Fig. 2: Distributions of susceptibility factors and their impact on dose–response curves.

Blue dose–response curves represent infection probabilities in insects without Wolbachia, while green represent Wolbachia carriers. Insets depict distributions of susceptibility in noncarriers (blue) and carriers (green) normalised such that noncarriers have mean susceptibility one. Solid black lines represent the mean susceptibility of Wolbachia carriers, while dashed black curves mimic common procedures based on simple arithmetic ratios of the proportions infected dose-by-dose. Top panels (a–c) assume distributions of susceptibility factors with the same mean, less than one (0.2), and different variances (a, 0 (homogeneous); b, 0.0533; c, 0.160 (all-or-nothing)). Bottom panels (d, e) use the susceptibility distributions estimated in King et al.¹ (d, mean 1 and variance 0 for noncarriers, and mean 6.92 and variance 143 for carriers; e, mean 1 and variance 2.78 for noncarriers, and mean 1.49 and variance 10.9 for carriers). The threshold separating increased from reduced mean susceptibility is marked by dotted black lines.