Insecticidal activity, putative binding proteins and histopathological effects of Bacillus thuringiensis Vip3(459) toxin on the lepidopteran pest Ectomyelois ceratoniae.

The carob moth, Ectomyelois ceratoniae, is an important agricultural pest that is susceptible to the Vip3(459) protein. The insecticidal activity, evaluated against this lepidopteran pest, displayed an LC50 value of about 28 ng/cm2. The investigation of the mode of action of this B. thuringiensis protein demonstrated that the active form of this toxin bound to putative receptors in the BBMV of E. ceratoniae. Ligand blotting experiment proved that Vip3(459) specifically bound to two proteins of about 53 and 57 kDa, located on the midgut. This specific binding caused perturbations in midgut tissues. The histopathology of 20 midguts from Vip3(459)-feeding larvae showed cytoplasm vacuolization, brush border membrane destruction, vesicle formation in the apical region and cellular disintegration. These findings suggested that B. thuringiensis Vip3(459) could be a promising biocontrol agent to eradicate E. ceratoniae and to prevent emergence of resistance.