Resistance of mosquitoes to insecticides is mainly attributed to their adaptation to insecticide-based
vector control interventions. Although pesticides used in agriculture have been frequently mentioned as an
additional force driving the selection of resistance, only a few studies were dedicated to validate this
hypothesis. The objective of this study was to investigate the effect of exposure of the malaria mosquito,
Anopheles gambiae
s.s. larvae for 72h to sub-lethal concentrations of the agrochemical mixture (pesticides,
herbicides and fungicides). Their subsequent tolerances were measured to deltamethrin (pyrethroid), DDT
(organochlorine) and bendiocarb (carbamate) currently used for vector control. The mean LC
50 was
determined and tolerance ratios for larvae exposed to agrochemical comparatively with unexposed larvae
were calculated and expressed as fold increased tolerance. Bioassays revealed a significant increase in larval
tolerance to detamethrin (1.83-2.86 fold), DDT (1.31-1.53 fold) and bendiocarb (1.14-1.19 fold) following exposure
to 0.1 μM and 1μM agrochemical mixture. The observed increased tolerance in this study is likely to be based on
metabolic resistance mechanisms. Overall, this study reveals the potential of agrochemicals to increase the
tolerance of mosquito larvae to chemical insecticides.
