Laboratory culture of the free-living stages of Neomesomermis flumenalis, a mermithid nematode parasite of Newfoundland blackflies (Diptera: Simuliidae)

Abstract

Laboratory methods were developed for culturing the free-living stages of Neomesomermis flumenalis from field-collected blackfly larvae. The best results were obtained by placing 50 pairs of nematodes under xenic conditions in 500-ml containers containing about 450 ml of wet sand. With this method, 78.6% of the females introduced to culture reproduced. The influence of factors such as microorganisms, substrate, container volume, and sterility on culturing these mermithids is discussed. Differences were noted in the development of N. flumenalis from winter-breeding Prosimulium hosts and those from summer-breeding Simulium hosts. Parasites from Simulium developed nearly twice as fast as from Prosimulium hosts at 10 °C. Temperature studies showed that Simulium parasites were better adapted for higher temperature ranges (20 °C) but were more poorly adapted to lower temperatures (5 °C) than parasites from Prosimulium. The noted differences suggest two physiological strains of the same species, one developing in Simulium spp., the other in Prosimulium spp.