Fresenius Environmental Bulletin, cilt.30, sa.11, ss.11938-11941, 2021 (SCI-Expanded)
Aedes aegypti L. (Diptera: Culicidae) is one of
the most dangerous mosquito species in the world.
This species transmits pathogens of many diseases
that cause more than ten thousand human deaths to
occur annually worldwide. For the control of Ae. aegypti, different types of insecticide groups are widely
used but this mosquito developed resistance to many
of these insecticides. Lichens are special organisms
that include fungi with algae and/or cyanobacteria.
They can produce various kinds of secondary metabolites that have biological activities on different
pests. Of these metabolites; atranorin and usnic acid
are the most known and common metabolites extracted from many lichen species. In this research, it
was aimed to investigate the toxic effects of (-)-usnic
acid and atranorin on larvae of Ae. aegypti. Aedes
aegypti late second and early third instar larvae were
used in toxicity assays. Stock solutions of atranorin
and (-)-usnic acid were prepared by dissolving of
metabolite in acetone. Ten larvae of Ae. aegypti were
released to the test solution and the mortalities were
recorded at 24 h intervals during 120 h and the percentage mortality rates were obtained from the average of four replicates. Lethal concentrations were
calculated using probit analysis. According to results, both metabolites caused high mortalities and
the median lethal concentrations (LC50) of the
atranorin and usnic acid were determined as 3.3 ppm
and 3.8 ppm, respectively at 120 h. Atranorin, at 10
ppm concentration, caused 100% mortality while usnic acid at 10 ppm concentration caused 61.3%. Lichens produce many secondary metabolites and we
suggested that these metabolites could be used for
development of new mosquicidal agents.