It was observed to cease the 3rd instar of cutworm by 79.49% within 7 days.

Keywords: Spodoptera litura, Biological control, Entomopathogenic fungi, metarhizium anisopliae

Contact Address: Patcharin Krutmuang, Chiang Mai University, Department of Entomology, 50200 Chiang Mai, Thailand, e-mail: p-charinchiangmai.ac.th