Plasmodium falciparum is primarily transmitted by Anopheles gambiae . Malaria caused
by Plasmodium falciparum is a major public health issue in western Kenya and sub-Saharan
Africa, accounting for 90% of malaria deaths. The primary methods of malaria prevention
are indoor residual spraying and the use of insecticide-treated nets. These tools
face challenges such as mosquito resistance to insecticides as well as their toxic
effect to the non-target organism, therefore this study aims to explore the application
of lichen secondary metabolites as potential oral biological insecticides by assessing
mosquito mortality in varying concentrations. Lichen secondary metabolites were extracted
from Cladonia foliacea thalli. Bioassay experiments were conducted on A. gambiae Kisumu
strain mosquitoes. Mortality rates were measured after ingesting sugar bait and lichen
extracts in different concentrations. Three test replicates and negative control were
used, with mortality measured after 4, 24, 48, and 72 hours. Analysis using three-way
analysis of variance with twoway interactions was performed using R program to determine
the effect of different lichen extract concentrations, time of exposures and mosquito
sex on mortality. Our results showed that the ingestion of C. foliacea extract at
50 mg/ml and a post-exposure period of 24 to 48 hours had a maximum effect on the
mortality rate of targeted male and female A. gambiae . No statistical difference
was found between male and female mosquitoes in mortality. Our study confirms firstly
that the extract of C. foliacea is a promising oral toxic agent against adult malaria
vector A. gambiae .
