Development and characterization of Spodoptera mauritia ovarian primary cell culture and evaluation of fenoxycarb toxicity.

The rice swarming caterpillar, Spodoptera mauritia (Biosduval, 1833) (Lepidoptera: Noctuidae), has been considered a severe pest and has caused the extreme loss of rice paddies in the nursery stages. The massive reproductive efficiency of pests results from balanced endocrine functioning. Insect treatments with exogenous either juvenile hormones (JH) or juvenile hormone analogues (JHAs) during low endogenous JH titers disrupt metamorphosis and ovarian development. Hence, it was thought worthwhile to develop a primary ovarian cell culture of Spodoptera mauritia to study the biological efficiency of JHA, fenoxycarb, at the cellular level. The study envisioned the cell characteristics and growth properties and found that most cells were spherical. Spindle-shaped cells were also present during the initial stage of active cell division. The majority of the cells grew attached to the bottom of the culture plates, and a few grew in suspension. The cell doubling time was 144 ± 14 h. The growth curve exhibited a sigmoid pattern of cell proliferation at first, followed by a declining phase. These properties indicate that the primary ovarian culture is a suitable candidate for developing a novel cell line of S. mauritia. The preliminary study investigated the cytotoxicity of the insect growth regulator fenoxycarb in ovarian, primary cell culture. Incubated cells showed noticeable morphological changes, including cell shrinkage and apoptotic body formation; inhibition of cellular proliferation; and apoptosis-inducing effects in ovarian, primary cell culture of S. mauritia. Evidently, from these results, it is clear that juvenile hormone mimics can react in a meaningful way to control the rice pest S. mauritia by inducing cellular apoptosis in ovarian cells, which may cause adult females to become sterile.