The effects of Nosema algerae on the development of Plasmodium yoelii nigeriensis in Anopheles stephensi.

Experimental simultaneous infections of Anopheles stephensi (Diptera: Culicidae) with Nosema algerae (Microsporida: Nosematidae) and Plasmodium yoelii nigeriensis under standardized laboratory conditions showed partial suppression of the malaria parasite. At 9 days after an infective bloodmeal, the oocysts in the midgut were counted; 12.1%-66.6% of the double-infected mosquitoes exhibited no oocysts, whereas only 4.5%-12% of the control group showed no oocysts. The mean reduction in oocyst numbers under the influence of Nosema was 84.68%. At 14 days after infection with Plasmodium, the amount of sporozoites was examined; their mean reduction in eight experiments was 70%.