First report of the infection of insecticide-resistant XXXX vector mosquitoes with an entomopathogenic fungus under field conditions.

@entity311 @entity20702 @entity313
BACKGROUND: Insecticide-resistant mosquitoes are compromising the ability of current mosquito control tools to control @entity311 vectors. A proposed new approach for mosquito control is to use entomopathogenic fungi. These fungi have been shown to be lethal to both insecticide-susceptible and insecticide-resistant mosquitoes under laboratory conditions. The goal of this study was to see whether entomopathogenic fungi could be used to infect insecticide-resistant @entity311 vectors under field conditions, and to see whether the virulence and viability of the fungal conidia decreased after exposure to ambient African field conditions. METHODS: This study used the fungus @entity20702 to infect the insecticide-resistant @entity311 vector @entity313 s.s (Diptera: Culicidae) VKPER laboratory colony strain. Fungal conidia were applied to polyester netting and kept under West African field conditions for varying periods of time. The virulence of the fungal-treated netting was tested 1, 3 and 5 days after net application by exposing An. gambiae s.s. VKPER mosquitoes in WHO cone bioassays carried out under field conditions. In addition, the viability of @entity20702 conidia was measured after up to 20 days exposure to field conditions. RESULTS: The results show that @entity20702 infection caused significantly increased mortality with the daily risk of dying being increased by 2.5   for the fungus-exposed mosquitoes compared to the control mosquitoes. However, the virulence of the @entity20702 conidia decreased with increasing time spent exposed to the field conditions, the older the treatment on the net, the lower the fungus-induced mortality rate. This is likely to be due to the climate because laboratory trials found no such decline within the same trial time period. Conidial viability also decreased with increasing exposure to the net and natural abiotic environmental conditions. After 20 days field exposure the conidial viability was 30%, but the viability of control conidia not exposed to the net or field conditions was 79%. CONCLUSIONS: This work shows promise for the use of @entity20702 fungal conidia against insecticide-resistant mosquitoes in the field, but further work is required to examine the role of environmental conditions on fungal virulence and viability with a view to eventually making the fungal conidia delivery system more able to withstand the ambient African climate.
