Landcare Research - Manaaki Whenua

Landcare-Research -Manaaki Whenua

FNZ 43 - Carabidae (Insecta: Coleoptera) catalogue - Popular summary

Larochelle, A; Larivière, M-C 2001. Carabidae (Insecta: Coleoptera): catalogue. Fauna of New Zealand 43, 285 pages.
( ISSN 0111-5383 (print), ; no. 43. ISBN 0-478-09342-X (print) ). Published 15 Jun 2001

Popular summary

Ground beetles

The family Carabidae (ground beetles, including tiger beetles) is composed of 25 000 to 50 000 species worldwide, but probably at least twice as many taxa remain to be described. The world fauna is divided into 6 subfamilies and 85 tribes. Compared with larger or warmer regions of the world, the New Zealand fauna may appear relatively small (5 subfamilies, 20 tribes, 78 genera, 424 species), but New Zealand, with Australia, is a special place where the tribes Amarotypini, Broscini, Mecyclothoracini, Meonini, Migadopini, Pamborini, Tropopterini, and Zolini appear to have achieved their greatest taxonomic diversity. Once described, the New Zealand fauna will likely reach 600 species. Endemism is high with 92% (391) of species and 58% (46) of genera currently recognised as occurring only in this country. Faunal affinities are greatest with eastern Australia (16 native genera and 4 native species are shared).

While it is easy to recognise a carabid as such, it is rather difficult to identify it at the species level. Ground beetles show a relatively high degree of morphological uniformity, a marked diversity of taxa, and striking ecological preferences, which make them especially suitable for studying the ecological and physical adaptations required to cope with environmental demands. Carabids are generally abundant and demonstrate a flexible set of responses to environmental factors. Because of these features, the relative ease with which their populations may be sampled by reliable quantitative methods (e.g., pittrapping), and their potential use as bioindicators and biocontrol agents, these beetles increasingly attract the attention of world scientists. Biologists investigating evolutionary and ecological hypotheses particularly favour this group. In New Zealand, conservation biologists have already listed many, often large-sized carabid species, as rare or threatened and worthy of protection.

As a result, ground beetles are among the best represented insect groups in New Zealand entomological museums and collections. But despite such high interest, no catalogue or checklist has been produced since 1934, although numerous name changes and new species have been published since then.

In general, carabids are hygrophilous (moisture-loving) species living at ground surface, but a number of species also live deep in the soil, in caves, or on plants and trees, and several species occur in association with the loose bark of trees or in rotten branches. The two New Zealand native habitats that harbour the greatest number of species are forests and tussock grasslands. While some species live almost exclusively along coastal lowlands, the majority of New Zealand species are found from the lowlands to higher elevations below the subalpine zone. Very few described carabids appear to be restricted to subalpine or alpine environments, but many new species remain to be described from such habitats. Most indigenous carabids occur naturally within the confines of native habitats, although a number of them can survive in modified environments. About 10 adventive species live around human dwellings. About 50 species (mostly native) dwell successfully in pine plantations, provided these are located near or adjacent to native forests. Introduced species seem to be able to invade natural habitats, but only to a slight degree.

Very little is known about the life history of native Carabidae. The reproductive season of most species is unknown. Population biology and locomotion are virtually undocumented. Mouthpart morphology and food data suggest that most species are opportunistic predators eating on a variety of small prey. Adults are active during most of the year, a little less so in winter. Adults are generally nocturnal. Parental care, or protection of eggs and larvae by the female, has been observed in 11 species. Larvae are usually very secretive, living in ground burrows or holes, and are rarely encountered at the surface of the ground, which makes them difficult to sample either by hand or by trapping.

New Zealand ground beetles have a number of enemies and parasites. Starlings, kiwis, spiders, and hedgehogs are frequent predators, while magpies, asilids, kingfishers, fernbirds, stoats, feral cats, thrushes, trout, and rats appear to be occasional predators. Based on the authors' field experience, spiders could be significant predators, especially in tussock grasslands, herbfields, and fellfields. About 32% (137 species) of all carabid species studied are infested by mites (Acari), and at least 11% (48 species) of the total carabid fauna are subjected to infestations by fungi (Laboulbeniales). Species infested with Laboulbeniales or mites are usually rain-forest dwellers, often associated with rotten wood, branches, or logs. Nematodes have been found to parasitise 5 ground- beetle species.

Carabids with fully developed wings disperse easily and can form stable populations soon after colonising new environments. However, the majority of native ground beetles are flightless and use running as their main means of locomotion. When disturbed, Carabidae generally burrow into litter or soil, or run away. A number of other interesting defense mechanisms can be observed in New Zealand species. Two tiger beetles use a form of camouflage or colour pattern, blending perfectly with the background, to protect themselves against enemies. Death feigning can be observed in several species, mostly in the tribe Broscini. Other species emit a repulsive smell or bite strongly when seized. Adults of Amarotypus standing on tree trunks at night drop to the ground if approached too closely, and Prosphrodrus species have the peculiar habit of diving into water when disturbed.

Too little information is currently available on the abundance and distribution of supposedly rare species to establish their conservation status with certainty, even though about 50 taxa have been declared as such. It is only through investigations including quantitative trapping and mark-recapture over several seasons that any meaningful conservation assessment can be formulated. Ground beetles are usually well hidden and scattered by day, hence usually escape the attention of the most specialised or attentive collector. Having to rely on casual observations or collection prevents any realistic approxim-ation of population size and distribution.

Information about New Zealand carabids accumulated over the last 150 years is not easily accessible. It is most often scattered through the world literature or still associated with specimens in biological collections. With this catalogue, the authors wish to provide specialist as well as non-specialist readers with a compendium of all available knowledge on the taxonomy, distribution, ecology, biology, and dispersal of Carabidae. The format of the catalogue has been developed with the interests of systematists and other biologists in mind. It allows easy information retrieval, comparison between taxa, and synthesis of data. The authors believe that such a comprehensive database is necessary before testing hypotheses about environmental relationships in Carabidae.