#mermithidae

[reanimateobjects]

[drhoz]

We found this worm in the garden on 2012-05-21. It seems to be a nematode from the family mermithidae but we're not sure. The metal fencing material it is climbing on is made from wire a bit more than 1 mm in diameter. That makes the worm about 0.1 mm in diameter. It was more than 10 cm long making its length to width ratio about 1000:1. My length to width ratio is about 4.5:1.

[oaresearchpaper]

The pest Spodoptera frugiperda, when it invades Africa, is associated with a parasitic fauna, justifying the need to characterize the genetic diversity of its natural enemies in Senegal. Thus the rDNA of the large subunit, 28S was amplified. The study revealed the existence of 12 species of parasitoids obtained and 3 species of entomopathogenic nematodes. Parasitoids are divided into two orders (Hymenoptera and Diptera) and five families (Ichneumonidae, Braconidae, Eulophidae, Encyrtidae and Tachinidae). These parasitoids are Sinophorus exartemae, Chelonus sp., Parapanteles sp., Dolichogenidea sp. 1, Dolichogenidea sp. 2, Meteorus sp., Meteorus orocrambivorus, Euplectrus phthorimaeae, Prochiloneurus testaceus, Ooencyrtus masii, Drino sp. and Senometopia cariniforceps. Nematodes are members of the family Mermithidae and correspond to Hexamermis sp., Mermithidae sp. 1 and Mermithidae sp. 2. All these species attack the larval stage except O. masii which is oophagous. This study also reports new associations between S. frugiperda and the parasitoids S. exartemae, M. orocrambivorus, E. phthorimaeae, P. testaceus, O. masii and S. cariniforceps. To our knowledge, these six species, in addition to Drino sp., have just been known in the entomological fauna of Senegal. Therefore, it is urgent to protect these auxiliaries from the abusive and inappropriate use of chemical insecticides for sustainable management.

[drhoz]

We found these in our garden during a rainy morning in late spring. They were scattered under a plum tree but we collected them into a pile to get photos and video. Not sure what species these are but they most resemble nematodes in the Mermithidae family. They resemble horsehair worms (Nematomorpha) but there are no bodies of water nearby. They may be a species in the Mermis genus and like horsehair worm, they are parasites of insects. Their behavior resembles Mermis nigrescens but there are few grasshoppers (their common hosts) but we do have a lot of tree crickets in our garden. They probably had come to the soil surface to mate. Their scanning behavior is likely them sensing light to determine their direction. By noon , these worms had disappeared from the surface.

[drhoz]

[drhoz]

#1900 - Mermithid Nematode

Photo by Marty Moore, in Ashford, New South Wales, who found this unfortunate Huntsman Spider in his dog’s water bowl, and the chest-bursting nematode that was probably hoping the spider had flung itself into a creek. 

Like the better known Gordion or Horsehair Worms of the Order Nematomorpha, Mermithids are parasites, mainly of arthropods. Most species are known from insects, including at least 25 that are known from mosquito larvae, but some are recorded from spiders (as here), scorpions, and crustaceans. A few are known from segmented worms (earthworms and leeches) and molluscs. Taxonomically they’re not well understood, being almost entirely lacking in anatomical features, and they’re usually collected by entomologists rather than nematode specialists. 

As with the Horsehair Worms, some Mermithids can alter the host behaviour when they’re ready to emerge and lay their eggs, making the animal desperately thirsty by altering the osmolytic balance. The newly hatched larva are free-living, and immediately seek out a suitable host. If the host is an aquatic insect with a flying adult, they can then jump hosts as their initial host is eaten by a predator like the spider here. 

Others live on land, emerging with rain to climb vegetation and lay their eggs where they may get eaten - the eggs possess long branching filaments to help them stick. 

[astronomy-to-zoology]

Mermis nigrescens

...is a large species of parasitic mermithid nematode that is native to the nearctic and palearctic ecozones. M.nigrescens usually parasitize grasshoppers and are ingested as eggs. Once an egg enters a grasshopper the outer layers of the egg will rub off and the larvae will move out. Once hatched the larvae will pierce the gut wall and enter the body cavity where they will feed on body fluids. in 3-6 weeks the will emerge from the hosts, crawl into the soil, molt, and mate. Females will spend their winter in the soil and will emerge on rainy or dewy morning in spring/summer to climb up on plants and lay their eggs. 

Phylogeny

Animalia-Nematoda-Adenophorea-Mermithida-Mermithidae-Mermis-M.nigrescens

Image(s): Beentree

[mindmonsters88-blog]

Mermithidae crawling out of a dead spider.