Ground beetles Temporal range: | |
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Golden ground beetle eating an earthworm in Northern Germany | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Insecta |
Order: | Coleoptera |
Suborder: | Adephaga |
(unranked): | Geadephaga |
Superfamily: | Caraboidea |
Family: | Carabidae Latreille, 1802 |
Subfamilies [1] | |
(See text) |
Ground beetles are a large, cosmopolitan family of beetles, [2] the Carabidae, with more than 40,000 species worldwide, around 2,000 of which are found in North America and 2,700 in Europe. [3] As of 2015, it is one of the 10 most species-rich animal families. They belong to the Adephaga. Members of the family are primarily carnivorous, but some members are herbivorous or omnivorous. [4]
Although their body shapes and coloring vary somewhat, most are shiny black or metallic and have ridged wing covers (elytra). The elytra are fused in some species, particularly the large Carabinae, rendering the beetles unable to fly. The species Mormolyce phyllodes is known as violin beetle due to their peculiarly shaped elytra. All carabids except the quite primitive flanged bombardier beetles (Paussinae) have a groove on their fore leg tibiae bearing a comb of hairs used for cleaning their antennae. [5]
Typical for the ancient beetle suborder Adephaga to which they belong, they have paired pygidial glands in the lower back of the abdomen. These are well developed in ground beetles, and produce noxious or even caustic secretions used to deter would-be predators. In some, commonly known as bombardier beetles, these secretions are mixed with volatile compounds and ejected by a small combustion, producing a loud popping sound and a cloud of hot and acrid gas that can injure small mammals, such as shrews, and is liable to kill invertebrate predators outright.
To humans, getting "bombed" by a bombardier beetle is a decidedly unpleasant experience. [ citation needed ] This ability has evolved independently twice, as it seems, in the flanged bombardier beetles (Paussinae), which are among the most ancient ground beetles, and in the typical bombardier beetles (Brachininae), which are part of a more "modern" lineage. The Anthiini, though, can mechanically squirt their defensive secretions for considerable distances and are able to aim with a startling degree of accuracy; in Afrikaans, they are known as oogpisters ("eye-pissers"). In one of the very few known cases of a vertebrate mimicking an arthropod, juvenile Heliobolus lugubris lizards are similar in color to the aposematic oogpister beetles, and move in a way that makes them look surprisingly similar to the insects at a casual glance. [6]
A folk story claims that Charles Darwin once found himself on the receiving end of a bombardier beetle's attack, based on a passage in his autobiography. [7] [8] Darwin stated in a letter to Leonard Jenyns that a beetle had attacked him on that occasion, but he did not know what kind:
A Cychrus rostratus once squirted into my eye & gave me extreme pain; & I must tell you what happened to me on the banks of the Cam in my early entomological days; under a piece of bark I found two carabi (I forget which) & caught one in each hand, when lo & behold I saw a sacred Panagæus crux major ; I could not bear to give up either of my Carabi, & to lose Panagæus was out of the question, so that in despair I gently seized one of the carabi between my teeth, when to my unspeakable disgust & pain the little inconsiderate beast squirted his acid down my throat & I lost both Carabi & Panagæus! [9]
Common habitats are under the bark of trees, under logs, or among rocks [2] or sand by the edge of ponds and rivers. Most species are carnivorous and actively hunt for any invertebrate prey they can overpower. [2] Some run swiftly to catch their prey; tiger beetles (Cicindelinae) can sustain speeds of 9 km/h (5.6 mph) [10] – in relation to their body length they are among the fastest land animals on Earth. Unlike most Carabidae, which are nocturnal, the tiger beetles are active diurnal hunters and often brightly coloured; they have large eyes and hunt by sight. Ground beetles of the species Promecognathus laevissimus are specialised predators of the cyanide millipede Harpaphe haydeniana , countering the hydrogen cyanide that makes these millipedes poisonous to most carnivores.
As predators of invertebrates, including many pests, most ground beetles are considered beneficial organisms. The caterpillar hunters (Calosoma) are famous for their habit of devouring prey in quantity, eagerly feeding on tussock moth (Lymantriidae) caterpillars, processionary caterpillars (Thaumetopoeidae) and woolly worms (Arctiidae), which, due to their urticating hairs, are avoided by most insectivores. Large numbers of the forest caterpillar hunter (C. sycophanta), native to Europe, were shipped to New England for biological control of the gypsy moth (Lymantria dispar) as early as 1905.
A few species are nuisance pests. Zabrus is one of the few herbivorous ground beetle genera, and on rare occasions Zabrus tenebrioides , for example, occurs abundantly enough to cause some damage to grain crops. [11] Large species, usually the Carabinae, can become a nuisance if present in large numbers, particularly during outdoor activities such as camping; they void their defensive secretions when threatened, and in hiding among provisions, their presence may spoil food. Since ground beetles are generally reluctant or even unable to fly, mechanically blocking their potential routes of entry is usually easy. The use of insecticides specifically for carabid intrusion may lead to unfortunate side effects, such as the release of their secretions, so it generally is not a good idea unless the same applications are intended to exclude ants, parasites or other crawling pests.
