Hexamermis, parasitic worm Minimize

May 2004. A large worm (approx. 20 cm) emerged from the abdomen of the grasshopper in the picture. The grasshopper was collected during a pest survey in Solomon Islands. A few days later, a similar worm emerged from another species of grasshopper. Can anyone give an information on this type of worms, in particularly their biology, ecology, host specificity, and if they provide some contribution to controlling grasshoppers? Needless to say, the grasshopper did not survive the exit of the worm: it died a short time later.

This appears to be a gordian or horsehair worm (also said to be a mermithid worm), of which there are about 300 species belonging to the class Nematomorpha, phylum Aschelminthes. It was almost certain to be of the genus Hexamermis. A better picture of the tail or a specimen of the nematode would confirm its identity.

The juveniles are parasitic in arthropods and the adults are free-living in fresh and salt water. In Papua New Guinea, they are not infrequently found emerging from grasshoppers in small puddles or ground water after rain. It seemed as if infested hosts were drawn to water to enable the mature worms to emerge and commence their free living phase. They did not appear to be common enough to exercise any significant biological control over their hosts. See:

www.qmuseum.qld.gov.au/inquiry/oddspot/gordianworms.asp
bsweb.unl.edu/emb/janovy/ben/info.html
www.ag.ndsu.nodak.edu/aginfo/entomology/entupdates/Indoor_pest/horsehair_worm.htm
www.uky.edu/Agriculture/Entomology/entfacts/struct/ef613.htm
 
Original:
tech.groups.yahoo.com/group/pestnet/message/2327

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