Effects of ingested 20-hydroxyecdysone on development and midgut epithelial cells of Plodia interpunctella (Lepidoptera, Pyralidae)

We describe the effects of ingested 20-hydroxyecdysone on larvae of Plodia interpunctella. It caused significant mortality and provoked cannibalism between larvae. On the other hand, it also induced precocious pupation and adult emergence. A large weight loss of larvae was recorded. Besides, 20-hydroxyecdysone provoked a reduction in protein, glycogen and lipid contents. Using electron microscopy, we have shown that 20-hydroxyecdysone caused a dose-dependent severe cytotoxicity on the midgut epithelial cells, resulting in the disorganization and the vacuolization of the cytoplasm; the nucleus appeared with crenulated envelope and presented many clear areas between the chromatin clumps and finally, the disruption of microvilli and the rupture of the plasma membrane led to the shedding of cytoplasm contents into the midgut lumen. In conclusion, ingested 20-hydroxyecdysone shows potent growth disruptive effects on P. interpunctella.