Heleidomermis magnapapula

Heleidomermis magnapapula	Contents	Rev 10/23/2024
	Classification	Hosts
	Morphology and Anatomy	Life Cycle
Return to Heleidomermis Menu	Economic Importance	Damage
	Distribution	Management
Return to Mermithidae Menu	Feeding	References
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Classification:

Enoplea

Dorylaimia
Mermithida

Mermithina: Mermithoidea; Mermithidae; Heleidomermis magnapapula Poinar & Mullens, 1987.

A species of parasites of larvae of biting midges larvae in aquatic environments; potentially important in biological control of the host.

Morphology and Anatomy:

Size and shape of the amphidial pouches and spicules and form of the cephalic papillae separate H. magnapupula from previously described species

Small to medium length with a smooth cuticle
Hhead rounded with two anterior lateral and four submedial head papillae
Mouth shifted ventrally, opening near the tips of the lateral head papillae
Circle of six neck papillae arranged in dorsal, ventral, lateral ventral and lateral dorsal positions.
Position of the amphids variable; amphidial openings circular and shifted slightly dorsal; amphidial pouch spherical to slightly ellipticalal.
Nerve endings running from the hypodermis through the cuticle common over the body of both sexes.

Female:

Amphidelphic
Vulva opening circular; vulva flap absent;
Vagina nearly circular; vagina canal straight, terminating at junction of opposing branches of the uteri.
On some females, a pair of small papillae occurred on the ventral or lateral portions of the tail.

Male:

Spicules short, paired, separate, distal tips rounded, proximal portion bent anteriorly;
Tail long; genital papillae arranged on the ventral, lateral and dorsal (near the tail tip) surfaces;
Pharyngeal tube continues almost to the cloaca in the male.

Infective Juvenile:

The infective stage is short and broad, with a thin stylet, a pair of penetration glands,
The stichosomehas eight stichocytes, a small reduced intestine and a genital anlage.
A faint anal opening is present.

Ref: Poinar and Mullens, 1987

Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:

Distribution:

Described from the type host, Culicoides sonorensis (Diptera : Ceratopogonidae) from a dairy wastewater pond in Mira Loma, Riverside Co, California, USA.

A parasite of the blood-sucking midge, Culicoides sonorensis. Endoparasitic in midge larvae . Known host range include C. variipennis but somewhat complicated in that C. variipennis is likely a species complex. In fact, the species sonorensis was fromerly considered a subspecies of variipennis (Brad Mullens, pers. comm.).

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Biology and Ecology:

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Life Cycle:

In Heleidomermis magnapapula parasitizes larvae of the blood-sucking midge, Culicoides sonorensis. The midge is a vector of the bluetongue wirus, an important disease of ruminant animals.

In contrast to the mosquito-infecting mermithids, H. magnapapula the final molt occurs within the host body and the nematode emerges from the insect midge as an adult. After adult mating, the eggs mature and hatch within the female (ovoviparity) and the adult female nematode disperses the mobile second-stage juveniles (J2) into the environment (Mullens and Velten, 1994; Mullens and Luhring, 1998).:

Density-dependent sex determination of the parasitic nematodes is a general feature of mermithid life history. Parasitism of the host by multiple nematode individuals (termed superparasitism) reults in a higher proportion of the infective juveniles developing into males and, consequently, proportionally fewer females

In Heleidomermis magnapapula:

When midge larvae are parasitzed by a single nematode J2, most developed into adult females; parasitism by multiple J2 results in most developing into male adults.
Nematodes emerging from the midge larval host as adults and mated immediately; females are ovoviviparous; eggs hatch within the female uterus and juveniles emerge.
Occasionally the nematodes will carry over development into the adult, winged, host which may facilitate spread of nemtodes to new environments.
Higher nematode load reduces availability of host resources per parasite and the proportionally fewer and smaller nematode females may be less fecund
Higher nematode loads produced smaller adult male nematodes and increased and accelerated premature host death.
Larger midges supported higher parasite loads and a larger total volume of emerged nematode biomass.
Female nematode fertility was positively influenced by male nematode size, (Mullens and Luhring, 2023)

For Ecophysiological Parameters for this species, click	If species level data are not available, click for genus level parameters

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Ecosystem Functions and Services:

Population regulation of host species; biological control.. The type host, C. sonorensis, is a major vector of bluetongue virus to North American ruminants. However, since females of the nematode are ovoviparous, a resistant egg stage is not released into the environment, so distribution for bioloical control purposes may present a challenge.

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Management:

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References:

Blackmore, M. S. and Charnov, E. L. 1989. Adaptive variation in environmental sex determination in a nematode. American Naturalist 134:817-823. Christie, J. R. 1929. Some observations on sex in the Mermithidae. Journal of Experimental Zoology 53:59-76.

Mullens, B.A. and Luhring, K.A. 2023. Parasite load effects on sex ratio, size, survival and mating fitness of Heleidomermis magnapapula in Culicoides sonorensis. J. Nematology 55: e2023-1 r | DOI: 10.2478/jofnem-2023-0052

Mullens, B.A. and Luhring, K. A. 1998. Age-dependent parasitism of Culicoides variipennis sonorensis (Diptera: Ceratopogonidae) by Heleidomermis magnapapula (Nematoda: Mermithidae) and considerations for assessing parasite impact. Biological Control 11:49-57

Mullens, B. A. and Velten, R.K. 1994. Laboratory culture and life history of Heleidomermis magnapapula in its host, Culicoides variipennis (Diptera: Ceratopogonidae). Journal of Nematology 26:1-10.

Nickle W.R. 1972. A contribution to our knowledge of the Mermithidae (Nematoda). Journal of Nematology 4: 113-146.

Petersen, J. J. 1972. Factors affecting the sex ratio of mermithid parasites of mosquitoes. Journal of Nematology 4:83-87.

Poinar, G.O. 1983. The Natural History of Nematodes. Prentice-Hall, Englewood Cliffs. 323p.

Poinar, G.O and Mullans, B.A. 1987. Heleidomermis magnapapula n. sp. (Mermithidae : Nematoda) parasitizing Culicoides variipennis (Ceratopogonidae : Diptera) in California. Rev. de Nematologie 10:387-391