Cry proteins, of which Cry3Bb1 is only one, act by selectively
binding to specific sites localized on the lining of the midgut of
susceptible insect species. Following binding, pores are formed
that disrupt midgut ion flow, causing gut paralysis and eventual
death due to bacterial sepsis. Cry3Bb1 is lethal only when eaten by
the larvae of coleopteran insects (i.e., beetles), and its
specificity of action is directly attributable to the presence of
specific binding sites in the target insects.