Aposematic and cryptic Lepidoptera tested on the mouse

Abstract

The toxicity of 53 species of Lepidoptera which are aposematic (a) at all stages of development; (b) as larvae but not as adults; (c) as adults but not as larvae, is compared with that of cryptic species, by means of a qualitative test consisting of intraperitoneal injection into the laboratory mouse. Points of interest which emerged from this study include (i) Pieris brassicae is toxic whether or not the larval diet contains sinigrin and mustard oils; (ii) a marked sexual dimorphism in toxicity is noted in several species; (iii) a yellow (recessive) variety of Callimorpha dominula (ab. lutea ) is less toxic than the typical form; (iv) P. brassicae pupae are acceptable to certain birds if the larvae are reared on artificial diet, but rejected (on account of taste or smell) if fed on cabbage; (v) only Arctia caja , out of 14 species tested, retains its toxicity when dried, and (vi) the gravid female Zygaena trifolii and her eggs kill the mouse in two to three minutes.