RESUMO
The sugarcane borer, Diatraea saccharalis (F.), is one of the major target pests of transgenic maize, Zea mays, expressing Bacillus thuringiensis (Bt) proteins in South America and mid-southern region of the U.S. The MON89034 maize expresses Cry2Ab2 and Cry1A.105 Bt proteins and it was developed to provide better control of key lepidopteran pests of maize including D. saccharalis. The objectives of this study were to select and characterize the resistance of D. saccharalis to Cry2Ab2 using a non-commercial Cry2Ab2 single gene Bt maize line. A Cry2Ab2-resistant strain (Cry2Ab2-RR) of D. saccharalis was established from 28 two-parent families collected from fields in northeast Louisiana, U.S. The Cry2Ab2-RR showed a high level of resistance to Cry2Ab2 in both diet-incorporated and whole maize plant bioassays. The Cry2Ab2 resistance in D. saccharalis was likely inherited as a single or a few tightly linked autosomal genes. The resistance was non-recessive and not associated with fitness costs. The results should provide valuable information in resistance monitoring, assessing resistance risk, and developing effective management strategies for the sustainable use of Bt maize technology for managing maize stalk borers.
Assuntos
Proteínas de Bactérias/genética , Endotoxinas/genética , Proteínas Hemolisinas/genética , Resistência a Inseticidas/genética , Mariposas/genética , Controle Biológico de Vetores/métodos , Plantas Geneticamente Modificadas/genética , Zea mays/parasitologia , Animais , Bacillus thuringiensis/genética , Toxinas de Bacillus thuringiensis , Zea mays/genéticaRESUMO
Wireworms are a common soil-dwelling pest of maize, Zea mays L., in the midwestern United States. Wireworms are a problematic group to control and study due to the difficulty involved in identification. The objectives of this study are to identify this species complex of wireworms by using molecular diagnostic techniques and to reconstruct a phylogeny of economically important wireworm species. The cytochrome oxidase I gene of mitochondrial DNA was sequenced from > 300 individuals. The species analyzed include all economically important members of the genus Melanotus Eschscholtz as well as Conoderus lividus (De Geer). The species that are indistinguishable in the larval stage were successfully separated using nucleotide p-distances, and sequence data were then used in phylogenetic analyses. The data presented here represent an initial phylogenetic hypothesis concerning economically important wireworms. Our results indicate that the molecular phylogeny of the mitochondrial cytochrome oxidase subunit I gene provides a fast and accurate method of separating wireworm species. By increasing the ease and accuracy of identification, we hope to facilitate further investigations into their biology and control.