Influence of chorion ingestion on the performance of Ascia monuste and itsassociation with cannibalism

1. In some lepidopterans, the newly hatched caterpillars feed on chorion (a nimal protein) as their first food. This is also a frequent behaviour of ne wly hatched caterpillars of Ascia monuste. 2. According to some parameters tested (time for pupation, number of adults , male imago weight, and fifth-instar ingestion), chorion ingestion by firs t-instar larvae affects adult performance positively. The ingestion of ultr aviolet-sterilised chorion provided the same positive effect on performance . It is thus suggested that young caterpillars may be benefiting from chori on nutritionally, and that chorion ingestion is a chain of events that lead s to positive effects on insect performance. 3. Cannibalism in A. monuste was observed in newly hatched caterpillars and is related to the chorion ingestion behaviour. A condition for this to occ ur was the interval of time of hatching, which means that, if a group of ca terpillars hatches very much before another group, once the caterpillars ha ve ingested the chorion of their own eggs, there is a tendency for them to ingest the chorion of other eggs (including unhatched eggs) and, consequent ly, practice cannibalism. 4. Ascia monuste immatures are considered to be herbivorous, however it is important to know that they eat animal tissue (chorion and conspecific eggs ).