Scientific Note: Caterpillar mimicry across orders: Pine sawfly larvae as a possible model for an Erythrina Leafroller caterpillar, Agathodes monstralis (Lepidoptera, Crambidae)

Abstract

While caterpillars are under huge selective pressure from predators and are frequently chemically protected, very few cases of caterpillar mimicry have been formally described in the scientific literature compared to the mimicry complexes found in adult Lepidoptera. Nevertheless, caterpillar mimicry may be common, so possible mimicry complexes should be described and, when possible, investigated. Here, it is proposed that caterpillars of the Redheaded Pine Sawfly, Neodiprion lecontei (Hymenoptera, Diprionidae), are chemically defended co-mimics with a crambid caterpillar, Agathodes monstralis (Lepidoptera, Crambidae), with which they are found in the same habitat in eastern United States. While both species are chemically defended, based on differences in behavior (open gregarious feeding for the sawfly larvae and concealed solitary feeding in the moth caterpillar), this mimicry complex is likely to be quasi-Batesian (both contribute to aposematic signal, albeit unequally). This mimicry hypothesis is supported by the strong phenotypic similarity between the larvae of the two insect taxa discussed here, and the obvious divergence in Agathodes monstralis in comparison with congeners outside the sawfly’s range.