ABSTRACT
Field studies in Kenya and Mali investigated the prevalence of bacteria in the midguts of malaria vectors, and the potential relationship between gram-negative bacteria species and Plasmodium falciparum sporozoites. Midguts were dissected from 2,430 mosquitoes: 863 Anopheles funestus Giles and 1,037 An. gambiae s.l. Giles from Kenya, and 530 An. gambiae s.l. from Mali. An. funestus had a higher prevalence of gram-negative bacteria (28.5%) compared with An. gambiae collected in Kenya and Mali (15.4 and 12.5%, respectively). Twenty different genera of bacteria were identified by gas chromatography from 73 bacterial isolates from mosquito midguts. Pantoea agglomerans (Enterobacter agglomerans) was the most common species identified. There was no association between gram-negative bacteria in the midgut and P. falciparum sporozoites in field-collected An. gambiae s.l. and An. funestus. However, An. funestus females that harbored gram positive bacteria were more likely to be infected with sporozoites compared with those with no cultivable bacteria or gram negative bacteria in their midguts. Habitat-related variation in the prevalence of diverse types of bacteria in mosquitoes could influence malaria parasite development in mosquitoes and corresponding sporozoite prevalence.
Subject(s)
Anopheles/microbiology , Digestive System/microbiology , Insect Vectors , Malaria, Falciparum/epidemiology , Animals , Enterobacteriaceae/isolation & purification , Gram-Negative Bacteria/isolation & purification , Gram-Positive Bacteria/isolation & purification , Kenya , Mali , PrevalenceABSTRACT
Blood-feeding behavior and survivorship of individual Anopheles gambiae Giles females were observed daily in cohorts with either access to sugar (n = 76) or without sugar (n = 80). Individual mosquitoes were allowed to feed daily on an anesthetized mouse. Mosquitoes provided with sugar lived on average almost 3 d longer than females without sugar (19.0 versus 16.2 d). After stratification by age, mosquitoes in the youngest (5-12 d) and middle (13-19 d) age strata showed no differences in blood-feeding patterns relative to sugar availability. However, mosquitoes from the oldest age group and no access to sugar had more total blood feeds than long-lived females ( > or = 20 d) with access to sugar (9.8 versus 6.5). Furthermore, mosquitoes > or = 20 d old and without sugar available had a higher blood-feeding frequency than females that had sugar available (0.36 versus 0.25 blood meals per female per day). The enhanced blood-feeding capability among older sugar-deprived An. gambiae emphasized the close association between sugar-feeding and blood-feeding behavior and the potential consequences for the transmission of malaria parasites and other pathogens.
