Ant nest beetles ( subfamily Paussinae) or paussines, some members of which are known also as flanged bombardier beetles, are a large subfamily within the

ground beetle Ground beetles are a large, cosmopolitan family of beetles, the Carabidae, with more than 40,000 species worldwide, around 2,000 of which are found in North America and 2,700 in Europe. As of 2015, it is one of the 10 most species-rich animal f ...

s (Carabidae).The tribes Metriini, Ozaenini, Paussini and Protopaussini are included in the subfamily. Rarely seen in the open, except at lights, most Paussinae are obligate or facultative

myrmecophile Myrmecophily ( , ) is the term applied to positive interspecies associations between ants and a variety of other organisms, such as plants, other arthropods, and fungi. Myrmecophily refers to mutualistic associations with ants, though in its m ...

s, living within the nests of ants, predatory on

ant Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of ...

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

e and

workers The workforce or labour force is a concept referring to the pool of human beings either in employment or in unemployment. It is generally used to describe those working for a single company or industry, but can also apply to a geographic reg ...

. Many have elaborate antennal structures and body parts flattened. Paussines are moderate sized (6–20 mm), characterised by glandular hairs that produce secretions attractive to ants and by the odd antennal structures of many

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

. Their pygidial glands can produce explosive secretions, with a spray of quinones that are directed forward by flanges at the posterior end of the

elytra An elytron (; ; , ) is a modified, hardened forewing of beetles (Coleoptera), though a few of the true bugs (Hemiptera) such as the family Schizopteridae are extremely similar; in true bugs, the forewings are called hemelytra (sometimes alterna ...

, giving them the other name of flanged bombardier beetles although they are not particularly close relatives of the typical bombardier beetles (

Brachininae Brachininae is a subfamily of beetles in the family Carabidae Ground beetles are a large, cosmopolitan family of beetles, the Carabidae, with more than 40,000 species worldwide, around 2,000 of which are found in North America and 2,700 in Europ ...

Biology

Very little is known about the immature stages of ant nest beetles. Most appear to live in ant nests in their early stages of life. Although many are facultative or obligate myrmecophiles, most do not appear like ants (i.e. myrmecomorphic) and unlike in the case of myrmecophilous larval

Lycaenidae Lycaenidae is the second-largest family of butterflies (behind Nymphalidae, brush-footed butterflies), with over 6,000 species worldwide, whose members are also called gossamer-winged butterflies. They constitute about 30% of the known butterf ...

, there appears to be no benefit gained by the ants in this association. Many species follow the trails of worker ants of specific species. Glandular secretions on their antennae and body allow them to interact with ant workers. It is believed that the beetles use an acoustic mechanism to successfully imitate the sounds of an ant queen thus permitting them access to the nest without alarming the ants. Worker ants groom the beetles. Adult ''Paussus favieri'' have been observed to antennate and interact by

stridulation Stridulation is the act of producing sound by rubbing together certain body parts. This behavior is mostly associated with insects, but other animals are known to do this as well, such as a number of species of fish, snakes and spiders. The mech ...

with the queen of ''

Pheidole pallidula ''Pheidole pallidula'' is a species of ant in the genus ''Pheidole''. It is widespread around the Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enc ...

'' in the brood chamber. The defensive bombardier behaviour is never used against ants. Unlike bombardier beetles in the family Brachininae, which have two glands opening close together on the abdomen, the glands are located close to the lateral margins and lie under a flange formed by the tip of the elytra. The flange is curved and the explosive hot spray of quinones is directed forward by Coandă effect. The flange is not present in members of the tribe Metriini but is replaced by similar internal structures. Males of some species are attracted to lights during some parts of the season and are thought to disperse from one ant nest to another. Males are thought to be short-lived. These beetles feed on ant eggs, larvae and adults by piercing their mandibles into the abdomen or other soft part and sucking the contents. Apart from chemical mimicry and communication with their hosts, they also make use of vibrations. Several stridulatory structures are found in these beetles including alary-elytral, abdomen-femur and thorax-femur combinations of surfaces. Larvae of only about 10 species have ever been examined. The first instar larvae of ''Paussus favieri'' has a terminal disc which is raised at times and bent back over the head. They also exhibit some behaviours and mouth part adaptations which may be involved in eliciting trophallaxis by the ant hosts but this has not been confirmed. They opportunistically feed on the haemolymph of ant larvae.

Systematics

The subfamily Paussinae contains 54 genera, with over 800 species divided into the following tribes and subtribes: While some tribes like Metriini and Ozaenini appear quite similar to typical carabids, others have modified antennae and body shapes. The Protopaussini and Paussini are slender or compact in body shape with enlarged antennae in the Paussini. Arthropterus cerapteroides

These four tribes belong to the subfamily Paussinae: ; Metriini LeConte, 1853 : Subtribe †Kryzhanovskianina Deuve, 2019 ; Ozaenini Hope, 1838 : Subtribe Microzaenina Deuve, 2019 : Subtribe Mystropomina G.Horn, 1881 : Subtribe Ozaenina Hope, 1838 : Subtribe Pseudozaenina Sloane, 1905 ; Paussini Latreille, 1806 : Subtribe CarabidomemninaWasmann, 1928 : Subtribe CerapterinaBillberg, 1820 : Subtribe HeteropaussinaJanssens, 1950 : Subtribe HomopterinaWasmann, 1920 : Subtribe PaussinaLatreille, 1806 : Subtribe PentaplatarthrinaJeannel, 1946 : Subtribe †ArthropteritinaLuna de Carvalho, 1961 : Subtribe †EopaussinaLuna de Carvalho, 1951 ; Protopaussini Gestro, 1892

References

{{DEFAULTSORT:Ant Nest Beetle Paussinae