The use of Cry toxins from Bacillus thuringiensis (Bt) is a breakthrough in the cultivation of transgenic Bt plants because of its high specificity and safety for the environment. However, a serious threat to the sustainability of this technology is the potential for insect populations to develop resistance to Bt toxins. It is important to understand the pathogen-insect interactions to extend the usefulness of products based on B. thuringiensis. Recent studies reported evidence of a tolerance mechanism associated with the immune response. Because of the importance of Alabama argillacea (Hubner, 1818) as a cotton pest, this research assessed its immunological alterations (cellular and humoral) when challenged with formulations of B. thuringiensis var. aizawai and B. thuringiensis var. kurstaki. The results suggest that the fourth instar larvae of A. argillacea do not have the potential to develop natural immune tolerance to the formulations based on B. thuringiensis. Dipel® led to a quantitative variation in all cell types, while XenTari® changed prohemocytes, plasmatocytes, granulocytes and oenocytoids. In insects treated with Dipel® there was no increase in the level of nitric oxide. These differences in response to treatments can be attributed to differences in the composition of the insecticides tested. The results indicate that the insecticide Dipel® caused significant changes in cellular and humoral immune system of fourth instar larvae of A. argillacea, while XenTari® caused only changes in the cellular immune system, furthermore Dipel® was faster to cause the cellular changes mentioned.