Tolerance of the Egyptian cotton leafworm Spodoptera littoralis (Lepidoptera: Noctuidae) to ingested phytoecdysteroids

The Egyptian cotton leafworm Spodoptera littoralis is remarkably resistant to exogenous ecdysteroids, and is able to tolerate both prolonged exposure to artificial diets containing up to 100 ppm 20-hydroxyecdysone (20E) and single dose administration of up to 10 mu g ecdysone or 20E without any adverse effects on growth and development. In addition, it feeds readily on Chenopodium album, a plant which has been shown to contain levels of ecdysteroid reaching 175 ppm, The significance of these results in relation to the phytoecdysteroid content of the larval host plants of S. littoralis is discussed. Copyright (C) 1996 Elsevier Science Ltd