Date of Award
Master of Science
Transgenic maize hybrids containing event DAS-59122-7 have been genetically modified to produce the insecticidal Bacillus thuringiensis (Bt) proteins Cry34Ab1 and Cry35Ab1. This transgenic maize protects against root feeding injury by the western corn rootworm, Diabrotica virgifera virgifera (LeConte), and has been cultivated commercially since 2005. Widespread use of maize containing this event increases the potential for insects to evolve resistance. One method for assessing this potential is to investigate the inheritance of resistance with laboratory-selected insect strains. Inheritance of resistance to DAS-59122-7 maize was characterized using two laboratory-selected strains and a seedling-based bioassay system. Neonates from several genotypes were exposed to mats of DAS-59122-7 seedlings as well as mats of non-Bt seedlings for a prescribed duration. Larvae were then extracted and characterized for susceptibility based on larval development. Development when fed DAS-59122-7 maize seedlings was significantly faster for resistant colonies than susceptible colonies although slower than development of these colonies on non-transgenic maize. Results from reciprocal crosses were indicative of autosomal non-recessive inheritance. No fitness cost to the resistance in these strains was observed based on larval development on non-transgenic maize. Two independent larval development measurements were taken to assess population susceptibility to DAS-59122-7: instar and body area. Results indicated that both measures were suitable for differentiating susceptibility to DAS-59122-7 maize.
Stephen Drew Thompson
Thompson, Stephen Drew, "Characterization of inheritance of resistance to maize containing event DAS-59122-7 in laboratory selected colonies of western corn rootworm using the sub-lethal seedling assay" (2014). Graduate Theses and Dissertations. 14043.