Susceptibility of Spanish populations of the corn borers Sesamia nonagrioides (Lepidoptera : noctuidae) and Ostrinia nubilalis (Lepidoptera : Crambidae) to a Bacillus thuringiensis endotoxin

Baseline susceptibility to the Cry1Ab delta-endotoxin from Bacillus thuring iensis (Berliner) was determined for four populations of Sesamia nonagrioid es (Lefebvre) and two populations of Ostrinia nubilalis (Hubner) from Spain . This study shows that S. nonagrioides is at least as susceptible as O. nu bilalis to B. thuringiensis Cry1Ab protein. We found small differences in s usceptibility among the Spanish populations of S. nonagrioides that can be attributed to natural variation, because there are no records of B. thuring iensis products being used on corn crops in Spain. There were no difference s in susceptibility to Cry1Ab toxin between the two populations of O. nubil alis.