''Colobopsis saundersi'' (synonym ''Camponotus saundersi''), also called the Malaysian exploding ant or suicide ant, is a

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), ...

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 ...

found in

Malaysia Malaysia is a country in Southeast Asia. Featuring the Tanjung Piai, southernmost point of continental Eurasia, it is a federation, federal constitutional monarchy consisting of States and federal territories of Malaysia, 13 states and thre ...

and

Brunei Brunei, officially Brunei Darussalam, is a country in Southeast Asia, situated on the northern coast of the island of Borneo. Apart from its coastline on the South China Sea, it is completely surrounded by the Malaysian state of Sarawak, with ...

, belonging to the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

Colobopsis ''Colobopsis'' is a genus of ants in the subfamily Formicinae. This genus was first described in 1861 by Mayr and contains 95 species. The type species is ''Colobopsis truncata''. Description As part of Camponotini, ''Colobopsis'' workers have ...

''. A worker can explode suicidally and aggressively as an ultimate act of defense, an ability it has in common with several other species in this genus and a few other

insects Insects (from Latin ') are hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of jointed ...

. The ant has an enormously enlarged

mandibular In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

gland, many times the size of other ants, which produces adhesive secretions for defense. According to a 2018 study, this species forms a

species complex In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

and is probably related to '' C. explodens'', which is part of the '' C. cylindrica'' group.

Defenses

Its defensive behaviours include self-destruction by

autothysis Autothysis (from the Greek roots ''autos-'' "self" and ''thysia'' "sacrifice") or suicidal altruism is the process where an animal destroys itself via an internal rupturing or explosion of an organ which ruptures the skin. The term was proposed b ...

, a term coined by Maschwitz and Maschwitz (1974). Two oversized, poison-filled

glands run the entire length of the ant's body. When combat takes a turn for the worse, the worker ant violently contracts its abdominal muscles to rupture its gaster at the intersegmental fold, which also bursts the mandibular glands, thereby spraying a sticky secretion in all directions from the

anterior Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

region of its head. The glue, which also has corrosive properties and functions as a chemical irritant, can entangle and immobilize all nearby victims. Direct observation by Jones (2004) found that ''C. saundersi'' adhesive secretions range from bright white at the end of the wet season to cream or pale yellow in the dry season and start of the wet season. These variations in coloration represent a shift in internal pH, likely due to seasonal changes in diet.

Territorial defense

Autothysis in ''C. saundersi'' is common during territorial battles with other ant species or groups. Territorial weaver ants (''Oecophylla smaragdina'') are known to stalk and attack ''C. saundersi'' for territory as well as for predation. Self-sacrifice of ''C. saundersi'' workers is likely to help the colony as a whole by ensuring that the colony retains its foraging territory. Therefore, such behavior would continue within a population given that the behavior was already genetically present within the majority of workers.

Defense against predation

''C. saundersi'' uses autothysis to defend against predation by other

arboreal Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally (scansorial), but others are exclusively arboreal. The hab ...

arthropods (weaver ants, spiders), which are believed to be the main predatory threat to ''C. saundersi'' for two reasons: * Jones (2004) noted through direct observation that ''C. saundersi'' is "remarkably sensitive" to even slight leaf vibration. * The inherent adhesive qualities of ''C. saundersi''s secretion are more effective in immobilizing the

appendages An appendage (or outgrowth) is an external body part or natural prolongation that protrudes from an organism's body such as an arm or a leg. Protrusions from single-celled bacteria and archaea are known as cell-surface appendages or surface app ...

of arthropods as opposed to those of vertebrates. ''C. saundersi'' also uses autothysis to defend against vertebrate predators because the chemicals involved are inedible, which could deter certain predators from engaging this species of ant in the future.

Chemicals

The "toxic glue" of ''C. saundersi'' is predominately composed of polyacetates, aliphatic hydrocarbons, and alcohols. Branched-skeleton lactones and methylated isocoumarins produced in the hindgut function as trail pheromones, while straight-chain hydrocarbons and esters produced in the Dufour's glands act as alarm pheromones in ''C. saundersi'' and related species. Jones, et al. (2004) identified the following chemicals within the secretion:

Phenols In organic chemistry, phenols, sometimes called phenolics, are a class of chemical compounds consisting of one or more hydroxyl groups (− O H) bonded directly to an aromatic hydrocarbon group. The simplest is phenol, . Phenolic compounds ar ...

m-cresol ''meta''-Cresol, also 3-methylphenol, is an organic compound with the formula CH3C6H4(OH). It is a colourless, viscous liquid that is used as an intermediate in the production of other chemicals. It is a derivative of phenol and is an isomer of ...

(traces found), a corrosive compound * 2,4-Dihydroxyacetophenone * 2-Methyl-5,7-dihydroxychromone * Orcinol (traces found) Aliphatics *

Undecane Undecane (also known as hendecane) is a liquid alkane hydrocarbon with the chemical formula CH3(CH2)9CH3. It is used as a mild sex attractant for various types of moths and cockroaches, and an alert signal for a variety of ants. It has 159 isomer ...

2-Heptanone 2-Heptanone, also known as methyl ''n''-amyl ketone, or Heptan-2-one, is a ketone with the molecular formula C7H14O. It is a colorless, water-like liquid with a banana-like, fruity odor. 2-Heptanone has a neutral formal charge, and is only slig ...

(traces found)

Terpenoid The terpenoids, also known as isoprenoids, are a class of naturally occurring organic compound, organic chemicals derived from the 5-carbon compound isoprene and its derivatives called terpenes, diterpenes, etc. While sometimes used interchangeabl ...

s * Citronellal * Citronellol * Citronellic acid * Isopulegol * (6R)-(E)-2,6-Dimethyl-2-octen-1,8-dioic acid Both 2,4-Dihydroxyacetophenone and 2-Methyl-5,7-dihydroxychromone are phenolic ketones which cause the pH-dependent color changes of the secretion. (6R)-(E)-2,6-Dimethyl-2-octen-1,8-dioic acid is an acyclic monoterpene previously undocumented in insects. However, the chemical is well known to be a urinary

metabolite In biochemistry, a metabolite is an intermediate or end product of metabolism. The term is usually used for small molecules. Metabolites have various functions, including fuel, structure, signaling, stimulatory and inhibitory effects on enzymes, c ...

in mammals, with overproduction resulting in toxic

acidosis Acidosis is a biological process producing hydrogen ions and increasing their concentration in blood or body fluids. pH is the negative log of hydrogen ion concentration and so it is decreased by a process of acidosis. Acidemia The term ac ...

in various species.

Gallery

References

External links

* Photos of the ant. {{Taxonbar, from=Q1940969 saundersi Hymenoptera of Asia Endemic fauna of Borneo Insects of Brunei Insects of Malaysia Exploding animals Insects described in 1889 Taxa named by Carlo Emery