THE EFFECTS OF INGESTED 20-HYDROXYECDYSONE ON THE LARVAE OF AGLAIS-URTICAE, INACHIS-IO, CYNTHIA-CARDUI (LEPIDOPTERA, NYMPHALIDAE) AND TYRIA-JACOBAEAE (LEPIDOPTERA, ARCTIIDAE)

A comparative survey was carried out to investigate the effects, distr ibution and metabolism of ingested 20-hydroxyecdysone in four species of lepidopteran larvae in relation to the phytoecdysteroid content of the insect's host plants, Analysis of the leaves of the host plants of each of the species revealed a strong relationship between the levels of phytoecdysteroids and the relative tolerance of the Larvae to inge sted 20-hydroxyecdysone. Monophagous or oligophagous species (Aglais u rticae, Inachis io) feeding on ecdysteroid-negative host plants were e ither deterred from feeding or showed marked abnormalities in growth a nd development after incorporation of 20-hydroxyecdysone in their diet s, Oligophagous or polyphagous species (Tyria jacobaeae, Cynthia cardu i) which feed on host plants from families which are known to contain phytoecdysteroid-positive species, were able to tolerate low levels of 20-hydroxyecdysone in their diets, but exhibited developmental defect s at high concentrations, These species were termed semi-tolerant, In each of the species, ingested [H-3]20-hydroxyecdysone appeared to foll ow the same fate as injected [H-3]20-hydroxyecdysone. The data are com pared to those obtained in previous studies, where truly polyphagous s pecies were shown to tolerate very high concentrations of 20-hydroxyec dysone in their diets by the production of ecdysteroid 22-fatty acyl e sters. (C) 1997 Elsevier Science Ltd.