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

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 <i>CDA</i> gene, <i>TaCDA1</i>, in the invasive insect species <i>Tuta absoluta</i> (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 <i>TaCDA1</i> gene exhibited peak expression during the pupal stage, particularly within the epidermis. The suppression of <i>TaCDA1</i> expression through RNA interference in <i>T. absoluta</i> 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 ds<i>TaCDA1</i> + sucrose solution did not significantly impact <i>NtCDA1</i> expression or the mortality rate compared to the ds<i>GFP</i> + sucrose solution control in the non-target insect <i>Nesidiocoris tenuis</i>. This study demonstrated that <i>TaCDA1</i> is a potential and safe target for pest control of <i>T. absoluta</i>.