Prokaryotically expressed Buthus martensii Karsch insect depressant toxin has insecticidal effects.

An insect depressant toxin Buthus martensii Karsch insect toxin 4 (BmK IT4) cDNA was cloned into the prokaryotic expression vector pSW202 and expressed in HB101 host cells. The authenticity of this in vitro expressed peptide was confirmed by Western blotting, mass spectrometry and N-terminal peptide sequencing. Bioassays using growth media supplemented with BmK IT4 demonstrated that, at the end of the 5-day experimental period, about 77% of the testing cotton bollworm larvae were killed. Furthermore, the average weight picked up by larvae grown on BmK IT4 containing media amounts only to 0.7% of that of control group. Our results indicate that BmK IT4 may be used for biological control of insect damages in place of other traditional insecticides.