The Hercules beetle (''Dynastes hercules'') is a species of

rhinoceros beetle Dynastinae or rhinoceros beetles are a subfamily of the scarab beetle family (Scarabaeidae). Other common names – some for particular groups of rhinoceros beetles – include Hercules beetles, unicorn beetles or horn beetles. Over 1 ...

native to the

rainforests Rainforests are characterized by a closed and continuous tree canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforest can be classified as tropical rainforest or temperate rainforest ...

Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...

, and the

Lesser Antilles The Lesser Antilles ( es, link=no, Antillas Menores; french: link=no, Petites Antilles; pap, Antias Menor; nl, Kleine Antillen) are a group of islands in the Caribbean Sea. Most of them are part of a long, partially volcanic island arc bet ...

. It is the longest extant species of beetle in the world, and is also one of the largest flying insects in the world.

Etymology

''Dynastes hercules'' is known for its tremendous strength and is named after

Hercules Hercules (, ) is the Roman equivalent of the Greek divine hero Heracles, son of Jupiter and the mortal Alcmena. In classical mythology, Hercules is famous for his strength and for his numerous far-ranging adventures. The Romans adapted the ...

, a hero of

classical mythology Classical mythology, Greco-Roman mythology, or Greek and Roman mythology is both the body of and the study of myths from the ancient Greeks and ancient Romans as they are used or transformed by cultural reception. Along with philosophy and poli ...

who is famed for his great strength.

Taxonomy

''D. hercules'' has a complex taxonomic history and has been known by several synonyms. It is in the subfamily

Dynastinae Dynastinae or rhinoceros beetles are a subfamily of the scarab beetle family (Scarabaeidae). Other common names – some for particular groups of rhinoceros beetles – include Hercules beetles, unicorn beetles or horn beetles. Over 1 ...

(rhinoceros beetles) in the larger family

Scarabaeidae The family Scarabaeidae, as currently defined, consists of over 30,000 species of beetles worldwide; they are often called scarabs or scarab beetles. The classification of this family has undergone significant change in recent years. Several sub ...

(commonly known as scarab beetles). Not counting subspecies of ''D. hercules'', seven other species are recognized in the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

Description

Adult body sizes (not including the thoracic horn) vary between in length and in width. Male Hercules beetles may reach up to in length (including the horn), making them the longest species of beetle in the world, if jaws and/or horns are included in the measurement. The size of the horn is naturally variable, more so than any variation of the size of legs, wings, or overall body size in the species. This variability results from developmental mechanisms that coincide with genetic predisposition in relation to nutrition, stress, exposure to parasites, and/or physiological conditions. ''Dynastes hercules'' is highly

sexually dimorphic Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

, with only males exhibiting the characteristic horns (one on the head, and a much larger one on the prothorax). The body of males is black with the exception 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 ...

, which can have shades of olive-green. They have a black suture with sparsely distributed black spots elsewhere on the elytra. They have a slightly iridescent coloration to their elytra, which varies in color between specimens and may be affected by the humidity of the local environment in which they develop.. At low humidity the elytra are olive-green or yellow in color, but darken to black at higher humidity due to its hygrochromic properties. Females of ''D. hercules'' have punctured elytra which are usually entirely black, but sometimes have the last quarter of the elytra colored in the same way as the males. File:Dynastes hercules (female).jpg, Female File:Dynastes hercules hercules01.JPG, Male File:" Hercules beetle illustration from The Naturalist's Miscellany (1789-1813) by George Shaw (1751-1813). ".jpg, Hercules beetle illustration from ''The Naturalist's Miscellany'' (1789–1813) by George Shaw (1751–1813).

Distribution and habitat

Populations of ''D. hercules'' may be found from southern Mexico to Bolivia in mountainous and lowland rain forests. Known populations include the Lesser Antilles, Trinidad and Tobago, Brazil, Ecuador, Colombia, and Peru. Chromosomal analysis has shown that the genus ''Dynastes'' in fact originated from South America.

Life cycle

Not much is known about the life cycle in the wild, but much evidence has been gained through observations of captive-bred populations. The mating season for adults typically occurs during the

rainy season The rainy season is the time of year when most of a region's average annual rainfall occurs. Rainy Season may also refer to: * ''Rainy Season'' (short story), a 1989 short horror story by Stephen King * "Rainy Season", a 2018 song by Monni * '' ...

