Evolution and losses of spines in slug caterpillars (Lepidoptera: Limacodidae)

Abstract

Larvae of the cosmopolitan family Limacodidae, commonly known as “slug” caterpillars, are well known because of the widespread occurrence of spines with urticating properties, a morpho‐chemical adaptive trait that has been demonstrated to protect the larvae from natural enemies. However, while most species are armed with rows of spines (“nettle” caterpillars), slug caterpillars are morphologically diverse with some species lacking spines and thus are nonstinging. It has been demonstrated that the evolution of spines in slug caterpillars may have a single origin and that this trait is possibly derived from nonstinging slug caterpillars, but these conclusions were based on limited sampling of mainly New World taxa; thus, the evolution of spines and other traits within the family remains unresolved. Here, we analyze morphological variation in slug caterpillars within an evolutionary framework to determine character evolution of spines with samples from Asia, Australia, North America, and South America. The phylogeny of the Limacodidae was reconstructed based on a multigene dataset comprising five molecular markers (5.6 Kbp: COI, 28S, 18S, EF‐1α, and wingless) representing 45 species from 40 genera and eight outgroups. Based on this phylogeny, we infer that limacodids evolved from a common ancestor in which the larval type possessed spines, and then slug caterpillars without spines evolved independently multiple times in different continents. While larvae with spines are well adapted to avoiding generalist predators, our results imply that larvae without spines may be suited to different ecological niches. Systematic relationships of our dataset indicate six major lineages, several of which have not previously been identified.

Production, composition, and mode of action of the painful defensive venom produced by a limacodid caterpillar, Doratifera vulnerans

“…Our data are consistent with previous reports that ascribe venom secretion in Limacodidae and Megalopygidae to the large cell at the base of each spine (61,64). This observation is consistent with the descent of diverse venomous zygaenoids from a shared venomous ancestor with subsequent loss of venom use in some groups (12). However, we cannot rule out that venom use evolved multiple times in Zygaenoidea, possibly from similar molecular and anatomical precursors.…”

“…Envenomations by limacodids typically induce intense pain, itch, and erythema, and sometimes numbness, weakness, nausea, and dizziness (11). Venom use may have evolved within Limacodidae (10) or in a shared ancestor of Limacodidae and Megalopygidae with subsequent losses in related taxa (12). Limacodid venom has been shown to protect caterpillars against invertebrate predators, and this protection is stronger for predators previously exposed to the venom, indicating that envenomation induces learned avoidance in some predators (13).…”

Larvae of grassland caterpillar endemic to Qinghai–Tibet Plateau (Lepidoptera: Lymantriinae: Gynaephora): identification, distribution, and ultramorphology

“…In Lepidoptera, setae are primarily seen on the head and trunk of the caterpillar 31 . The setae usually specialized into stinging spines in Limacodidae 32 or assembled as dense tufts as mimicry of some Arctiidae, Lasiocampidae, and Lymantriidae 33 . The larvae of G. menyuanensis are covered by large hair tufts, which carry many setae.…”

“Lepidoptera Flies”, but Not Always…Interactions of Caterpillars and Chrysalis with Soil

“…Agathiphagidae [39], Heterobathmiidae [40], Prototheoridae [44], Andesianidae [49], Incurvariidae [54,55], Nematopogoninae [56], Adelidae [136], Heliozelidae [57], Tischeriidae [58], Palaephatidae [59], Psychidae [140], Yponomeutidae [60], Urodidae [72], Douglasiidae [73,160], Schreckensteiniidae [64], Choreutidae [65], Millieriidae [66], Immidae [67], Tortricidae [68][69][70], Heliocosmidae [71], Galacticidae [72,73], Zygaenoids [74,76], Lacturidae [77], Himantopteridae [78,79], Aididae [80], Megalopygidae [81,82], Limacodidae [83,84], Dalceridae [81,85], Cyclotornidae [86,87], Sesiidae [86,142], Dudgeoneidae [86], Cossidae [88,89], Cossulinae [90], Brachodidae…”