Effects of para-aminobenzoic acid, insulin, and gentamicin on Plasmodium falciparum development in anopheline mosquitoes (Diptera: Culicidae).

Anopheles gambiae Giles sensu lato (s.l.) and An. stephensi Liston were exposed as adults to para-aminobenzoic acid (PABA), human insulin, or gentamicin sulfate, an antimicrobial solution, to determine their effects on Plasmodium falciparum Welch development to the oocyst stage. For both mosquito species, concentrations of PABA from 0.001 to 0.05% had no effect on either oocyst infection rates or oocyst densities. At higher concentrations, PABA-fed mosquitoes had decreased oocyst infection rates when they were exposed after, but not before, experimental infections. Insulin-fed mosquitoes had significantly higher oocyst infection rates than controls and increased oocyst densities in both An. gambiae s.l and An. stephensi. The most dramatic impact on parasite development was observed for mosquitoes fed on gentamicin. For An. gambiae s.l. fed 0.05% gentamicin, oocyst infection rates were 3.7-fold higher than in controls, whereas oocyst densities were 5.7 times greater than in controls. Anopheles stephensi fed on diets of 0.1% gentamicin had 2.4-fold higher infection rates and increased oocyst densities. Concentrations of gentamicin above 0.1% had deleterious effects on mosquito survival and their ability to digest blood meals. These findings provide insight into how antibiotics, hormones, and metabolites may affect the development of P. falciparum in An. gambiae s.l. and An. stephensi.