Bacillus thuringiensis (Bt) is a bacterial species noted for the
insecticidal nature of some of its isolates, this insecticidal character
is primarily conferred by insecticidal crystal proteins (ICPs) whose
genes are mainly located on mega plasmids (Raymond et al., 2010).
These ICPs have been classified as Cry1-Cry72, Cyt1-Cyt2, and are
named according to their sequence similarity (see the B. thuringiensis
toxin nomenclature website at http://www.lifesci.susx.ac.uk/
home/Neil_Crickmore/Bt/). Besides the extensive use of biological
insecticides containing B. thuringiensis strains, genetically modified
crops expressing B. thuringiensis toxin genes (Bt crops) have resulted
in successful and environmentally sound insect pest control
(Kumar et al., 2008). The Cry2A toxins form a group whose members
display activity against lepidopteran and/or dipteran larvae
(McNeil and Dean, 2011). Recent data have shown that Cry2Ae
does not share binding sites with several Cry1 and Vip3A toxins
on BBMV from larvae of most commercially relevant heliothine
species (Gouffon et al., 2011). This result supports the potential
of combining Cry2A toxins with others in order to increase target
range and to delay the onset of resistance. The Cry2A toxins are
particularly interesting in that significant differences in specificity
are reflected by relatively small differences in sequence (Morse