Ant nest beetles (

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...

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 distribution, cosmopolitan family (biology), 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 ...

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 file:Panaphis juglandis.jpg , thumb , Myrmecophilous aphids being tended by ants Myrmecophily ( , ) consists of positive, Mutualism (biology), mutualistic, interspecies Association (ecology), associations between ants and a variety of other or ...

s, living within the nests of ants, predatory on

ant Ants are Eusociality, eusocial insects of the Family (biology), family Formicidae and, along with the related wasps and bees, belong to the Taxonomy (biology), order Hymenoptera. Ants evolved from Vespoidea, vespoid wasp ancestors in the Cre ...

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e and workers. Many have elaborate antennal structures and body parts flattened. Paussines are moderate sized (6–20 mm), characterised by

gland A gland is a Cell (biology), cell or an Organ (biology), organ in an animal's body that produces and secretes different substances that the organism needs, either into the bloodstream or into a body cavity or outer surface. A gland may also funct ...

ular hairs that produce secretions attractive to ants and by the odd antennal structures of many

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

. Their pygidial glands can produce

explosive An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An ex ...

secretions, with a spray of

quinone The quinones are a class of organic compounds that are formally "derived from aromatic compounds benzene.html" ;"title="uch as benzene">uch as benzene or naphthalene] by conversion of an even number of –CH= groups into –C(=O)– groups with ...

s that are directed forward by flanges at the posterior end of the

elytra An elytron (; ; : elytra, ) 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 (sometime ...

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

bombardier beetle Bombardier beetles are adephagan ground beetles (Carabidae) in the tribes Brachinini, Paussini, Ozaenini, or Metriini—more than 500 species altogether—which are most notable for the defense mechanism that gives them their name: when disturbe ...

s (

Brachininae Brachininae is a subfamily of beetles in the family Carabidae. There are about 7,500 species in 14 genera of the subfamily. Taxonomy The subfamily contains two tribes and 14 genera. ; Tribe Brachinini Bonelli, 1810 : '' Aptinoderus'' Hubenthal, ...

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 (biology), 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 ...

, 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 comp ...

'' 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 Coandă effect ( or ) is the tendency of a jet (fluid), fluid jet to stay attached to a surface of any form. ''Merriam-Webster'' describes it as "the tendency of a jet of fluid emerging from an orifice to follow an adjacent flat or curved s ...

. 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 Metriini is a tribe of ground beetles in the family Carabidae. There are at least three genera and about six described species in Metriini. Genera These genera belong to the tribe Metriini: * '' Metrius'' Eschscholtz, 1829 (2 species, found in ...

LeConte, 1853 : Subtribe †Kryzhanovskianina Deuve, 2019 ;

Ozaenini Ozaenini is a tribe of ground 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 ...

Hope, 1838 : Subtribe Microzaenina Deuve, 2019 : Subtribe Mystropomina G.Horn, 1881 : Subtribe Ozaenina Hope, 1838 : Subtribe Pseudozaenina Sloane, 1905 ;

Paussini Paussini is a tribe of ground beetles in the family Carabidae. There are more than 25 genera and 610 described species in Paussini. They are found mainly in Africa, southern Asia, and the Pacific, although the genus ''Homopterus'' is found in the ...

Latreille, 1806 : Subtribe Carabidomemnina Wasmann, 1928 : Subtribe Cerapterina Billberg, 1820 : Subtribe Heteropaussina Janssens, 1950 : Subtribe Homopterina Wasmann, 1920 : Subtribe Paussina Latreille, 1806 : Subtribe Pentaplatarthrina Jeannel, 1946 : Subtribe †Arthropteritina Luna de Carvalho, 1961 : Subtribe †Eopaussina Luna de Carvalho, 1951 ;

Protopaussini ''Protopaussus'' is a genus of ground beetles in the family Carabidae, the sole genus of the tribe Protopaussini. It is found in Indomalaya and temperate Asia. Species These nine species belong to the genus ''Protopaussus'': * '' Protopaussus al ...

Gestro, 1892

References

{{DEFAULTSORT:Ant Nest Beetle Paussinae