Bioassays with Isolates of Entomopathogenic Fungi against Ephestia kuhniella Zell. (Lepidoptera: Pyralidae)

S. DRAGANOVA1 and E. MARKOVA2
1 Plant Protection Institute, BG - 2230 Kostinbrod, Bulgaria
2 Biological faculty, Sofia University “St. Kliment Ohridski”, BG - 1164 Sofia, Bulgaria

Abstract

DRAGANOVA, S. and E. MARKOVA, 2006. Bioassays with isolates of Entomopathogenic fungi against Ephestia kuhniella Zell. (Lepidoptera: Pyralidae). Bulg. J. Agric. Sci., 12: 637-643

Bioassays with conidial suspensions of isolates of the entomopathogenic fungi - four of Beauveria bassiana (Bals.) Vuill., two of Metarhizium anisopliae (Metsch.) Sorok., one of Verticillium lecanii (Zimm.) Viegas have been proved against larvae of Ephestia kuhniella Zeller (Lepidoptera: Pyralidae). Lethal effect of each fungal isolate was estimated by values of the cumulative mortality (%) in treated populations during 8 days. Virulence of each fungal isolate was estimated by values of the median lethal time (LT50), calculated by probit analysis. It has been established that the isolate 383Bb of B. bassiana caused the highest lethal effect to larvae - 87.78% ± 13.18, following by isolates 399Bb and 382Bb of B. bassiana - 60.00% ± 8.14 and 58.89% ± 8.75, respectively. Isolates 15Ma and 31Ma of M. anisopliae and the isolate 32Vl of V. lecanii showed less lethal effect in comparison with the other tested isolates. It has been established that only one isolate (383Bb of B. bassiana) was with efficacy over 70% to larvae of E. kuhniella. The isolate 383Bb of B. bassiana was with the highest virulence. It’s values of the median lethal time varied within a narrow confidence interval from 4.811 to 5.234 days (at p-level < 0.05), with the average value of LT50 5.019 days.

Key words: entomopathogenic fungi, Beauveria bassiana, Metarhizium anisopliae, Verticillium lecanii, Ephestia kuhniella, virulence