RESUMEN
Susceptible insect cell lines to specific pathogens of agricultural insect pests could be directly applied to special programs of their biological control; or this could be also used in the propagation of vectors of expression, such as baculovirus for genetic enginnering. In this paper, several attempts of establishing cell lines from different tissues of two Lepidoptera, Dione juno, an injurious pest of the fruit-bearing plants Passifloraceae and Methona themisto, a pest of an urban ornamental tree, Brunfelsia sp., are described. Two cell cultures could be obtained from D. juno: One, Dj-0387, from macerated neonate larvae and the other, Dj3-0687, from minced ovaries of 5th instar larvae. Their morphological characteristics, viability and populational growth rate were similar. Approximately after 60 passages in vitro for Dj-0387 and 40 passages for Dj3-0687, these cell cultures became inviable. Apparently, these numbers of passages were their critical age limit to establish in vitro. Otherwise, at the 30th passage, mainly in the case of Dj-0387, the origin of the "larval beings"was observed. This phenomenon could be explained by the presence of the imaginal discs of the newborn larvae, that could resume development in vitro.