Entomopathogenic fungi are potential candidates for use in integrated vector management. However, efficient delivery systems for these fungi need to be investigated. It is known that adult mosquitoes are attracted to dark surfaces, and therefore, black cotton cloths impregnated with Metarhizium anisopliae alone or in combination with the insecticide imidacloprid (IMI) were tested under laboratory conditions. Black cloths impregnated with fungus were also tested in large-cage trials under natural extradomicile conditions. Blood-fed Rockefeller and wild-type strain Aedes aegypti had higher levels of survival when compared with sucrose-fed counterparts following exposure to fungus-impregnated cloths. However, when blood-fed A. aegypti were exposed to a combination of M. anisopliae + IMI, the survival rates were statistically equal to those of sucrose-fed females. Large-cage trials showed significant decreases in A. aegypti survival following a minimum 12 h exposure of the mosquitoes to fungus-impregnated cloths. Increased exposure times results in further reductions in survival. The synergism between M. anisopliae and IMI resulted in reduced survival rates independent of feeding regime under laboratory conditions. Fungus-impregnated cloths tested under simulated field conditions, considered to be unfavourable for fungal infection, resulted in significant reductions in adult A. aegypti survival. We are currently testing the combined use of fungi and insecticides against blood-fed insects under simulated field conditions.
Significance and impact of the study: The use of fungus-impregnated cotton cloths is a promising point source application method for the control of adult Aedes aegypti, and this strategy could be incorporated into an integrated vector management programme aiming to reduce the incidence of dengue fever.
Keywords: blood feeding; dengue; fungus; insecticide; vector; virulence.
© 2013 The Society for Applied Microbiology.