Fig. 1

Cuticular thickening mediates malathion penetration resistance in B. dorsalis. A Penetration rate of malathion in MR and MS strains. Each eluant of MR and MS strains contained 30 and 50 5-day-old adult flies, respectively (n = 3). B Chitin content and expression of CHS1 in MR and MS strains. Each sample contained six 5-day-old adult flies (n = 4). C The chitin content (mg of D-glucosamine per g of flies) and expression of CHS1 was analyzed after silencing CHS1. Each sample contained six 5-day-old adult flies. Data are means ± SEM (n = 4). D Ultrastructure of the pronotum cuticle in MR, MS, dsGFP and dsCHS1 groups. E Pronotum cuticular thickness in strains MR (n = 10), MS (n = 7) and after silencing CHS1 (n = 10). Each thickness value is the mean of five randomly selected cross-sectional measurements. F Penetration rate of malathion after silencing CHS1. Each sample contained 30 5-day-old adult flies (n = 3). G The effect of CHS1 silencing on malathion susceptibility in B. dorsalis. Survival rate was observed at 0–3 day after malathion exposure (n = 120)