An Extensive Study on the Toxic Effects of Bacillus Thurigiensis Toxins

7. Summary

An extensive study was conducted to assess the toxic effects of Bacillus thurigiensis   toxins Btk (Dipel)   on survival, biochemical constituents and histologcal alternations in the larvae, O.rhinoceros.

  1) The larvae, O.rhinoceros exposed to sublethal concentrations of Btk (Dipel)   showed that the survival rate decresed not only with increasing concentrations of the selected Bacillus thurigiensis toxins but also with exposure time. The 96hrs LC50 values were 25µl/ml, 30µl/ml,35µ/ml,40µl/ml,45µl/ml in III instar larvae treated with Btk (Dipel) biocide.
  2) The protein contents reduced by   in III instar larvae reared in Btk(Dipel). Thus the protein contents decreased to the maximum extent in larvae exposed to the highest sublethal concentration of Btk (Dipel).
  3) The detailed histoogical study of anterior view of longitudinal sections of midgut of the larvae, O.rhinoceros exposed to Btk (Dipel) showed marked changes in the structure o fthe epithelial cells, lumen of columnar epithelial cells and basement membrane in the midgut. Significant damage was observed in the selected cells of the midgut exposed to the highest concentration of Btk (Dipel) when compared to the lowest concentration of Btk (Dipel).
  4) This study revealed the significant toxic effect of Btk (Dipel) in the larvae O.rhinoceros. Btk (Dipel) caused damage on the physiology and biochemical constituents of larvae. Moreover, this strain is more toxic to O.rhinoceros. Therefore, it is recommended that the biocide treatment should be a prerequisite for saving the crops from the attack of coleopteran pest. The environment managers should maintain a strict vigil for proper and effective usage of biocide for pest management.In the era of Integrated pest Management, this study will provide an ample scope in the line of best management of pest. Proper awareness about the use of this biocides should be created in the mind s of public particularly farmers to enhance a high...