(July to December). Females have an average gestation period of 30 days from copulation to egg-laying, and may lay up to 100 eggs on the ground or on dead wood. The eggs have an incubation period of approximately 27.7 days before they hatch. Once hatched, the larval stage of the Hercules beetle may last up to two years in duration, where it will go through 3 metamorphosis stages, also known as

instars An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or ass ...

. The larvae have a yellow body with a black head. The larvae can grow up to in length and weigh more than 100 grams. In laboratory conditions at 25 ± 1° C, the first instar stage lasts an average of 50 days, the second stage an average of 56 days, and the third an average of 450 days. After the third instar stage, the

pupal A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their ...

stage lasts about 32 days, where it will transition into an adult. Adult beetles can live for three to six months in captivity.

Diet and behavior

Diet

The larvae of the Hercules beetle are saproxylophagous, meaning that they feed on rotting wood; they reside in same during their two-year developmental stage. The adult Hercules beetle feeds on fresh and rotting fruit, along with tree sap. Adults carve bark through the use of its synchronous mandibles to easily access the sap of trees. When these mandibles are closed, a narrow opening is formed which can act like a straw to allow consumption of tree sap. They have been observed feeding on peaches, pears, apples, grapes, bananas, and mangoes in captivity.Krell, F., Krell, V. Longevity of the Western Hercules beetle, ''D. grantii'' Horn (Coleoptera: Scarabaeidae: Dynastinae). ''The Coleopterists Bulletin'', vol. 69, 2015, 1p.

Behavior

Within their native rain forest habitats, the adult beetles, which are nocturnal, forage for fruit at night and hide or burrow within the leaf litter during the day. The adult ''D. hercules'' beetles are capable of creating a 'huffing' sound, generated by stridulating their abdomen against their elytra to serve as a warning to predators. Like most insects, communication within the species is a mix of

chemoreception A chemoreceptor, also known as chemosensor, is a specialized sensory receptor which transduces a chemical substance (endogenous or induced) to generate a biological signal. This signal may be in the form of an action potential, if the chemorecept ...

, sight, and mechanical perception. Experiments on ''D. hercules'' have shown that a male placed in the vicinity of a female will immediately orient towards her and seek her out, suggesting chemical communication through strong sexual pheromones.

Combat behavior between males

It has been observed in wild habitat and in captivity that male ''D. hercules'' will engage in combat to win possession and mating rights to a female. Male Hercules beetles typically use their large horns to settle mating disputes; these fights can cause significant physical damage to the combatants but may also include possible damage to the female in the process. During fights, the males attempt to grab and pin their rival between the cephalic and thoracic horns to lift and throw them. The successful male wins mating rights with the female, though the beetles remain

polygynandrous Polygynandry is a mating system in which both males and females have multiple mating partners during a breeding season. In sexually reproducing diploid animals, different mating strategies are employed by males and females, because the cost of ga ...

Physical strength

Reports suggest the Hercules beetle is able to carry up to 850 times its body mass. Actual measurements on a much smaller (and relatively stronger: see square-cube law) species of rhinoceros beetle shows a carrying capacity only up to 100 times their body mass, at which point they can barely move.

Relationship to humans

''Dynastes hercules'' does not negatively affect human activities, either as an agricultural pest or disease vector. The beetles can be kept as pets. Larvae excrement has been shown to contain β-mannanase, a bacteria synthesized enzyme that

hydrolyzes Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolysi ...

hemicellulose A hemicellulose (also known as polyose) is one of a number of heteropolymers (matrix polysaccharides), such as arabinoxylans, present along with cellulose in almost all terrestrial plant cell walls.Scheller HV, Ulvskov Hemicelluloses.// Annu Rev ...

that can be used in enzyme based cleaning products. β-mannanase has been successfully extracted and cloned from larvae fecal matter, suggesting that production of bio additive cleaning products may be feasible.

Relationship to the environment

''Dynastes hercules'' is a beneficial contributor to the rain forest

ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...

, primarily during their larval stage where they are saproxylophagous. Feeding on rotting wood assists with

biodegradation Biodegradation is the breakdown of organic matter by microorganisms, such as bacteria and fungi. It is generally assumed to be a natural process, which differentiates it from composting. Composting is a human-driven process in which biodegrada ...

and cycling nutrients in the environment.

References

External links

Family Scarabaeidae - ''Dynastes hercules''
{{Taxonbar, from=Q503799 Dynastinae Beetles described in 1758 Insects of Guadeloupe Beetles of South America Beetles of Central America Taxa named by Carl Linnaeus