In vitro effects of RH-0345 and KK-42 on ecdysteroid levels and cuticle synthesis by pupal integument of mealworms
Berghiche, H.; Smagghe, G.; Soltani, N.
Communications in Agricultural and Applied Biological Sciences 68(1): 43-48
In this study, the effects of two insect growth regulators (KK-42 and RH-0345), applied either alone or in combination, were evaluated on the ecdysteroid production in vitro. Integument explants from the abdominal sternites of newly ecdysed pupae of mealworms, Tenebrio molitor, were cultured and the amounts of ecdysteroids, released into the culture medium, were determined by an enzyme immunoassay (EIA) after various intervals of incubation. In combined treatments, explants were cultured for the first two days in a medium added with the first compound and then transferred in new medium containing the second compound. EIA measurements showed that RH-0345, either alone or followed by KK-42, resulted in higher amounts of ecdysteroids as compared to controls. In contrast, KK-42 alone caused a significant reduction. But, when KK-42 was followed by RH-0345, the ecdysteroid amounts were equal to controls. In another series of experiments, the effects on cuticle secretion were examined. Only in the case that explants were treated with RH-0345, either alone or followed by KK-42, new cuticle synthesis was observed.