Figure 5: Impact of withanolides on infected H. subflexa and H. virescens larvae.

(a) Proportion of HS and HV larvae which were able to grow on diet containing 5 × 10⁵ CFU per ml Bt spores with or without withanolide treatment. Increasing withanolide concentrations are indicated by a grey gradient. A generalized least squares method (glm) was used to test for differences between the species (P<0.0001). (b) Kaplan–Meier survival plot of HS larvae fed on (i) 5 × 10⁵ CFU per ml Bt spores, (ii) 5 × 10⁵ CFU per ml Bt spores and 100 μg ml⁻¹ withanolides and (iii) 5 × 10⁵ CFU per ml Bt spores and 150 μg ml⁻¹ withanolides. (c) Kaplan–Meier survival plot of HV larvae fed on (i) 5 × 10⁵ CFU per ml Bt spores, (ii) 5 × 10⁵ CFU per ml Bt spores and 100 μg ml⁻¹ withanolides and (iii) 5 × 10⁵ CFU per ml Bt spores and 150 μg ml⁻¹ withanolides. Significant differences are indicated by ***P<0.001; **P<0.01, NS, not significant (Cox regression survival analysis). See Supplementary Table 6 for significance values.