Leaf beetles, seed weevils, flea beetles (Alticini)

Code QCAH9999

A family of Polyphaga - the large suborder of beetles in which the prothoracic pleuron is entirely concealed and the hind coxae are motile.

This is a very large family of leaf- and seed-eating beetles, the vast majority of which are terrestrial. A relatively small number of species are associated with water plants and some of these feed at some part of the life cycle on submerged parts of the plant.

The family as a whole is morphologically very variable, encompassing a wide range of body forms. How much of this variation occurs in aquatic and semi-aquatic species is unclear.

Identification is most simply done on the basis of tarsal characters. Chrysomeloidea and Curculionoidea are characterised by having pseudo-tetramerous tarsi: that is, there are five tarsal segments but the fourth is minute and is hidden by expanded side-lobes of the third. The remaining tarsal segments may be cylindrical or swollen, or may end in flattened and/or setose lobes or in a setose pad.

No aquatic families other than Chrysomelidae and the two weevil families, Curculionidae and Brentidae, have such tarsal development. Separation of the weevils from Chrysomelidae is readily achieved on the basis of elongate rostrate head and elbowed antennae (most Curculionidae, some Brentidae) or fusion of the first two visible abdominal sternites to form a more or less rigid hind-body (some Chrysomelidae, Curculionidae, Brentidae including those in which the antennae are not elbowed).

Two main groups of Chrysomelidae (Polyphaga: Chrysomeloidea) have larvae with aquatic affiliations, and as such adults of these groups may occur in aquatic samples. Larval Donacia attaches by respiratory horns to submerged stems or roots of waterlily and other aquatic plants, tapping the stems for air while grazing on vascular plant material. Larval Alticini may be found mining the stems or leaves of aquatic plants. Two species of Donacia occur in north Queensland and the Northern Territory. Alticini (flea beetles) are more diverse and widespread. Overall, around 3000 Chrysomelidae species occur in Australia.

Reference:

Lawrence, J.F. and Britton, E.B. (1991) Coleoptera. pp. 543-683. In: CSIRO, Insects of Australia. Volume 2. Melbourne University Press, Carlton, Victoria.