Research article

Ecdysteroids and oocyte development in the black fly Simulium vittatum

Rafael Noriega² , Frank B Ramberg¹ and Henry H Hagedorn¹

¹  Department of Entomology and Center for Insect Science University of Arizona, Tucson, AZ, USA

²  University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15216, USA

author email corresponding author email

BMC Developmental Biology 2002, 2:6doi:10.1186/1471-213X-2-6

Published:	24 April 2002

Abstract

Background

Oocyte development was studied in the autogenous black fly, Simulium vittatum (Diptera, Nematocera), a vector of Onchocerca volvulus, the causative agent of onchocerciasis.

Results

Oocyte growth was nearly linear between adult eclosion and was complete by 72 hours at 21°C. The oocyte became opaque at 14 hours after eclosion indicating the initiation of protein yolk deposition. The accumulation of vitellogenin was measured using SDS-PAGE. The density of the yolk protein bands at about 200 and 65 kDa increased during the first and second days after eclosion. The amount of protein in the 200 kDa band of vitellogenin, determined using densitometry, rapidly increased between 12 and 25 hours after eclosion. Ecdysteroid levels were measured using a competitive ELISA. Ecdysteroid levels increased rapidly and subsequently declined during the first day after eclosion.

Conclusion

These data show a correlation between the appearance of vitellogenin in the oocyte, and the rise in ecdysteroids. A possible relationship to molting of the nematode, Onchocerca volvulus, is discussed.