Entomopathogenic nematodes (EPN) are a group of nematodes (thread worms), that cause death to insects. The term entomopathogenic has a Greek origin, with entomon, meaning insect, and pathogenic, which means causing disease. They are animals that occupy a bio control middle ground between microbial pathogens and predator/parasitoids. Although many other parasitic thread worms cause diseases in living organisms (sterilizing or otherwise debilitating their host), entomopathogenic nematodes are specific in only infecting insects. Entomopathogenic nematodes (EPNs) live parasitically inside the infected insect host, and so they are termed as endoparasitic. They infect many different types of insects living in the soil like the larval forms of moths, butterflies, flies and beetles as well as adult forms of beetles, grasshoppers and crickets. EPNs have been found all over the world in a range of ecologically diverse habitats. They are highly diverse, complex and specialized. The most commonly studied entomopathogenic nematodes are those that can be used in the biological control of harmful insects, the members of Steinernematidae and Heterorhabditidae. They are the only insect-parasitic nematodes possessing an optimal balance of biological control attributes.
The nematodes or roundworms constitute the phylum Nematoda, with plant-parasitic nematodes also known as eelworms. They are a diverse animal phylum inhabiting a broad range of environments. Less formally, they are categorized as helminths, but are taxonomically classified along with arthropods, tardigrades and other moulting animals in the clade Ecdysozoa. Unlike the vaguely similar flatworms, nematodes have a tubular digestive system, with openings at both ends. Like tardigrades, they have a reduced number of Hox genes, but their sister phylum Nematomorpha has kept the ancestral protostome Hox genotype, which shows that the reduction has occurred within the nematode phylum.
Tipula paludosa is a species of true craneflies, family Tipulidae. It is also known as the European crane fly or the marsh crane fly. It is a pest in grasslands of Northwest Europe and has been accidentally introduced to North America.
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.
Steinernema scapterisci, the mole cricket nematode, is a species of nematode in the order Rhabditida. It is a parasite of insects in the order Orthoptera, the grasshoppers, crickets and their allies. Native to southern South America, it was introduced into Florida in the United States in an effort to provide a biological control of pest (Neoscapteriscus) mole crickets.
The xenortides (A-D) are a class of linear peptides isolated from the bacterium Xenorhabdus nematophila, a symbiont of the entomopathogenic nematode Steinernema carpocapsae. This class of compounds is known for their insect virulence and cytotoxic biological activities. The tryptamide containing compounds show higher biological activity than the phenylethylamides. The most biologically active compound was found to be xenortide B with a potency of less than 1.6 μM activity against Trypanosoma brucei rhodesiense and Plasmodium falciparum (malaria), however it is also the most toxic to mammalian cells which limits its viability as a treatment.
Xenorhabdus bovienii is a bacterium from the genus of Xenorhabdus which has been isolated from the nematodes Steinernema bibionis, Steinernema krsussei, Steinernema affine, Steinernema carpocapsae, Steinernema feltiae, Steinernema intermedium, Steinernema jollieti and Steinernema weiseri. Xenorhabdus bovienii produces N-Butanoylpyrrothine, N-(3-Methylbutanoyl)pyrrothine and Xenocyloins.
Xenorhabdus griffiniae is a bacterium from the genus of Xenorhabdus which has been isolated from the nematode Steinernema hermaphroditum in Indonesia.
Xenorhabdus hominickii is a bacterium from the genus of Xenorhabdus which has been isolated from the nematodes Steinernema karii in Kenya and Steinernema monticolum from Korea.
Xenorhabdus indica is a bacterium from the genus of Xenorhabdus which has been isolated from the nematodes Steinernema thermophilum and Steinernema yirgalemense. Xenorhabdus indica produces the Taxlllaids A–G.
Xenorhabdus khoisanae is a bacterium from the genus Xenorhabdus which has been isolated from the nematode Steinernema khoisanae in the Western Cape Province in South Africa.
Xenorhabdus kozodoii is a bacterium from the genus Xenorhabdus which has been isolated from the nematode Steinernema arenarium in Voronez in Russia and from the nematode Steinernema apuliae in Italy.
Xenorhabdus poinarii is a bacterium from the genus Xenorhabdus which has been isolated from the nematodes Steinernema glaseri and Steinernema cubanum.
Steinernema carpocapsae is an entomopathogenic nematode and a member of the family Steinernematidae. It is a parasitic roundworm that has evolved an insect-killing symbiosis with bacteria, and kills its hosts within a few days of infection. This parasite releases its bacterial symbiont along with a variety of proteins into the host after infection, and together the bacteria and nematode overcome host immunity and kill the host quickly. As a consequence, S. carpocapsae has been widely adapted for use as a biological control agent in agriculture and pest control. S. carpocapsae is considered a generalist parasite and has been effectively used to control a variety of insects including: Webworms, cutworms, armyworms, girdlers, some weevils, and wood-borers. This species is an example of an "ambush" forager, standing on its tail in an upright position near the soil surface and attaching to passing hosts, even capable of jumping. As an ambush forager, S. carpocapsae is thought to be especially effective when applied against highly mobile surface-adapted insects. S. carpocapsae can sense carbon dioxide production, making the spiracles a key portal of entry into its insect hosts. It is most effective at temperatures ranging from 22–28 °C (72–82 °F).
The Steinernematidae are a family of nematodes in the order Rhabditida.
Gnathamitermes perplexus, the long-jawed desert termites or tube-building termites, is a species of termite in the family Termitidae. It is found in Central America and North America. The species creates tunnels, with both colony founders and workers transporting sand to excavate tunnels using their mandibles. The species is particularly susceptible to infectious nematodes such as Steinernema riobrave.
Steinernema is a genus of nematodes in the family of Steinernematidae. The genus Steinernema is named after the nematologist Gotthold Steiner.
Steinernema xueshanense is a nematode species from the genus of Steinernema. Steinernema xueshanense is named after the Xue Shan mountains.
Steinernema riobrave is a species of nematodes belonging to the family Steinernematidae.
Necromeny is a symbiotic relationship where an animal infects a host and waits inside its body until its death, at which point it develops and completes its life-cycle on the cadaver, feeding on the decaying matter and the subsequent bacterial growth. As the necromenic animal benefits from the relationship while the host is unharmed, it is an example of commensalism.
