*2.1.2 Resistance gene from higher plants*

Plants have co-evolved with insects for millions of years, and have developed many adaptations in terms of antifeeding and anti-shelter, among which digestive enzyme inhibitors (proteinase and amylase inhibitors) and lectins have shown significant effect on insects, which have been transferred into crop plants without major alteration, and expression has been at a similar level to codon-optimised Bt toxins [25].
