LAUSR

BACKGROUND Exposure to inorganic fertilizer is common for the major malaria vector Anopheles arabiensis, which is closely associated with agricultural activities. The aim of this study was to understand if insecticide susceptible and resistant individuals respond to fertilizer exposure in the same manner. Two laboratory strains; SENN, an insecticide susceptible strain and SENN-DDT, an insecticide resistant strain selected strain selected from SENN, were used in this study. Both strains were exposed to one of three concentrations to a combination Nitrogen-Phosphorus-Potassium (NPK) inorganic fertilizer, as well as nitrogenous (Urea), phosphorus (Superphosphate) and kaelic (Potassium chloride-KCl) elemental fertilizer. The time-to-pupation was monitored, adult longevity was assessed and insecticide tolerance of adults was determined. The effect of elemental fertilizers on ovipositioning site choice was also assessed. RESULTS For both strains, urea increased the number of eggs laid, while superphosphate resulted in a significant decrease in egg-laying. Larval NPK exposure decreased time-to-pupation in the SENN strain but not SENN-DDT. Urea exposure increased time-to-pupation in both strains, while KCl decreased time-to-pupation in both strains. Larval NPK exposure only affected adult male longevity at high concentrations. Larval exposure to NPK and KCl resulted in increased insecticide tolerance in both strains, with variable efficacy from strain to strain. CONCLUSION Exposure to inorganic fertilizers has a greater effect on insecticide susceptible An. arabiensis as compared to resistant strains, where the primary advantage is increased insecticide tolerance. These data also demonstrate that larval fertilizer exposure can affect fecundity and fertility, and alter the life histories of adult An. arabiensis. This article is protected by copyright. All rights reserved.