Some resistant strains ofP. interpunctella, P.xylostella, and H. virescensshowed to have lost (or have
reduced) the capacity to bind Cry1A-type proteins. A different mechanism involves alterations in the gut pro-teinase activities that interact with B. thuringiensistoxins (e.g. P. interpunctellaand inH. virescens). Absence of a major
gut protease associated with Cry1Ac protoxin activation was demonstrated in the 198r colony of P. interpunctella