Molecular identification of the chitinase genes in Aedes albopictus and essential roles of AaCht 10 in pupal-adult transition

Background Aedes albopictus is an increasingly serious threat in public health due to it is vector of multiple arboviruses that cause devastating human diseases, as well as its widening distribution in recent years. Insecticide resistance is a serious problem worldwide that limits the efficacy of chemical control strategies against Ae. albopictus . Chitinase genes have been widely recognized as attractive targets for the development of effective and environmentally safe insect management measures. Methods Chitinase genes of Ae . albopictus were identified and characterized on the basis of bioinformatics search of the referenced genome. Gene characterizations and phylogenetic relationships of chitinase genes were investigated, and spatio-temporal expression pattern of each chitinase gene was evaluated using qRT-PCR. RNA interference (RNAi) was used to suppress the expression of AaCht 10, and the roles of AaCht 10 were verified based on phynotype observations, chitin content analysis and hematoxylin and eosin (H&E) stain of epidermis and midgut. Results Altogether, 14 chitinase-related genes (12 chitinase genes and 2 IDGF s) encoding 17 proteins were identified. Phylogenetic analysis showed that all these AaCht s were classified into seven groups, and most of them were gathered into group IX. Only AaCht 5-1, AaCht 10 and AaCht 18 contained both catalytic and chitin-binding domains. Different AaCht s displayed development- and tissue-specific expression profiling. Suppression of the expression of AaCht 10 resulted in abnormal molting, increased mortality, decreased chitin content and thinning epicuticle, procuticle and midgut wall of pupa. Conclusions Findings of the present study will aid in determining the biological functions of AaCht s and also contribute to using AaCht s as potential target for mosquito management. Graphical Abstract