Spatio-Temporal Variation in Landscape Composition May Speed Resistance Evolution of Pests to Bt Crops
Fig 4
For models L, A and I, the effects of variation in Q and/or K for four scenarios: (i) only Q varies, with Q1 = 0.05 and Q2 ranging from 0.05 to 0.2 (indicated on the horizontal axis labeled "Variation" which is scaled from 0 to 1 as Q2 goes from 0.05 to 0.2), while K1 = K2 = 1 (solid line); (ii) only K varies, with K1 = 1 and K2 in the ranging from 1 to 0.25 (indicated by values of "Variation" ranging from 0 to 1), while Q1 = Q2 = 0.05 (dashed line); (iii) Q and K vary asynchronously, with Q1 = 0.05 and Q2 ranging from 0.05 to 0.2, and K1 = 1 and K2 ranging from 1 to 0.25 (↑Q↓K, dotted line); and (iv) Q and K vary synchronously, as in (iii) but with high values of Q2 coinciding with high values of K2 (↑Q↑K, dot-dashed line).
(A-C) give the times to control failure (when resistance allele frequency reaches 0.5) for models L, A, and I, respectively. (D-F) give the strength of selection Фt (Eq 1) for four consecutive generations for models L, A and I, respectively, and for scenarios (i)—(iv). (G-H) give the densities of eggs (numbers/[QtKt]) in refuges before density-dependent mortality and averaged over both generations for models L and A, respectively. (I) The predicted relative time to control failure from the approximation giving Tc (Eq 2) and the observed time to control failure for all of the simulated runs for all three models shown in (A-C). Other parameter values are: F = 50, s1 = 0.01, s2 = 0.01, and h1 = h2 = 0.05.