Figure 4. Survival of pea aphids after oral infection by wt and mutants of D. dadantii 3937.

Survival is shown for aphids treated with wt bacteria (red), arnB (green), dltB (blue), and dltB arnB (brown) mutants. Results were obtained with 2×30 third instar aphid nymphs per treatment, including a diet-treated control (no mortality, not shown). The experiment was repeated twice with very similar results (p<0.06 in all comparisons of wt with arnB mutants). Median survival times (LT50s) were calculated with a Weibull fit (inlet), and give the following series [95% confidence intervals]: wt, 2.92 [2.18–3.92]; arnB, 4.74 [3.42–6.55]; dltB 3.58 [2.62–4.88] and arnB-dltB double mutant, 4.46 [3.23–6.18].