Isolation of Macrolactin A from a new Bacillus amyloliquefaciens and its aphicidal activity against Rhopalosiphum padi.

BACKGROUND

Rhopalosiphum padi is a major infection affecting cereal crops in the boundary area. However, continuous use of chemical pesticides has increased cases of drug resistance in its field population. Therefore, we aimed to verify the insecticidal properties of Bacillus amyloliquefaciens YJNbs21.10 against aphids, isolated to determine the bioactivity of its metabolite Macrolactin A against aphids for the first time.

RESULTS

The results of activity tracking showed that the fermentation broth of YJNbs21.10 had the best inhibitory efficacy against R. padi, and the corrected efficiency reached 95.57% after 24 h. With the continuous separation and test, the efficiency of the active components decreased: Macrolactin A, as the most active substance, had a control activity against aphids under 500 mg L-1 of 74.64% at 72 h, (which was significantly lower than that of fermentation broth, indicating a synergistic effect between the active substances of each part of the strain. In addition, the result of the stereomicroscope showed that Macrolactin A damaged the body wall of aphids. The toxicity of Macrolactin A to R. padi was confirmed through the gradient test.

CONCLUSION

In this study, Bacillus amyloliquefaciens YJNbs21.10 exhibited comparable inhibitory ability to chemical pesticides suggesting its potential to provide effective biological control on aphids. The biological activity of Macrolactin A against aphids was also verified for the first time, in this experiment, the EC50 of this substance against aphids was 169.02 mg L-1 (24 h), which provided strong evidence that YJNbs21.10 may act as an effective agent for the prevention of aphid. © 2024 Society of Chemical Industry.