Cell Toxicity Evaluation of Some Ecdysteroid Agonist Insecticides Using Three Different Cell Lines

Ecdysteroid agonist insecticides, such as methoxyfenozide and tebufenozide are a group of insecticides that provoke a precocious and lethal larval molting in susceptible insects. As these compounds have selective properties, they can be used in integrated pest management (IPM) programs. Insect cell lines are useful in vitro laboratory tools which are exploited in physiology, toxicology and screening research of these compounds. In the present research, cell proliferation inhibition activity of methoxyfenozide, tebufenozide, halofenozide and RH-5849 was evaluated using three different cell lines, two lepidopteran cells (Choristoneura fumiferana, CF-203 of the spruce budworm and Bombyx mori, Bm5) and one dipteran cell, Drosophila melanogaster, S2. The order of toxicity of the compounds in both lepidopteran cell lines was methoxyfenozide>tebufenozide>20E>halofenozide>RH 5849, while methoxyfenozide and tebufenozide showed similar toxicity in S2 cells. Moreover, in S2 cells, all compounds exhibited lower biological activity with higher EC50 values. For example, methoxyfenozide showed 245 and 77-fold lower toxicity in CF-203 and Bm5 cells, respectively. As lepidopteran cell lines exhibit better biological potency than dipteran S2 cell, therefore it could be suggested that CF-203 and Bm5 cell lines are suitable for screening programs and also for mode of action research of these compounds.