Prodigiosin, a promising biocontrol agent against Thaumetopoea wilkinsoni (Tams, 1926) (Lepidoptera: Notodontidae)

Serratia marcescens Bizio (Enterobacteriaceae: Serratia) is an entomopathogenic bacterium that produces hydrolytic enzymes and toxins. It also produces a pigment with various biological properties called prodigiosin. The study was conducted at Bilecik Seyh Edebali University in 2023. In this study, the effects of medium, incubation temperature and time on the process of prodigiosin production by S. marcescens strain Se9 and the extraction efficiency of different solvents were optimized for the first time using the orthogonal Taguchi array design. The optimal yield of pigment was achieved by methanol extraction from bacteria grown in tyriptic soy broth medium at 30ºC for 96 hours. The yield of prodigiosin pigment was 83.4±1.7 mg/L in the validation experiment conducted under the optimum conditions determined. The insecticidal potential of pigment against the larvae of Thaumetopoea wilkinsoni (Tams, 1926) (Lepidoptera, Notodontidae) was demonstrated for the first time. While the mortality rate in larvae exposed to 1000 ppm of the pigment was only 40%, it was observed that doubling the applied concentration led to a significant increase in larval mortality, reaching 91%. The LC50 value of the pigment for the fourth larval stage of T. wilkinsoni was determined to be 1192 ppm. The study showed that the pigment prodigiosin may be a promising biocontrol agent for the control of T. wilkinsoni.