INTRA-SPECIFIC VARIABILITY AMONG METARHIZIUM ANISOPLIAE STRAINS IN THEIR ABILITY TO PRODUCE BLASTOSPORES IN LIQUID CULTURE MEDIA

Abstract

This study describes intra specific variability among Metarhizium ansiopliae strains in terms of their ability to produce blastospores in selected liquid culture media. Blastospore production of 10 strains was evaluated in 6 different media representing different carbon and nitrogen sources. Irrespective of strain, media containing corn steep and yeast extract provided highest blastospore yield. Among different strains F10, ERL607, ARSEF 3297 and ARSEF 4556 produced significantly (p<0.001) higher number of blastospores at 48 hours post inoculation (hpi). At 72 hpi, blastospore concentration was significantly higher for strains ARSEF 3297, CA1, F10, CA 22 and ARSEF 4556, while the strains, V275, UWS-2 and PW produced significantly lower number of blastospores. The single highest average production (1.43x108 ± 1x107 ) was noticed in Adamek’s modified medium(AMM) in case of CA1 at 72 hpi. Media influenced the morphology and budding pattern e.g. In Adamek’s media (AM), blastospores were slender in shape and were observed frequently on apical as well as on lateral buds, whereas BH medium yielded blastospores which resembled aerial conidia. Blastospores produced on different media varied non-significantly among themselves as well as with aerial conidia in their virulence towards Tenebrio molitor. Considering the intra specific variability in blastospore production, this study highlights the importance of screening strains for their ability to produce blastospores prior to optimizing media and culture conditions for blastospore production.