Presenting an exceptional biological diversity and an extraordinary ecological one, the coleopterans constitute the most extensive order of all the animal world. They are an Order that belongs to the Class Insecta or Class of insects and they are invertebrate animals that are really fascinating.
Through this article that we present to you from Green Ecologist we explain everything about the magnificent world of Coleoptera: what are they, characteristics, types and examples. If these little living beings arouse your curiosity, we encourage you to continue reading this beetle guide.
What are Coleoptera
The Beetles (word that originates from the Greek koleos, which means "box or case", and from the Greek pteron, which means "wing") or also called beetles, form an order of holometabolic insects known as Coleoptera. Taxonomically speaking, they form more than 40% of the diversity described for Hexapoda worldwide, they are known between 360,000 and 400,000 species currently described. In this way, it includes a quarter of all the species described so far and, in addition to being the zoological group with the largest number of species in the entire biosphere, it is the most diverse animal order of the planet.
Beetles are a monophyletic group, with the oldest coleopteroid fossil dating to the Lower Permian (270 million years ago). However, the first true Coleoptera appeared in the Upper Permian stage (about 250 million years ago) and in the Upper Triassic (240-220 million years) where up to twenty families are recognized.
We invite you to learn more about the Classification of insects with this other post from Green Ecologist.
Beetle characteristics
Coleoptera are characterized by presenting great morphological variability, a characteristic that has allowed them to colonize all types of environments and habitats, from freshwater to marine environments. This has made them the group of animals with the greatest evolutionary success. But, how are beetles? These are the main Coleoptera characteristics:
- Like insects, the body of beetles has three characteristic tagmas: the head, the thorax and the abdomen. However, the existence of a pterothorax covered by the elytra (totally hardened modified wings with a protective function to the second pair of wings, the posterior part of the thorax and the abdomen), gives the sensation that the body is divided into an anterior part, formed by the head and the prothorax, and a posterior one under the elytra.
- Commonly, the head is porgnata, that is, the longitudinal axis of the rest of the body coincides with that of the head (Angle of 180or). It is endowed with a cephalic capsule, where the following regions are distinguished: the forehead, the vertex between the forehead and the occiput and some lateral areas known as genas, where the compound eyes are located. In this capsule, a pair of antennas and the mouthparts are connected, the latter endowed with an orthopterid structure that facilitates chewing.
- The thorax is characterized by a sharp division into the prothorax and pterothorax. The first section is free while the second forms a functional unit. The metathoracic wings are membranous and fold transversely below the elytra, being normally longer than the elytra.
- The abdomen is divided into ten or eleven segments, of which there are 5 or 6 visible sternites (corresponding to segments III to VII or VIII).
- Regarding the size of the individuals, this usually oscillates between the 0.3 mm of some Ptiliidae and the 200 mm of the females of Titanus giganteus Y Xixuthrus heros (Cerambycidae).
Coleoptera feeding
Regarding the diet of these organisms, there is a very diverse range of food sources, as varied as their ways of life. Coleoptera can feed on flowers, fruits, manure, other animals, seeds, leaves, pollen, roots, among many other options. In fact, the typology of their diet allows them to be classified into three suborders of coleopterans according to their diet:
- Suborder Adephaga, or carnivorous beetles.
- Suborder Myxophaga, or Herbivorous Coleoptera.
- Suborder Polyphaga, or Omnivorous Coleoptera.
Coleoptera life cycle
Commonly, coleopterans reproduce sexually, while parthenogenesis occurs exceptionally.
It all starts when males attract females through aggregation hormones while females attract males through pheromones. or, also, emitting sounds. They court and then reproduce. Hence, a very variable size and number of eggsfrom a large one to several hundred or thousands of small eggs. Their life cycles are usually univoltinous; however, in warm areas and with enough food, two or more generations can occur per year.
Types and examples of coleopterans
4 suborders are considered: Archostemata, Myxophaga, Adephaga and Polyphaga. The suborders that contain coleopteran species of agricultural interest are Adephaga and Polyphaga and, therefore, we focus on these.
- Adephaga: Developed coxas that divide the first abdominal segment. Notopleural suture present. Tarsal formula 5.5.5.
- Polyphaga: Developed coxas do not divide the first abdominal segment. Notopleural suture absent.
Some examples of coleopterans more curious are the titan beetle (Titanus giganteus), which can reach a size of 17 centimeters, the eastern firefly (Photinus pyralis), characterized by emitting bioluminescence, and the cantárida (Lytta vesicatoria), one of the species of beetle poisonous to humans. And there is still an immensely curious and peculiar variety of coleopteran species.
Coleoptera pests
There are several species of coleopterans that can cause damage to horticultural crops or garden plants, which makes them potentially pest-causing animals.
A common example is coleopteran pests in rapeseed. Normally, this event becomes evident when the larvae have exited the rapeseed pods through openings. Previously, inside the pod, these larvae have eaten the grains of the pods. Consequently to the perforations that they create in the pods, the water penetrates inside them causing outgrowths.
If you want to read more articles similar to Coleoptera: what are they, characteristics, types and examples, we recommend that you enter our Biodiversity category.
Bibliography- Valencian generalitat. (2022). Penyal d'Ifac Natural Park: Coleoptera Order. Retrieved from: http://www.parquesnaturales.gva.es/es/web/insectarium-virtual-del-parc-natural-del-penyal-d-ifac/orden-coleoptera
- Jerez, V., & Moroni, J. (2006). Diversity of aquatic beetles in Chile. Gayana (Concepcion), 70(1), 72-81.
- BASF. (2022). Coleoptera. Retrieved from: https://www.agro.basf.es/es/Servicios/Gu%C3%ADa-de-plagas/Cole%C3%B3pteros.html
- Magazine IDE @ - SEA, nº 55 (06-30-2015): 1-18. Class: Insecta Order COLEOPTERA. Recovered from: http://sea-entomologia.org/IDE@/revista_55.pdf
