Fig. 5

RNAi-mediated knock-down of the expression of multiple cathepsin B genes reduces M. persicae survival and fecundity on A. thaliana. a Relative cathepsin B (CathB) expression levels (compared to aphids on dsGFP (control) plants) of M. persicae on three independent transgenic lines (lines 5–1, 17–5 and 18–2) producing double-stranded (ds) RNA corresponding to multiple M. persicae cathepsin B genes (dsCathB) (Fig. 3a, Additional file 20: Figure S10). Aphids were reared on the transgenic lines for four generations. Batches of five adult females were harvested for RNA extraction and qRT-PCR assays. Bars represent expression values (mean ± standard deviation (SD)) of three independent biological replicates. b CathB-RNAi M. persicae produces less progeny compared to control (dsGFP-treated) aphids on A. thaliana. Five nymphs were transferred to single plants and produced nymphs on approximately day 5. Nymph counts were conducted on days 7, 9 and 11 and removed. Columns show the mean ± SD of the total nymph counts for these three days of three biological replicates, with each replicate consisting nymphs produced by 15 aphids at five aphids per plant (n = 3 plants). c, d Survival rates of CathB-RNAi and control (dsGFP-exposed) M persicae on non-transgenic A. thaliana (At) and N. benthamiana (Nb) plants. Ten third instar nymphs on dsCathB and dsGFP transgenic plants were transferred to non-transgenic plants; survival rates were recorded two days later. Bars represent mean ± SD of three biological replicates, with each replicate consisting of the survival rates of 30 aphids at 10 aphids per plants (n = 3 plants). e, f Fecundity rates of CathB-RNAi and control (dsGFP-exposed) M. persicae on non-transgenic A. thaliana (At) and N. benthamiana (Nb) plants. Nymph counts were conducted as in (b). Asterisks (*) and different letters (a, b) above the bars indicate significant difference at p < 0.05 (ANOVA with Fisher’s LSD to control for multiple tests)