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

Summary 1. In some lepidopterans, the newly hatched caterpillars feed on chorion (animal protein) as their first food. This is also a frequent behaviour of newly 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 first‐instar larvae affects adult performance positively. The ingestion of ultraviolet‐sterilised chorion provided the same positive effect on performance. It is thus suggested that young caterpillars may be benefiting from chorion nutritionally, and that chorion ingestion is a chain of events that leads 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 occur was the interval of time of hatching, which means that, if a group of caterpillars hatches very much before another group, once the caterpillars have ingested the chorion of their own eggs, there is a tendency for them to ingest the chorion of other eggs (including unhatched eggs) and, consequently, 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).