Comparison of survival and pathogenicity of Beauveria bassiana A1-1 spores produced in solid and liquid state fermentation on whitefly nymph, Trialeurodes vaporariorum

Abstract

In order to use entomopathogenic fungi (EPF) as biological control agents, it is necessary to mass produce the EPF in an economical and cost-effective manner. Currently, the mass production of EPF is carried out mainly in two ways: solid-state fermentation in which the aerial conidia are produced, and liquid fermentation in which the blastospores and submerged conidia are produced. This research compares the survival of Beauveria bassiana A1-1spores from solid and liquid culture media, after 0, 3, 6 and 9 months of storage at room temperature (25 ± 5°C) and in the refrigerator (4°C). Furthermore, it compares the pathogenicity of spores immediately after production and after 9 months of storage on third nymphs of greenhouse whitefly, Trialeurodes vaporariorum. The aerial conidia and blastospores were slightly more virulent than the submerged conidia on whitefly nymphs. In laboratory bioassays, blastospores indicated more pathogenicity on nymphs than submerged conidia, even though there was no significant difference in the pathogenicity of the spores produced in liquid culture media in greenhouse bioassays. Moreover, survival of the aerial conidia at a low temperature (4°C) was higher than that kept at room temperature (25 ± 5°C). This storage temperature comparison revealed a positive effect on the stability and survival of blastospores and submerged conidia as well. Meanwhile, the survival of spores drastically decreased after 3 months of storage at room temperature.

Keywords

• beauveria bassiana
• entomopathogenic fungi
• greenhouse whitefly
• pathogenicity
• survival rate