Pellino, a highly conserved E3 ubiquitin ligase, is known to mediate ubiquitination of phosphorylated Interleukin-1 receptor-related kinase (IRAK) homologs in Toll signaling pathway. To understand the immunological function of TmPellino, we screened the knockdown efficiency of TmPellino by injecting TmPellino-specific dsRNA into T. molitor larvae. Subsequently, we investigated the larval mortality and the tissue-specific expression patterns of antimicrobial peptide (AMP) genes against microbial challenges. Interestingly, the results indicate that the expression of many AMP genes was upregulated in the Malpighian tubules of TmPellino-silenced T. molitor larvae. This study may provide basic information to understand how Tmpellino regulates AMPs production in T. molitor.