Tetramycin B3: An Effective and Biological Nematicide for Bursaphelenchus xylophilus

Pine wilt disease, caused by Bursaphelenchus xylophilus (Steiner & Buhrer, 1934) Nickle 1981, poses a significant threat to the safety of pine forests in the world. Currently, the available nematicides for controlling this disease are limited. Finding new nematicides is crucial for the effective prevention and control of pine wilt disease. In this study, we discovered that tetramycin B3, derived from Streptomyces ahygroscopicus, demonstrated a promising effect on pine wilt disease. The LC50 values of tetramycin B3 at 24, 48, and 72 h were 26.49, 23.37, and 12.79 μg/mL, respectively. Tetramycin B3 significantly inhibited the feeding and growth rate of B. xylophilus at low concentrations while also increasing ROS (reactive oxygen species) production and lipid accumulation. Furthermore, tetramycin B3 markedly inhibited the activity of detoxifying and protective enzymes. Transcriptome and metabolome analyses indicated that tetramycin B3 significantly affected the expression of genes related to lysosomes, autophagy, and lipid metabolism in B. xylophilus. Additionally, tetramycin B3 delayed the onset of pine wilt disease. Transcriptome results showed that tetramycin B3 significantly influenced the expression of genes related to defense responses in pine trees and induced pine trees to produce disease-resistant mechanisms. Future research will focus on further elucidating the mechanism of action of tetramycin B3 against B. xylophilus and verifying the gene functions identified through transcriptome screening.