Especially in the 19th century and to a lesser extent today, their large size and conspicuous coloration, as well as the odd morphology of some (e.g. the Lebiini), made many ground beetles a popular object of collection and study for professional and amateur coleopterologists. High prices were paid for rare and exotic specimens, and in the early to mid-19th century, a veritable "beetle craze" occurred in England. As mentioned above, Charles Darwin was an ardent collector of beetles when he was about 20 years old, to the extent that he would rather scour the countryside for rare specimens with William Darwin Fox, John Stevens Henslow, and Henry Thompson than to study theology as his father wanted him to do. In his autobiography, he fondly recalled his experiences with Licinus and Panagaeus , and wrote:
No poet ever felt more delight at seeing his first poem published than I did at seeing in Stephen's Illustrations of British Insects the magic words, "captured by C. Darwin, Esq." [8]
The Adephaga are documented since the end of the Permian, about 250 million years ago (Mya). Ground beetles evolved in the latter Triassic, having separated from their closest relatives by 200 Mya. The family diversified throughout the Jurassic, and the more advanced lineages, such as the Harpalinae, underwent a vigorous radiation starting in the Cretaceous. The closest living relatives of the ground beetles are the false ground beetles (Trachypachidae) and the tiger beetles (Cicindelidae). They are sometimes even included in the Carabidae as subfamilies or as tribes incertae sedis , but more preferably they are united with the ground beetles in the superfamily Caraboidea, or Geadephaga. [12]
Much research has been done on elucidating the phylogeny of the ground beetles and adjusting systematics and taxonomy accordingly. While no completely firm consensus exists, a few points are generally accepted: The ground beetles seemingly consist of a number of more basal lineages and the extremely diverse Harpalinae, which contain over half the described species and into which several formerly independent families had to be subsumed. [13]
The taxonomy used here is primarily based on the Catalogue of Life and the Carabcat Database. Other classifications, while generally agreeing with the division into a basal radiation of more primitive lineages and the more advanced group informally called "Carabidae Conjunctae", [14] differ in details. For example, the system used by the Tree of Life Web Project makes little use of subfamilies, listing most tribes as incertae sedis as to subfamily. [15] Fauna Europaea , though, splits rather than lumps the Harpalinae, restricting them to what in the system used here is the tribe Harpalini. [16] The exclusion of Trachypachidae as a separate family is now amply supported, as is the inclusion of Rhysodidae as a subfamily, closely related to Paussinae and Siagoninae. [12]
The exclusive Harpalinae is presented here, because the majority of authors presently use this system, following the Carabidae of the World, Catalogue of Palaearctic Coleoptera, or the Carabcat Database [17] (which is reflected the Catalogue of Life). [18]
Tiger Beetles have historically been treated as a subfamily of Carabidae under the name Cicindelinae, but several studies since 2020 indicated that they should be treated as a family, Cicindelidae, a sister group to Carabidae. [12]
The Adephaga are a suborder of beetles, and with more than 40,000 recorded species in 10 families, the second-largest of the four beetle suborders. Members of this suborder are collectively known as adephagans. The largest family is Carabidae which comprises most of the suborder with over 40,000 species. Adephaga also includes a variety of aquatic beetles, such as predaceous diving beetles and whirligig beetles.
Harpalinae is the largest subfamily of ground beetles, containing more than 19,000 species worldwide.
Zabrus is a genus of ground beetles. They are, unusually for ground beetles, omnivores or even herbivores, and Zabrus tenebrioides can become a pest in cereal fields.
Ant nest beetles or paussines, some members of which are known also as flanged bombardier beetles, are a large subfamily within the ground beetles (Carabidae).The tribes Metriini, Ozaenini, Paussini and Protopaussini are included in the subfamily.
Dryptinae is a subfamily of ground beetles in the family Carabidae. There are more than 30 genera and 570 described species in Dryptinae.
Lebiinae is a subfamily of ground beetles in the family Carabidae. There are more than 330 genera and 6,300 described species in Lebiinae, in 5 tribes.
Licininae is a subfamily of in the beetle family Cicindelidae. There are more than 80 genera and 1,800 described species in Licininae.
Pterostichinae is a subfamily of ground beetles. It belongs to the advanced harpaline assemblage, and if these are circumscribed sensu lato as a single subfamily, Pterostichinae are downranked to a tribe Pterostichini. However, as the former Pterostichitae supertribe of the Harpalinae as loosely circumscribed does seem to constitute a lineage rather distinct from Harpalus, its core group is here considered to be the present subfamily and the Harpalinae are defined more narrowly.
Rhysodinae is a subfamily in the family Carabidae. There are 19 genera and at least 380 described species in Rhysodinae. The group of genera making up Rhysodinae had been treated as the family Rhysodidae in the past, and subsequent DNA analysis then placed it within Carabidae, where it was sometimes treated as the tribe Rhysodini, but the most recent analyses place it as a subfamily in a clade along with subfamilies Paussinae and Siagoninae, forming a sister to the remaining Carabidae.
Scaritinae is a worldwide subfamily of beetles in the family Carabidae, containing more than 2400 species in over 140 genera.
Epomis is a subgenus of ground beetle genus Chlaenius. The larvae of this subgenus are notable for being obligate role-reversal predators. Amphibians such as frogs are normally predators of beetles; however, Epomis larvae feed exclusively on amphibians.
Oodini is a ground beetle tribe in the subfamily Harpalinae. Oodines are found worldwide and are generally associated with standing water. This tribe contains more than 400 species arrayed in 43 genera. Beetles in Oodini are distinguishable from other members of Carabidae by a combination of two characters: a laterally coadunate metepisternum, and an elytral ridge formed by the fusion of intervals 7 and 8.
Harpalini is a tribe of a diverse group of ground beetles belonging to the subfamily Harpalinae within the broader family Carabidae. The tribe contains more than 1,900 species.
Lebiini is a tribe of ground beetles in the family Carabidae. There are more than 250 genera and 4,800 described species in Lebiini.
Pterostichini is a tribe of ground beetles in the subfamily Harpalinae. There are about 180 genera and more than 3,800 described species in Pterostichini.
Zuphiini is a tribe of ground beetles in the family Carabidae, found worldwide.
Panagaeini is a tribe of ground beetles in the family Carabidae. There are more than 20 genera and 300 described species in Panagaeini.
Megacephalini is a tribe of big-headed tiger beetles in the family Cicindelidae.
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