Assessing durability of Bt crops where insect resistance genes are linked

Models of pesticide resistance evolution commonly assume that genes for insect resistance are unlinked, despite limited supporting evidence. Although this assumption has been justified on theoretical grounds, few studies have examined the sensitivity of crop durability to genetic linkage in complex agricultural landscapes. We use the RAMAS IRM modeling software to assess the rates of pest resistance evolution for each of several spatially structured, multi-toxin landscape scenarios under low, moderate, and high rates of genetic recombination among resistance loci. We use our results to identify realistic conditions under which linkage can strongly affect estimates of resistance evolution, and more generally to assess the need for incorporating genetic linkage in models of pesticide resistance and PIP durability.