Coleoptera

Fikáček, Martin, Skuhrovec, Jiří, Šípek, Petr & Fikáček, for abstracts see, 2011, Abstracts of the Immature Beetles Meeting 2011, Acta Entomologica Musei Nationalis Pragae 51 (2), pp. 731-756 : 747-748

Larvae of case-bearing leaf beetles ( Coleoptera : Chrysomelidae : Cryptocephalinae)

Matthias SCHÖLLER

Biological Consultancy Ltd., Storkower Str. 55, 10409 Berlin, Germany; e-mail: [e-mail]

The larvae of leaf beetles in the subfamilies Lamprosomatinae and Cryptocephalinae with its three tribes Clytrini , Cryptocephalini and Chlamisini wear a case, for this reason they are called ‘case bearers’. This case is based on an extrachorion produced by the parental females which cover their eggs with a case made by faeces and secretes. The egg case is subsequently kept and enlarged by the larva with faeces and soil as they grow. Pupation takes place within the larval case (ERBER 1988).

On a world-wide scale, the larvae of about 6 % of the Cryptocephalinae were described, however, the quality of the descriptions is quite variable because the descriptions partly date back to the 19 th century. The knowledge of the Central European fauna is much better, mostly due to the publications of W. Steinhausen (e.g., STEINHAUSEN 2007), the keys allow to determine approximately 90 % of the species.

Larval characters used for determination include the shape and microsculpture of the head capsule, the stigmal plates, and setae of the tibiotarsus and the head capsule. While late-instar larvae are needed for determination, first instar larvae provide characters of importance for phylogenetic studies like spatulate and papillate head capsule setae (REID 1995).

The larvae of most Cryptocephalinae feed on leaf litter contrary to the adults that feed on green parts of the plants. Consequently the subfamily is well represented in semi-desert and steppe biotopes, where green leaves may not be present all year round. However, there are also many Cryptocephalinae present in tropical rainforests.

The larval cases provide some protection from generalist insect predators, but parasitoid natural enemies are known (SCHÖLLER 1999), and Carabid beetles and mammalian insectivores have been shown to prey on Cryptocephalinae larvae (OWEN 2003).

Several species in the tribe Clytrini and few in the tribe Cryptocephalini are known to be associated with ants. The larvae of these myrmecophilous species were collected in the vicinity or even within the nest of ants. However, the life-history of these species is only poorly known and controversial information can be found in the literature, ranging from nest materials as feeding substrate to predatory behaviour. In one study, the Clytrini Macrolenes dentipes (Olivier) was experimentally shown to feed on both dry and fresh insect fragments (zoosaprophagy) as well as leaf litter (phytosaprophagy) (SCHÖLLER 1998). Recently another species, Clytra laeviuscula Ratzeburg , was shown to be zoosaprophagous (Schöller, unpubl. data). The larvae are presumably actively transported into the nest by the ants. Foraging Lasius emarginatus (Olivier) ants were experimentally offered eggs and first instar larvae of C. laeviuscula . First instar larvae were instantly picked up and transported by the worker ants, while eggs were only picked up in 30 % of the observations (Schöller, unpubl.).

The future study of larvae of especially tropical Cryptocephalinae is a promising field for both research on phylogeny and life-history of this species-rich leaf beetle subfamily.

ERBER D. 1988: Biology of Camptosomata Clytrinae – Cryptocephalinae – Clamisinae – Lamprosomatinae. Pp. 513–552.In: JOLIVET P., PETITPIERRE E. & HSIAO T. H.(eds.): Biology of Chrysomelidae . Kluwer Academic Publishers, Dordrecht, the Netherlands.

OWEN J. A. 2003: Field studies on Cryptocephalus coryli (Linnaeus) ( Coleoptera : Chrysomelidae ). Entomologist’s Gazette 54: 39–44.

SCHÖLLER M. 1998: Zoosaprophagy and phytosaprophagy in chrysomelid beetle larvae, Macrolenes dentipes and Pachybrachis anoguttatus ( Coleoptera : Chrysomelidae : Clytrinae and Cryptocephalinae). Museo Regionale di Scienze Naturali Bollettino (Torino) 1998: 281–285.

SCHÖLLER M. 1999: Field studies of Cryptocephalinae biology. Pp. 421–436. In: COX M. L. (ed.): Advances in Chrysomelidae biology 1. Backhuys Publishers, Leiden, the Netherlands.

STEINHAUSEN W. 2007: Die Blattkäfergattung Cryptocephalus Geoffroy (1768) und ihre Untergattungen in Mitteleuropa nach larvaler Morphologie mit einer Revision der Larven-Bestimmungstabelle (Steinhausen, 1994). Mitteilungen der Münchner Entomologische Gesellschaft 97: 23–32.

REID C. A. M. 1995: A cladistic analysis of subfamilial relationships in the Chrysomelidae sensu lato (Chrysomeloidea). Pp. 559–631. In: PAKALUK J. & SLIPINSKI S. A. (eds.): Biology, phylogeny, and classification of Coleoptera . PAN, Warzawa.