An improved method of mass culturing of Romanomermis iyengari, a mermithid nematode parasite of mosquito larvae

Abstract

An attempt was made to develop an alternative method of mass culturing for R. iyengari instead of the usual sand culture method. Fifty pairs each of post-parasitic juveniles were seeded in moist sandbed and beakers containing tap water and distilled water and examined for exsheathing, egg-laying and egg-hatching. All post-parasitic juveniles in the moist sandbed had moulted by 7th day whereas in tap water and distilled water it lasted up to 11th day. Maximum numbers of eggs were observed on day 14 in sandbed (15/ml), day 16 in tap water (24/ml) and day 29 in distilled water (28/ml). The preparasites obtained from moist sandbed, tap water and distilled water did not exhibit any difference in their infectivity to mosquito larvae. The eggs of the nematode obtained from a culture in distilled water maintained at 30 +/- 2 degrees C for 60 days, when treated with CO2 (18 to 556 ppm) showed enhanced rate of egg hatching (73-98% compared with 11.5% in the untreated ones). CO2 treatment did not affect the infectivity of the preparasites that hatched from the CO2-treated eggs.