Steinernema Australe
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Steinernema is a genus of
nematode The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-Parasitism, parasitic nematodes also known as eelworms. They are a diverse animal phylum inhab ...
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, dig ...
. 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.


Life cycle

Species form
symbiotic relationships Symbiosis (from Ancient Greek, Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different Organism, biological organisms, be it Mutualism (biolog ...
with ''
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 no ...
'' 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. 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 to infect agricultural pests. They can be used against a wide variety of species, including
weevils Weevils are beetles belonging to the superfamily Curculionoidea, known for their elongated snouts. They are usually small, less than in length, and herbivorous. Approximately 97,000 species of weevils are known. They belong to several families, ...
,
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 A gnat () is any of many species of tiny flying insects in the dipterid suborder Nematocera, especially those in the families Mycetophilidae, Anisopodidae and Sciaridae. They can be both biting and non-biting. Most often they fly in large num ...
and mole crickets.


References


Further reading

* * * {{Taxonbar, from=Q5304420 Rhabditida Rhabditida genera