Production of Akanthomyces lecanii by submerged fermentation to control Tetranychus urticae (Acari: Tetranychidae) in Gerbera jamesonii crops

Abstract

ABSTRACT In Colombia, the Tetranychus urticae mite (Acari: Tetranychidae) is one of the most challenging phytosanitary issues faced by flower cultivators. The control of this mite has been commonly done through the use of chemical insecticides. But the mites have generated resistance to these substances over time, making their handling more difficult. Some sustainable alternatives based on the use of biological control agents (BCA) can also be implemented in the control of T. urticae. The fungus Akanthomyces lecanii has proved to be effective in the control of T. urticae, however, is conventionally produced by solid-state fermentation (SSF) with low yields and high costs. Submerged fermentation (SmF) is a successful alternative that increases yields and reduces times in BCA production. In this research, the conditions for the production of A. lecanii by SmF were determined to improve the control of T. urticae in the Gerbera jamesonii. The percentage of immobile T. urticae adults, and the median lethal time (LT50) values, were evaluated. Also, some low molecular weight compounds were extracted and detected by liquid chromatography coupled with high-resolution mass spectrometry. The concentration of A. lecanii produced in SmF was 132 times higher than that obtained from SSF and, better control of mite populations was observed both in vitro and in the field. These results show that the production of A. lecanii by SmF can be a more efficient alternative to implement comprehensive control strategies in flower crops.