Utilization of carbohydrates by Beauveria bassiana isolates obtained from forest pests

Abstract

Carbohydrate utilization profiles of ten isolates of the entomopathogenic fungus Beauveria bassiana (Bals.-Criv.) Vuillemin were studied and compared to assist in determining their phenotypic characterization. Isolates were obtained in pure cultures from dead individuals of several forest pests collected from different regions in Bulgaria. Studies on utilization profiles were based on the acidification of twenty carbohydrates.The results indicate that sucrose, maltose and trehalose were assimilated at a high degree compared to esculin, arabinose and dulcitol. According to the results of a cluster analysis of the carbohydrate utilization profiles, the B. bassiana isolates were divided into two larger groupings. All isolates in the first larger cluster were obtained from the coleopteran insects - Stenomax aeneus, Ips typographus, I. sexdentatus and Dryocoetes autographus. Isolates from the other cluster were obtained from the lepidopteran larvae of Thaumetopoea pityocampa and Lymantria dispar, and from an adult of the coleopteran species Hylurgops palliatus. We determined that each B. bassiana isolate exhibited a different and specific carbohydrate utilization profile but differences at the p-level < 0.05 were significant among some of them. The most distinguishable was the isolate 560Bb obtained from T. pityocampa. Differences between the isolate 560Bb and the other nine B. bassiana isolates were highly significant at the p-level < 0.005. Isolate 433Bb obtained from a dead adult of I. typographus was significantly different from five of the studied isolates at the p-level < 0.05.