Fitness costs of Cry1Ab resistance in a field-derived strain of Ostrinia nubilalis (Lepidoptera: Crambidae).
The study of fitness costs associated with resistance to toxins from Bacillus thuringiensis Berliner (Bt) in Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae) is important for understanding resistance evolution and for evaluating resistance management practices that prevent or mitigate resistance to transgenic corn, Zea mays L. Resistant individuals identified from a field collection in Kandiyohi, MN, were used to generate a Cry1Ab-resistant strain. We used susceptible and resistant strains with similar genetic background to establish crosses and estimate dominance of fitness costs by measuring fitness components and population parameters determined by fertility life tables. Spermatophore volume and mating frequency also were compared to identify potential effects of resistance on fertility. Inheritance of fitness costs in O. nubilalis varied from recessive to incompletely recessive among the parameters evaluated. Selection for resistance to Cry1Ab significantly reduced the fitness of O. nubilalis. Resistant insects exhibited reduced pupal weight and increased developmental time compared with susceptible and F1 larvae derived from reciprocal crosses of resistant and susceptible parents. In addition, it was observed that resistant insects exhibited a higher proportion of unsuccessful matings and lower fertility than the susceptible strain. Despite the differences observed in resistant insects, our results did not indicate strong evidence of fitness costs in the F1 progeny.
Crespo
André L B
AL
Department of Entomology, University of Nebraska-Lincoln, Lincoln, NE 68583-0816, USA.
Spencer
Terence A
TA
Tan
Sek Yee
SY
Siegfried
Blair D
BD
D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000494:pharmacology*; D004731:Endotoxins / Q000494:pharmacology*; D005260:Female; D006460:Hemolysin Proteins / Q000494:pharmacology*; D007305:Insecticide Resistance; D007814:Larva; D008297:Male; D009036:Moths / Q000187:drug effects* / Q000235:genetics; D011679:Pupa; D012726:Sexual Behavior, Animal; D013093:Spermatogonia
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis