Chitin Deacetylase 1 Gene as an Optimal RNAi-Based Target for Controlling the Tomato Leaf Miner Tuta absoluta

Abstract

Chitin is a critical component of both the exoskeleton and internal structures of insects, which can protect insects from mechanical damage, dehydration and pathogen infection, and plays a significant role in the molting process. Chitin deacetylases (CDAs), key enzymes involved in chitin metabolism, are widely distributed among arthropods and microorganisms. In this study, we identified a CDA gene, TaCDA1, in the invasive insect species Tuta absoluta (Meyrick). Sequence analysis demonstrated a high degree of similarity to CDAs in other insects, revealing the presence of three conserved domains. Quantitative analysis showed that the TaCDA1 gene exhibited peak expression during the pupal stage, particularly within the epidermis. The suppression of TaCDA1 expression through RNA interference in T. absoluta pupae significantly impacted the expression of genes associated with chitin metabolism, increasing mortality and developmental abnormalities during the pupa–adult transition and reducing the pupal weight. Furthermore, soaking gene-specific dsRNA resulted in elevated mortality rates during the larva–pupa transition, causing the inability to form new cuticles or undergo ecdysis, as confirmed by subsequent histological observations. The oral administration of dsTaCDA1 + sucrose solution did not significantly impact NtCDA1 expression or the mortality rate compared to the dsGFP + sucrose solution control in the non-target insect Nesidiocoris tenuis. This study demonstrated that TaCDA1 is a potential and safe target for pest control of T. absoluta.