Spatio-Temporal Variation in Landscape Composition May Speed Resistance Evolution of Pests to Bt Crops
Fig 2
For model L, selection for resistance in H. armigera and H. punctigera under three scenarios about crop planting: (i) cotton (Bt and conventional) is only available in generations 2–4 (black lines); (ii) like (i) but 10% of cotton is also available for generation 5 (red lines and triangles); and (iii) like (i) but 10% of cotton is also available for generation 1 (green lines and circles).
The relative contributions of different crops and native vegetation for each of six years are based on field data from Cecil Plains. The top panels give K, the total available breeding habitat (Bt cotton, mandated refuges, and unmandated refuges) and the next-lower panels give Q, the proportion of breeding habitat that is refuge. Years are demarcated by vertical dashed lines. The 6-year patterns in Q and K are repeated in the simulations, so the values in first generation (first point on the left) arise from the values in the thirtieth generation (last point on the right). The next-lower panels are the log10 densities of eggs in refuges, measured before density-dependent mortality of larvae. The bottom panels give the strength of selection for resistance, Фt (Eq 1). For all simulations, F = 50, and habitat preferences are given in Table 1.