Activity of Bacillus thuringiensis hybrid protein against a lepidopteran and a coleopteran pest.

The use of Cry proteins from Bacillus thuringiensis are an important strategy for biological control. Recently it has been demonstrated that Cry hybrid proteins (by domain swapping) resulted in improved toxicities in comparison with parental proteins. Here, an SN1917 hybrid toxin was constructed and tested against Colombian pest insects Tecia solanivora (Lepidoptera: Gelechiidae), a severe potato pest, and Hypothenemus hampei (Coleoptera: Scolytidae), which attacks coffee crops. The SN1917 protoxin had a concentration causing 50% mortality (LC(50)) of 392 ng cm(-2), and SN1917 toxin showed an LC(50) of 201 ng cm(-2) against T. solanivora first instar larvae. The two parental toxins (Cry1B and Cry1I) used to make this new hybrid protein caused a mortality of 60% and 52%, respectively. Unfortunately, H. hampei first instar larvae proved to be resistant to the toxin. We conclude that SN1917 is an option for biological control and resistance management of T. solanivora. Implications for H. hampei are discussed.