''Howardula aoronymphium'' is a species 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 ...

that infects specialist mushroom-feeding fruit flies such as ''

Drosophila falleni . ''Drosophila falleni'' is a species of fly found in northeastern North America. A mycophagous insect, it is known to feed on the fruit bodies (mushrooms) of several genera of fungi, including ''Agaricus'', ''Amanita'', '' Agrocybe'', ''Boletus ...

'' and ''

Drosophila neotestacea ''Drosophila neotestacea'' is a member of the ''testacea'' species group of ''Drosophila''. Testacea species are specialist fruit flies that breed on the fruiting bodies of mushrooms. These flies will choose to breed on psychoactive mushrooms s ...

''. Mated female nematodes pierce the fly larva cuticle and take up residence in the

hemolymph Hemolymph, or haemolymph, is a fluid, analogous to the blood in vertebrates, that circulates in the interior of the arthropod (invertebrate) body, remaining in direct contact with the animal's tissues. It is composed of a fluid plasma in which ...

(insect blood) where they mature alongside the fly. When the adult fly ecloses, the nematode motherworm has reached full size and sheds juvenile nematodes into the hemolymph which are eventually excreted by either the fly anus or

ovipositor The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typical ...

. '' Howardula'' nematodes can severely impact fly egg development, as infection can effectively sterilize some species. ''Howardula aoronymphium'' are attracted to mushroom sites by cuing in on specific odourants that are common in rotting mushrooms. However the odourants that attract ''H. aoronymphium'' to mushrooms are different from the odours that attract its fly host '' D. falleni''. Yet when ''D. falleni'' are infected by ''H. aoronymphium'', their olfactory preferences differ. Infected flies become more averse to acetate-containing compounds such as

ethyl acetate Ethyl acetate ( systematically ethyl ethanoate, commonly abbreviated EtOAc, ETAC or EA) is the organic compound with the formula , simplified to . This colorless liquid has a characteristic sweet smell (similar to pear drops) and is used in glues ...

propyl acetate Propyl acetate, also known as propyl ethanoate, is an organic compound. Nearly 20,000 tons are produced annually for use as a solvent. This colorless liquid is known by its characteristic odor of pears. Due to this fact, it is commonly used in ...

. Conversely, infected flies become more attracted to 1-nonanol. ''Howardula aoronymphium'' can be compared to other insect-infecting nematodes such as ''

Steinernema Steinernema is a genus of nematodes in the family of Steinernematidae. The genus ''Steinernema'' is named after the nematologist Gotthold Steiner. Life cycle Species form symbiotic relationships with ''Xenorhabdus'' and '' Photorhabdus'' ba ...

'' and '' Heterorhabiditis''. These nematodes are used as biological control agents, as they efficiently kill their insect prey within days after infection. However unlike these nematodes, ''Howardula aoronymphium'' requires its host fly to survive into adulthood, and does not increase larval mortality. Moreover ''Howardula aoronymphium'' is quite specific to mushroom-feeding flies, while other insect-infecting nematodes can be more generalist worms capable of infecting a wide variety of insects. The inherited bacterial symbiont ''

Spiroplasma poulsonii ''Spiroplasma poulsonii'' are bacteria of the genus ''Spiroplasma'' that are commonly endosymbionts of flies. These bacteria live in the hemolymph (insect blood) of the flies, where they can act as reproductive manipulators or defensive symbionts ...

'' can defend flies against ''Howardula'' infection by attacking the nematodes using toxins analogous to sarcin or

ricin Ricin ( ) is a lectin (a carbohydrate-binding protein) and a highly potent toxin produced in the seeds of the castor oil plant, ''Ricinus communis''. The median lethal dose (LD50) of ricin for mice is around 22 micrograms per kilogram of body ...

References

Parasitic nematodes of animals Nematodes described in 1959 {{Nematode-stub

See also

References