Journal of Mosquito Research 2015, Vol.5, No.11, 1-6
2
that are effective on each larval stage. It is in line with
this that this study was designed to study and report
on the effective dose of crude ethanol and water
extracts of mature green fruits and leaves of Endod on
larvae of
An. gambiae
in a laboratory set up.
1 Results
The experiment was conducted for a period of eight
months using a total of 84,240 larvae (L1s, L2s, L3s
and L4s). WHO threshold of >80% mortality was used
as standard to decide on the effectiveness of the various
doses against the exposed larvae. For L1s, concentration
of 20 mgs and 40 mgs of ethanol extracts of mature
green fruits of Endod from Eldoret and Nyando
respectively killed over 80% of the exposed larvae.
For aqueous extracts of Endod mature green fruits and
leaves of the shoot, mortality of over 80% was observed
for concentrations of 40mgs only irrespective of source
(Figure 1).
For L2s, concentrations of 20 mg and 40 mg of
ethanol extracts of mature green fruits from Eldoret
and Nyando killed over 80% of exposed L1s respectively.
Mortality of over 80% was observed for concentrations
of 40 mgs of extracts of leaves of the shoot and
midsection of Endod from Nyando and Eldoret
respectively. Concentrations of 20 mg and 40 mgs of
aqueous extracts of mature green fruits from Eldoret
and Nyando killed over 80% of exposed L2s
respectively (Figure 2).
For L3s, concentrations of 10 mg and 20 mg and
above of ethanol extracts of mature green fruits and
leaves of the shoot of Endod from Eldoret and Nyando
respectively killed over 80% of exposed L3s. The
same was observed for concentration of 40 mgs of
ethanol extracts of leaves of the midsection of Endod
(Figure 3). For the L4s, more than 80% mortality of
exposed larvae was observed for concentration of
10mgs and above for ethanol extracts of mature
green fruits irrespective of source (Figure 4).
Mortality of over 80% was observed for L1s and L3s
for ethanol and aqueous extracts respectively for
Neem while Deltamethrin killed all exposed larvae
irrespective of stage or concentration. The effects of
the extracts were considered significantly different at
p < 0.05 (Table 1) for all exposed larval stages.
2 Discussions
Ethanol extracts of mature green fruits of Endod at
higher concentrations killed all exposed aquatic stages
of
An. gambiae
. Mortality percentages however,
reduced with continued dilution. This trend was
similar to Ethanol extracts of Endod leaves although
observed mortalities were lower than that of fruit
extracts. Earlier the same trend had been reported for
powdered extracts of Endod on
An. gambiae
larvae
(Were, 2008). This demonstrates that extracts of
ethanol and water extracts of Endod have similar
efficacies as
Chenopodium ambrosioides
Linn (Jude et
al., 2013) and
Jatropha curcas
L (Zewdneh et al.,
2011) against
An. gambiae
and
Anopheles arabiensis
larvae respectively.
Extracts from both mature green fruits and leaves of
Endod were potent against
An gambiae
larvae though
potency of leaf extracts were lower than that of fruits.
Potency of the extracts also differed with the vertical
position of leaves on the Endod plant such that ethanol
extracts of leaves found at the shoot were more potent
than those found at the midsection of the plant. This
showed that the probable distribution of the bioactive
on Endod plant are such that fruits > leaves at the
shoot > leaves at the midsection.
Ethanol extracts of Endod parts were more toxic than
aqueous extracts of the same parts for all concentrations
against
An. gambiae
larvae. Solvent type used in
extraction had been demonstrated to determine
potency of extracted bioactives (Anupam et al., 2012)
as well as larviciding potency. This had been demonstrated
for
Solanum
xanthocarpum (Mohan et al., 2006),
Euphorbia tirucalli
(Singh et al., 2007),
Eucalyptus
globules (Maurya et al., 2007),
Citrullus colocynthis
(Sakthivadivel and Daniel, 2008),
Azadirechta indica
(Mgbemena, 2010) and
Solanum nigrum
(Raghavendra
et al., 2009).
Ethanol extracts of Endod parts sourced from Eldoret
were more potent than of the same parts sourced from
Nyando. This showed that geographical origin of the
plants played a role in the concentration and
distribution of bioactives within the plants (Anupam et
al., 2012). A similar observation had been made on
Endod parts (Were, 2008),
Citrus
sp,
Ocimum sanctum
and
Azadirechta indica
(Mgbemena, 2010) and
Jatropha
sp (Sakthivadivel and Daniel, 2008) just to
mention but a few.
