''Steinernema'' is a genus of

nematode The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (h ...

s in the family of

Steinernematidae The Steinernematidae are a family of nematodes in the order Rhabditida. Nematodes of the genus ''Steinernema'' are obligate insect parasites that inhabit soil. ''Xenorhabdus'' bacteria occupy nematode insecticide and synergistically kill, dige ...

. The genus ''Steinernema'' is named after the

nematologist Nematology is the scientific discipline concerned with the study of nematodes, or roundworms. Although nematological investigation dates back to the days of Aristotle or even earlier, nematology as an independent discipline has its recognizable ...

Gotthold Steiner Gotthold is a name of German origin. People with the name include: People with the given name *Gotthold Eisenstein (1823–1852), German mathematician * Gotthold Gloger (1924–2001), German writer and painter * Samuel Gotthold Lange (1711-1781), ...

. Nematodes of this genus have been shown to be effective as a biological control for agricultural pests of the Scarabaeidae family, such as ''

Maladera formosae ''Maladera formosae'', commonly known as the Asiatic garden beetle and formerly known as ''Maladera castanea'', is a species of beetle in the family Scarabaeidae. It is native to Japan, China, South Korea, North Korea, and Russia but was introduc ...

''.

Life cycle

Species form

symbiotic relationships Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term

Xenorhabdus ''Xenorhabdus'' is a genus of motile, gram-negative bacteria from the family of the Morganellaceae. All the species of the genus are only known to live in symbiosis with soil entomopathogenic nematodes from the genus '' Steinernema''. Although n ...

'' and ''

Photorhabdus ''Photorhabdus'' is a genus of bioluminescent, gram-negative bacilli which lives symbiotically within entomopathogenic nematodes, hence the name ''photo'' (which means light producing) and ''rhabdus'' (rod shape). ''Photorhabdus'' is known to be ...

'' bacteria. The free-living third stage juvenile, termed a dauer juvenile, enters its insect hosts through natural openings, such as the mouth, anus, and spiracles. Steinernema scapterisci at Scapteriscus vicinus

Steinernema scapterisci at Scapteriscus vicinus

Bacterial cells from the intestines are regurgitated into the insect. The insect hemolymph provides a rich medium for the bacterial cells which grow, releasing toxins and exoenzymes, causing the insect host to die from septicemia. The bacteria also produce other compounds to protect the insect from other microbes in the soil. The nematode moves out of its developmentally arrested third, nonfeeding stage, triggered by either bacterial or insect food signals. The nematodes feed on the bacteria and moult to the fourth stage, reaching adulthood within a few days. with separate male and female individuals. Nematode development continues for two to three generations. When insufficient nutrient remain adult development is suppressed. Developmentally arrested third stage juveniles accumulate and emerge into the soil, where they may survive for months until a new suitable host is found.

Species

The following species have been described:

Use in agriculture

Species of this genus can infect insects and are used as a

biopesticide A biopesticide is a biological substance or organism that damages, kills, or repels organisms seens as pests. Biological pest management intervention involves predatory, parasitic, or chemical relationships. They are obtained from organisms incl ...

to infect agricultural pests. They can be used against a wide variety of species, including

weevils Weevils are beetles belonging to the Taxonomic rank, superfamily Curculionoidea, known for their elongated snouts. They are usually small – less than in length – and Herbivore, herbivorous. Approximately 97,000 species of weevils are known. ...

cutworms Cutworms are moth larvae that hide under litter or soil during the day, coming out in the dark to feed on plants. A larva typically attacks the first part of the plant it encounters, namely the stem, often of a seedling, and consequently cuts it ...

gnats GNAT is a free-software compiler for the Ada programming language which forms part of the GNU Compiler Collection (GCC). It supports all versions of the language, i.e. Ada 2012, Ada 2005, Ada 95 and Ada 83. Originally its n ...

and mole crickets.

Life cycle

Species

Use in agriculture

References

Further reading