Inheritance of resistance to Bacillus thuringiensis Cry1Ab protein in the sugarcane borer (Lepidoptera: Crambidae)

Document Type

Article

Publication Date

9-1-2009

Abstract

Inheritance traits of a Cry1Ab-resistant strain of the sugarcane borer, Diatraea saccharalis (F.) were analyzed using various genetic crosses. Reciprocal parental crosses between Cry1Ab-susceptible and Cry1Ab-resistant populations, F1 by F1 crosses, and backcrosses of F1 with the Cry1Ab-resistant population were successfully completed. Larval mortality of the parental and cross-populations were assayed on Cry1Ab diet and Bacillus thuringiensis (Bt)-corn leaf tissue. Maternal effects and sex linkage were examined by comparing the larval mortality between the two F1 populations. Dominance levels of resistance were measured by comparing the larval mortality of the Cry1Ab-resistant, -susceptible, and -heterozygous populations. Number of genes associated with the resistance was evaluated by fitting the observed mortality of F2 and backcross populations with a Mendelian monogenic inheritance model. Cry1Ab resistance in D. saccharalis was likely inherited as a single or a few tightly linked autosomal genes. The resistance was incompletely recessive on Bt corn leaf tissue, while the effective dominance levels (DML) of resistance increased as Cry1Ab concentrations decreased with Cry1Ab-treated diet. DML estimated based on larval mortality on intact Bt corn plants reported in a previous study ranged from 0.08 to 0.26. This variability in DML levels of Cry1Ab resistance in D. saccharalis suggests that Bt corn hybrids must express a sufficient dose of Bt proteins to make the resistance genes functionally recessive. Thus, Bt resistant heterozygous individuals can be killed as desired in the "high/dose refuge" resistance management strategy for Bt corn. © 2009 Elsevier Inc. All rights reserved.

Publication Source (Journal or Book title)

Journal of Invertebrate Pathology

First Page

44

Last Page

49

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