Open AccessEffect of nutrition on growth and virulence of the entomopathogenic fungus Beauveria bassiana
Author(s) -
Safavi S. A.,
Shah Farooq A.,
Pakdel Aziz K.,
Reza Rasoulian G.,
Bandani Ali R.,
Butt Tariq M.
Publication year - 2007
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2007.00666.x
Subject(s) - conidium , beauveria bassiana , virulence , biology , metarhizium anisopliae , germination , entomopathogenic fungus , microbiology and biotechnology , bassiana , spore , metarhizium , hypocreales , beauveria , biological pest control , botany , horticulture , ascomycota , gene , biochemistry
Three isolates of the entomopathogen Beauveria bassiana along with one strain of Metarhizium anisopliae were cultured on seven media with different carbon/nitrogen (C/N) ratios. The effect of nutrition on virulence of the isolates was evaluated via measurement of colony growth, spore yield, germination speed, conidial C/N ratio and Pr1 (a serine protease) activity. ‘Osmotic stress’ medium produced the lowest colony growth with low numbers of conidia in all isolates. However, these conidia showed a high germination rate and virulence. However, conidial Pr1 activity was low in some isolates. In most but not in all cases conidia from 1% yeast extract, 2% peptone and low (10 : 1) C/N medium had higher Pr1 activity compared with conidia from other media. However, in some instances we could not conclude that there was a relationship among germination rate, conidial Pr1 activity and virulence. C/N ratio of conidia was statistically different among various media and fungal isolates. Conidia with lower C/N ratio generally produced lower LT 50 (lowest median lethal time) values (more virulent). Insect‐passaged conidia from different media had lower C/N ratio compared with similar conidia from artificial cultures. Therefore, they should be more virulent than in vitro produced conidia. As germination rate, conidial Pr1 activity and C/N ratio are independent of host, it seems that host‐related determinants such as insect cuticle and physiology and environmental conditions may influence host susceptibility and therefore fungal isolate virulence towards host insects.