Resistance against Bacillus thuringiensis endotoxins in a laboratory population of Helicoverpa armigera is based on an elevated immune status

Muhammad Sarjan (Faculty of Agriculture, University of Mataram, Indonesia)
Mahbub M Rahman (Insect Molecular Biology, School of Agriculture, Food and Wine, University of Adelaide)
Gang Ma (Insect Molecular Biology, School of Agriculture, Food and Wine, University of Adelaide)
Otto Schmit (Insect Molecular Biology, School of Agriculture, Food and Wine, University of Adelaide)

Jurnal Ilmu Dasar
Vol 10 No 1 (2009)

Recent   observations   suggest   that   lectin-like   toxins,   such   as   endotoxins   from  Bacillus   thuringiensis  are sequestered inside the gut of immune-induced insects providing tolerance to Bt-formulations. To investigate the induction   and   sequestration   process,   we   used   toxin   and   lectins   that   bind   to   galactosamine   (Gal)   and   N-acetylagalactosamine (GalNAc) to identify binding sites in the midgut of induced and non-induced insects using confocal   microscopy.   Our   observations   suggest   that   immune   and   metabolic   hemolymph   components   are transported across the gut epithelium and accumulate inside the gut lumen in Bt-tolerant insects. Co-location of immune components and toxin indicates that some of the toxin is inactivated by coagulation reactions inside the gut lumen before it can reach the brush border membrane