''Spinochordodes tellinii'' is a parasitic nematomorph hairworm whose

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

e develop in

grasshoppers Grasshoppers are a group of insects belonging to the suborder Caelifera. They are among what is possibly the most ancient living group of chewing herbivorous insects, dating back to the early Triassic around 250 million years ago. Grasshop ...

and

crickets Crickets are orthopteran insects which are related to bush crickets, and, more distantly, to grasshoppers. In older literature, such as Imms,Imms AD, rev. Richards OW & Davies RG (1970) ''A General Textbook of Entomology'' 9th Ed. Methuen 8 ...

. This

parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

is able to influence its host's behavior: once the parasite is grown, it causes its grasshopper host to jump into water, where the grasshopper will likely drown. The parasite then leaves its host; the adult worm lives and reproduces in water. ''S. tellinii'' does not influence its host to actively seek water over large distances, but only when it is already close to water. The microscopic larvae are ingested by their insect hosts and develop inside them into worms that can be three to four times longer than the host. The precise molecular mechanism underlying the modification of the host's behaviour is not yet known. A study in 2005 indicated that grasshoppers which contain the parasite express, or create, different

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

s in their brains compared to uninfected grasshoppers. Some of these proteins have been linked to neurotransmitter activity, others to geotactic activity, or the body's response to changes in gravity. Furthermore, it appears that the parasite produces proteins from the Wnt family that act directly on the development of the central nervous system and are similar to proteins known from other insects, suggesting an instance of

molecular mimicry Molecular mimicry is defined as the theoretical possibility that sequence similarities between foreign and self-peptides are sufficient to result in the cross-activation of autoreactive T or B cells by pathogen-derived peptides. Despite the preva ...

. A similar parasitic worm is ''

Paragordius tricuspidatus ''Paragordius tricuspidatus'' belongs to the phylum Nematomorpha, and is known for manipulating the behavior of its host, the cricket ''Nemobius sylvestris''. In its larval stage, the worm is microscopic, but grows into a large worm () inside i ...

''.

References

External links

*
Video of ''Spinochordodes tellinii''
in which it causes a cricket to drown and then emerges from it. {{Taxonbar, from=Q1078014 Nematomorpha Parasitic protostomes Parasites of insects Suicide-inducing parasitism Animals described in 1888 Taxa named by Lorenzo Camerano