First report of pathogenicity of Beauveria bassiana RBL1034 to the malaria vector, Anopheles gambiae s.l. (Diptera; Culicidae) in Cameroon

Abstract

Malaria vector control has been successfully achieved by the use of chemical insecticides. However, the evolution of insecticide resistance is rendering the standard approaches unsustainable. Biological
control agents such as entomopathogenic fungi are being considered for adult African malaria vectors. In the present study, laboratory trials were carried out to determine the pathogenicity of Beauveria
bassiana RBL1034 to adult Anopheles gambiae s.l. Both male and female A. gambiae were exposed to targets inoculated with dry conidia of B. bassiana RBL1034 and the infection/mortality rates and
relationship with concentration of conidia per inoculated target were determined. B. bassiana RBL1034 was observed to be pathogenic to both male and female A. gambiae with an average mortality of 80% in
the treated compared to 10% in the untreated group. The median lethal time (MLT50) in treated and untreated groups was 8 days and >10 days, respectively. Mosquito mortality increased as conidial
concentration increased. Fungal sporulation was observed in 87% of the mosquito cadavers in the treated group while no sporulation was observed in the control. This study indicates that dry conidia of
B. bassiana RBL1034 are pathogenic to adult A. gambiae and could be a potential biological control agent for these mosquitoes.