Evolution of Z chromosome in Ostrinia furnacalis: dosage compensation, sex-biased gene expression and evolutionary rate of Z-linked genes.

BACKGROUND: Sex chromosome evolution and its related regulatory genes play a significant role in insect physiological processes such as sex determination, growth and development, and reproduction, with target genes having potential application in the research and development of technologies such as RNA interference (RNAi) pesticides. However, Z chromosome evolution in Ostrinia furnacalis Guenée (Lepidoptera: Crambidae) is not clear. Here, RNA sequencing, molecular evolutionary analysis, and RNAi were used to study Z chromosome evolution and the function of Male-specific lethal (MSL) complex genes in O. furnacalis.

RESULT: We found that most tissues and life stages showed complete and global dosage compensation of the Z chromosome. Two MSL complex genes, mle and msl3, regulate Z chromosome dosage in females. MSL complex genes also have important roles in the growth and development of O. furnacalis, especially for females. Furthermore, in almost all tissues and life stages of O. furnacalis, sex-biased genes were distributed non-randomly in the genome and evolved faster than unbiased genes. In wing, thorax, and antenna, we detect several sex-biased genes that are related to differences in wing color, locomotor activity levels and olfactory function between the sexes. In addition, the Fast-Z effect was absent in O. furnacalis, and even acted as a slightly 'Slow-Z', suggesting that purifying selection on recessive deleterious mutations has a major role in O. furnacalis.

CONCLUSION: Our findings lay the foundations for understanding Z chromosome evolution and MSL complex function, which have important theoretical significance for developing new green pest prevention and control technologies. © 2026 Society of Chemical Industry.