BackgroundTea geometridEctropis grisescens(Geometridae: Lepidoptera), is one of the most destructive defoliators in tea plantations in China. The MAPK cascade is known to be an evolutionarily conserved signaling module, acting as pivotal cores of host–pathogen interactions. Although the chromosome-level reference genome ofE. grisescenswas published, the whole MAPK cascade gene family has not been fully identified yet, especially the expression patterns of MAPK cascade gene family members upon an ecological biopesticide,Metarhizium anisopliae, remains to be understood.ResultsIn this study, we have identified 19 MAPK cascade gene family members inE. grisescens, including 5 MAPKs, 4 MAP2Ks, 8 MAP3Ks, and 2 MAP4Ks. The molecular evolution characteristics of the whole Eg-MAPK cascade gene family, including gene structures, protein structural organization, chromosomal localization, orthologs construction and gene duplication, were systematically investigated. Our results showed that the members of Eg-MAPK cascade gene family were unevenly distributed in 13 chromosomes, and the clustered members in each group shared similar structures of the genes and proteins. Gene expression data revealed thatMAPKcascade genes were expressed in all four developmental stages ofE. grisescensand were fairly and evenly distributed in four different larva tissues. Importantly, most of theMAPKcascade genes were induced or constitutively expressed uponM. anisopliaeinfection.ConclusionsIn summary, the present study was one of few studies on MAPK cascade gene inE. grisescens. The characterization and expression profiles of Eg-MAPK cascades genes might help develop new ecofriendly biological insecticides to protect tea trees.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12864-023-09446-7.