Mahon R J, Olsen K M
CSIRO Entomology, GPO Box 1700, Canberra, ACT 2601, Australia.
J Econ Entomol. 2009 Apr;102(2):708-16. doi: 10.1603/029.102.0232.
Bollgard II cotton (which expresses two Bt insecticidal genes cry1Ac/cry2Ab) and conventional cotton, grown in the laboratory or field and sampled at different stages, was exposed to Helicoverpa armigera (Hübner) larvae of three genotypes: homozygous for resistance to Cry2Ab; homozygous for susceptibility to Cry2Ab, and heterozygous for resistance. Survival of all genotypes was limited on Bollgard II but increased as plants aged. This was particularly the case for homozygous resistant individuals, with 8.5% of this genotype surviving to pupation on mature cotton. The increasing survival is assumed to be caused by the decline in the titer of Cry1Ac toxin after flowering in Bollgard II because Cry2Ab homozygous resistant larvae can tolerate high levels of Cry2Ab toxin. Larvae heterozygous for resistance performed no better on Bollgard II than homozygous susceptible larvae. Survivors on Bollgard II grew more slowly and produced smaller pupae that yielded adults with reduced longevity and fecundity. When reared on conventional cotton, all genotypes generally performed equally, indicating an absence of fitness costs associated with Cry2Ab resistance under the conditions examined.
在实验室或田间种植并在不同阶段取样的双价抗虫棉（表达两种Bt杀虫基因cry1Ac/cry2Ab）和常规棉花，被暴露于三种基因型的棉铃虫幼虫：对Cry2Ab抗性纯合；对Cry2Ab敏感纯合，以及抗性杂合。所有基因型在双价抗虫棉上的存活都受到限制，但随着植株变老而增加。对于抗性纯合个体尤其如此，该基因型有8.5%在成熟棉花上存活到化蛹。存活增加被认为是由于双价抗虫棉开花后Cry1Ac毒素滴度下降所致，因为Cry2Ab抗性纯合幼虫能够耐受高水平的Cry2Ab毒素。抗性杂合幼虫在双价抗虫棉上的表现并不比敏感纯合幼虫更好。双价抗虫棉上的存活幼虫生长更缓慢，化蛹更小，羽化出的成虫寿命缩短、繁殖力降低。当在常规棉花上饲养时，所有基因型的表现通常相同，表明在所研究的条件下，与Cry2Ab抗性相关的适合度代价不存在。
