Zophobas atratus

Zophobas atratus
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Coleoptera
Family:	Tenebrionidae
Genus:	Zophobas
Species:	Z. atratus
Binomial name
	Zophobas atratus; (Fabricius, 1775)
Synonyms
	Tenebrio atratus Fabricius, 1775; Helops morio Fabricius, 1777; Tenebrio elongatus Palisot de Beauvois, 1817; Zophobas rugipes Kirsch, 1866; Zophobas concolor Wollaston, 1870; Zophobas alternans Kraatz, 1880; Zophobas batavorum Marcuzzi, 1959;

Zophobas atratus is a species of darkling beetle, whose larvae are known by the common name superworm, kingworm, barley worm, morio worm or simply Zophobas. Superworms are common in the reptile pet industry as food, along with giant mealworms (Tenebrio molitor larvae treated with juvenile hormone^{[citation needed]}).

The larvae resemble very large mealworms, about 50 to 60 mm (1.7–2.25 in) long when full size, but unlike mealworms, the ends of their bodies are very dark, almost resembling a black color. Once they reach sufficient maturity, the larvae pupate, emerging with a white to light brown colour; eventually darkening to black. The larvae fail to pupate if kept in a high density with many other larvae and plentiful food. Keeping Z. atratus this way is commonly used to hinder pupation. To mature the larvae, they must be isolated for about 7–10 days. They will then, upon maturation, emerge from their pupal stage as darkling beetles.^[6]

Zophobas atratus is generally accepted by captive lizards, turtles, frogs, salamanders, birds, koi and other insectivorous animals. Their nutritional values are similar to those of mealworms, so it is possible that supplementation with calcium is necessary if they are used as a staple food item. In some cases they are preferred over mealworms due to their softer exoskeleton,^[7] making them more digestible to some reptiles. The larvae are odor-free, but the adult beetles possess a pungent chemical defense that may be released when provoked. Zophobas atratus can easily be contained, making them ideal for breeding to feed a collection of captive insectivores. The nutritional profile of the larvae is "46.80% proteins, 43.64% lipids, 8.17% ashes and 1.39% carbohydrates."^[8]

Relationship with humans

As pet feed

As with the popular mealworm, Z. atratus larvae (commonly known as superworms, and under the name Zophobas morio) are widely used in pet care, more specifically as feed.

Superworms are relatively high in protein and fat, which make them attractive pet feed for captive reptiles, amphibians, fish, and birds, and other types of insectivores like ants. Their ability to stay alive without eating for 1–2 weeks makes the keeping process highly feasible for bulk commercial availability around the world. However, pet owners are advised to keep them in warm temperatures as, unlike the mealworm, superworms do not enter the process of hibernation. They are also known to bite and agitate when threatened by handling, although the bite is not very painful.

As waste disposal agents

Larvae of Zophobas atratus, Tenebrio molitor and Tenebrio obscurus all have been found to consume expanded polystyrene foam.^[9] Zophobas atratus breaks down polystyrene through a two-stage process: first by mechanically shredding the plastic into smaller pieces through chewing, which exposes pieces to oxygen atoms, and then by using bacterial gut enzymes to depolymerize the pieces.^[10]^[11] Zophobas atratus larvae fed with a polystyrene diet were more active and managed to gain a slight amount of weight compared to the same type of larvae on a starvation diet.^[12]^[13]

Distribution

This beetle occurs naturally in tropical regions of Central and South America,^[14] but has spread across the world for use as food for reptiles and other insectivorous pets.^{[citation needed]}

Taxonomy

The name Zophobas morio is still very widely in use in the scientific literature, although it has been synonymised with Z. atratus.^[1] Since Z. morio was published later (in the year 1777) than Z. atratus (published in 1775), the former name is a junior subjective synonym of the latter, and Z. atratus is the valid name of this species.