Pathogenicity of a Philippine entomopathogenic fungal isolate Metarhizium flavoviridae IPLB-2 to the sweet sorghum stalk borer, Ostrinia furnacalis (Guenne)

Issue Date

10-2013

Abstract

An entomopathogenic fungal (EPF) isolate Metarhizium flavoviride-IPLB-2 (IPBL-2), originally isolated from a field-collected corn earworm. Helicoverpa armigera, was tested for pathogenicity against the sweet sorghum stalk borer, Ostrinia furnacalis. Preliminary bioassay studies revealed that this EPF could cause latent infection in O. furnacalis, which was accompanied by cessation of feeding and mummification of the cadaver. However, larval death, mycelial growth and sporulation of IPLB-2 occurred at 14, 21, and 35 days post infection (DPI), respectively. Conidia from the first passage in O. furnacalis were mass produced in potato dextrose agar and were used as inoculum in the subsequent studies. Bioassay studies using dipping method revealed that at 14 DPI, theLC50 and LC90 values of IPBL-2 to 7-day old larvae of O. furnacalis were 4.16 x 108 and 1.14 x 1014 conidia/ml, respectively . Larval death was observed earlier in O. furnacalis infected with IPLB-2 conidia from the first passage, indicating an improved virulence of IPLB-2 to O. furnacalis. Sporulation of the fungal isolate was observed at the thoracic and abdominal regions, suggesting that the mode of infection of IPLB-2 for stalk borer may be through ingestion and not the usual route which is through the cuticle. Further passage of this EPF in O. furnacalis id therefore recommended to develop a more virulent IPLB-2 strain against this insect pest.

Source or Periodical Title

The Philippine Entomologist

ISSN

0048-3753

Volume

27

Issue

2

Page

205-206

Document Type

Article

Frequency

semi-annually

Language

English

En – AGROVOC descriptors

OSTRINIA FURNACALIS; SORGHUM BICOLOR; METAZHIZIUM; ENTOMOGENOUS FUNGI; PESTS OF PLANTS; PATHOGENICITY; BIOLOGICAL CONTROL AGENTS; PHILIPPINES

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