E. coli-generated dsRNA targeting ribosomal protein L10, S11, and arginine kinase via oral administration impairs larval development in Tuta absoluta.

Tuta absoluta considerably damages tomato, potato, brinjal, sweet pepper, and tobacco in greenhouses and open fields on a global scale. RNA interference (RNAi) represents a promising control strategy. In this study, arginine kinase, ribosomal protein L10, and S11 encoding genes, TaArgK, TaRpL10, and TaRpS11, were selected. The three genes were stably expressed throughout the entire developmental excursion, from egg to adult. They were evenly transcribed in the head, foregut, midgut, hindgut, fat body, epidermis, and hemolymph of 2-day-old fourth-instar larvae. The RNAi efficacy of oral administration of dsRNA generated by Escherichia coli HT115 (DE3) strain and of microinjection of in vitro produced dsRNA was compared in the third instar larvae. The larvae that gnawed on dsRNA-immersed potato and tomato foliage for 24, 48, and 72 hours obtained 5.55, 11.1, and 16.65 μg, and 3.06, 6.12, and 9.18 μg of dsRNA, respectively. Ingestion of dsArgK, dsRpL10, or dsRpS11 caused an average reduction of target mRNA by 30.7%, 41.1%, and 61.4%, respectively, leading to 19.1%, 7.9%, and 17.4% of larval lethality, and reduced adult emergence by 33.6%, 27.2%, and 45.0%, respectively. A microinjection of 0.1 μL dsRNA solution introduced a total of 0.71 μg of dsRNA into the larva, but no RNAi effects were observed. Given that E. coli has been extensively used to safely and cost-efficiently produce dsRNA for large-scale agricultural implementation, our findings suggest the possibility that bacterially-expressed dsRpS11 and dsArgK may be used via a spray-induced gene silencing method in the field to protect growing crops against T. absoluta.