Insect midgut peritrophic membrane (PM) is a functional structure that protects insects against chemical damage and microorganism infection. The essential component in PM is chitin and its synthesis is catalyzed by Class B chitin synthase (CHSB), which plays a unique role in chitin-containing organisms and thus represents a potential target for eco-friendly pesticides. cDNA and gDNA of CHSB from a widely spread pest Ostrinia furnacalis (OfCHSB) were obtained and their sequences and transcription patterns were characterized. Results indicated that OfCHSB may be indirectly stimulated by ecdysone because the binding sites of only early ecdysone-inducible elements (BR-C and E74A) rather than ecdysone response elements (EcR and USP) were found within the core promoter of OfCHSB. In addition, the transcripts of OfCHSB increased in vivo at the feeding stage of the 4th and 5th instar larvae. The subcellular localization of OfCHSB was studied using an insect midgut cell line. Puncta structures of the recombinant OfCHSB were observed co-localized with Golgi marker Man II-GFP, suggesting a possible localization of chitin synthases under physiological conditions. (C) 2010 Elsevier Inc. All rights reserved.