FASN1 or DGAT2 silencing or PPD treatment delayed growth and development of Serratia-infected aphids. (a) FASN1 and (b) DGAT2 expression in Serratia-infected aphids after feeding with dsFASN1 and dsDGAT2, respectively (n = 6). (c,d) Effects of silencing FASN1 and DGAT2 on the nymphal period and the body weight, respectively (n = 10–15). Data were compared with those of nymphs fed with dsGFP. (e) FASN1 and DGAT2 expression levels of Serratia-infected aphids fed with PPD within 36 h (n = 6). (f,g) Effects of pharmacological inhibitor PPD on the nymphal period and body weight, respectively (n = 6–11). Data were compared with those of nymphs fed with DMSO. (h,i) Triglyceride contents were detected in Serratia-infected aphids fed with (h) dsFASN1/dsDGAT2 and (i) PPD (n = 8). (j) Lipid droplets changes in fat body of Serratia-infected aphids fed with dsRNA or PPD using Nile red staining. Scale bar = 50 μm, n > 5. Box plots represent the median (bold black line), quartiles (boxes), as well as the minimum and maximum (whiskers). Values in bar plots represented means ± SE (* p < 0.05; ** p < 0.01; *** p < 0.001); ns, non-significant difference.