Adult worms typically live from 8-15 years in human hosts, and microfilariae can live up to 2 years. Adults can be found grouped together in various regions of the human body, with groups containing about half as many males as females. The males move from group to group, inseminating the females.
Females may produce a phermomone to attract males. The male coils around a female with his curved area over the female genital pore. The gubernaculum, made of cuticle tissue, guides spicules which extend through the cloaca and anus. Males use spicules to hold the female during copulation. Nematode sperm are amoeboid-like and lack flagella.
Fertilized eggs develop into live microfilariae in 3-12 weeks, and the females release the microfilariae into the host body. A single female worm may release 1300-1900 microfilariae per day for 9-11 years.
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); ovoviviparous
There is no parental investment beyond the time the female releases the microfilariae.
Parental Investment: pre-fertilization (Provisioning); pre-hatching/birth (Provisioning: Female)
- Barnes, R. 1987. Invertebrate Zoology. Orlando, Florida: Dryden Press.
- Burnham, G. 1998. Onchocerciasis. Lancet, 351: 1341-1346.
- Richards, F., D. Hopkins. 2000. Programmatic Goals and Approaches to Onchocerciasis. Lancet, 355: 1663-1664.
- Roberts, L., J. Janovy, Jr. 2000. Foundations of Parasitology, Sixth Edition. New York: Mc Graw Hill.