Defenses in leaf beetles

1. Fecal shields.

Larva with black fecal shield (photo: Kenji Nishida)
Larva with black fecal shield (photo: Kenji Nishida)

When attacked, adult beetles can fly off or drop to the undergrowth.  Baby beetles can only walk away
or hunker down.  Five subfamilies of leaf beetles have larvae with a highly unusual defense–they recycle their feces and exuviae (“cast skins”) into defense structures. These can take the form of an armor worn
directly on the body (in Criocerinae and some flea beetles), like a top-hat (Cryptocephalinae and Lamprosomatinae), or carried like an umbrella above the body (Cassidine tortoise beetles).  Feces and old skins may be a nasty barrier for an enemy insect to circumvent, but it can be made nastier with offensive chemicals from the host plant or manufactured by the larva.  See my interview in
Wired Magazine: http://www.wired.com/2015/06/absurd-creature-of-the-week-tortoise-beetle/

2. Maternal care (subsociality)

Pterodunga female tending her larvae in Australia (Photo: S. Hasenpusch)
Pterodunga female tending her larvae in Australia (Photo: S. Hasenpusch)

The great insect societies of ants, bees, and termites are well-known. However, many other insects show interesting behaviors for the guarding and rearing of their young. At least 11 families of beetles exhibit subsocial species, where one or both parents care for broods of larvae. Dung beetles come easily to mind. Leaf beetles range greatly in the amount of care they provide to their young—no care, some effort for protection of eggs, or further investment in guarding the brood. Some leaf beetles are even viviparous, giving birth to live larvae. Two subfamilies, Cassidinae and Chrysomelinae, have subsocial species and I am interested in the evolution of this behavior.  Read my interview here: http://news.ku.edu/2014/06/09/research-shows-usually-solitary-leaf-beetles-can-act-helicopter-moms

Collaborators: Fernando Frieiro-Costa/Centro Universitário de Lavras–Unilavras-Brazil; Jesús Gómez-Zurita/CSIC-Spain; Ken Keefover-Ring/U. Wisconsin-Madison, Alexandra (“Alex”) Trillo/ Gettysburg College; Fred V. Vencl/Stony Brook U.; and Rob Westerduijn/Peru.

Funding: We are currently funded by NSF-EAGER 1547851  to integrate chemical, experimental, and phylogenetic approaches to elucidate the origin and diversification of leaf beetle defenses and subsociality.

Recommended general readings: Costa J. 2006. The other insect societies. Harvard: Belknap, 767 p.

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