Establishment and characterization of novel cell lines derived from six lepidopteran insects collected in the field

Insect cell lines are used to study cellular interactions and gene functions in vitro in several research areas. However, suitable cell lines for experiments are not always available, especially in non-model species. Here, we established novel cell lines derived from fat bodies of six lepidopteran insects: Cydia kurokoi (named NARO-Cyku), Cephonodes hylas (NARO-Cehy), Haritalodes basipunctalis (NARO-Haba), Theretra oldenlandiae (NARO-Thol), Lymantria dispar (NARO-Lydi), and Hyphantria cunea (NARO-Hycu) collected in the field. The larval fat body was a promising tissue for the starting material when samples were limited due to field collection. It was critical that the medium volume was kept to a minimum for primary culture to maintain adherence of the fat body cells to the flask. The flask was coated with poly-L-lysine for effective induction of adherence and cell division. The identities of cell lines were confirmed using DNA barcoding with the mitochondrial cytochrome c oxidase I gene after cultures were passaged over 50 times. All lines except for NARO-Lydi and NARO-Hycu are adherent cells, and population doubling time of six cell lines ranged from 1.03 to 2.49. Induction of gene expression was practicable in the four adherent cell lines as revealed by transfection of expression vectors and found the immediate early 2 and the Bombyx actin 3 were effective gene promoters. The results suggest that these cell lines are capable of gene functional analysis. Thus, establishments of cell line using our methods for non-model lepidopterans could make a practical contribution to pest management and insect utilization.