INTRODUCTION:
Despite their widespread usage, synthetic insecticides and larvicides are
harmful for controlling disease-causing mosquitoes owing to the development
of resistance. The leaves of
Eugenia astringens
,
Myrrhinium atropurpureum
, and
Neomitranthes
obscura
were collected from Marambaia and Grumari restingas.
The safety and larvicidal efficacy of their extracts were tested against
Aedes (Stegomyia) aegypti
L. and
Simulium
(Chirostilbia) pertinax
Kollar.
METHODS:
The dry leaves were subjected to static maceration extraction using 90%
methanol.
A. aegypti
and
S. pertinax
larvae were exposed to 7.5, 12.5, and 25.0 µL/mL of the extracts (n= 30).
The larvicidal activity after 24 h and 48 h, and the mortality, were
determined. The median lethal concentration (CL
50
) was estimated
by a Finney's probit model.
RESULTS:
M. atropurpureum
and
E. astringens
extracts exhibited the strongest larvicidal effects against
A.
aegypti
.
M. atropurpureum
extracts (25 µL/mL)
caused mortalities of over 50% and 100% after 24 h and 48 h, respectively
(CL
50
= 11.10 and 9.68 ppm, respectively).
E.
astringens
extracts (25 µL/mL) caused mortalities of 50% and
63.33% after 24 h and 48 h, respectively. High concentrations of
N.
obscura
extracts induced a maximum mortality of 46.66% in
A. aegypti
larvae after 48 h (CL
50
= 25 ppm).
The larvae of
S. pertinax
showed 100% mortality following
exposure to all the plant extracts at all the tested concentrations after 24
h.
CONCLUSIONS:
The extracts of
M. atropurpuerum
exhibited the strongest
larvicidal activity against
A. aegypti
. The larvae of
S. pertinax
were sensitive to all the extracts at all
the tested concentrations.