Abstract: 【Aim】MicroRNAs (miRNAs) play a pivotal role in important life processes such as reproduction, development and immunity in insects. The aim of this study is to explore the impact of overexpression and knockdown of ame-miR-13b on the expression of target genes in Apis mellifera ligustica larvae, so as to provide theoretical and experimental bases for further investigation of regulation mechanism of ame-miR-13b underlying the development of A. m. ligustica larval gut. 【Methods】 Based on the nucleotide sequence of ame-miR-13b, the sequences of the corresponding mimic-ame-miR-13b and inhibitor-ame-miR-13b and their counterpart controls mimic-NC and inhibitor-NC were designed and synthesized, and then mixed with the diet which was used to feed the 3-day-old larvae for 6 times with the diet changed every 12 h to perform overexpression and knockdown of ame-miR-13b, respectively. RT-qPCR was performed to detect the expression levels of ame-miR-13b and target genes Ecr, Egfr and P450 18a1 in the larval gut of A. m. ligustica after overexpression and knockdown of ame-miR-13b. 【Results】 The expression levels of ame-miR-13b in the guts of the 4- and 6-day-old larvae of A. m. ligustica fed with mimic-ame-miR-13b were significantly up-regulated as compared to that in the group fed with mimic-NC, and those in the guts of the 4-day-old larvae and in the guts of the 5- and 6-dayold larvae fed with inhibitor-ame-miR-13b were down-regulated and significantly down-regulated, respectively, as compared to that in the group fed with inhibitor-NC. After overexpression of ame-miR-13b, the expression level of Egfr in the gut of the 6-day-old larvae was significantly decreased, while those of Ecr and P450 18a1 were significantly increased as compared to that in the group fed with mimic-NC. After knockdown of ame-miR-13b, the expression of Egfr in the gut of the 6 day-old larvae was up-regulated insignificantly, that of Ecr was significantly up-regulated, whereas that of P450 18a1 was significantly down-regulated as compared to that in the group fed with inhibitor-NC. 【Conclusion】 Overexpression and knockdown of miRNA in larval individuals of A. m. ligustica are successfully achieved by feeding method. There is a potential negative regulatory relationship between ame-miR-13b and Egfr.

Key words: Apis mellifera ligustica, larva, gut, microRNA, ame-miR-13b, target gene