The effects ofNosema algerae on the development ofPlasmodium yoelii nigeriensis inAnopheles stephensi

Experimental simultaneous infections ofAnopheles stephensi (Diptera: Culicidae) withNosema algerae (Microsporida: Nosematidae) andPlasmodium yoelli 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 ofNosema was 84.68%. At 14 days after infection withPlasmodium, the amount of sporozoites was examined; their mean reduction in eight experiments was 70%.