Insect Growth Regulatory, Moulting Disruption and Insecticidal Activity of Calceolaria talcana (Calceolariaceae: Scrophulariaceae) and Condalia microphylla Cav. (Rhamnaceae) - Natural Antioxidants and Biocides from Wild Medicinal Plants - page 220

(72.3 mg/g extract), whereas the concentra-
tion in the residue of methanol/water was
13.1 mg/g extract. The n -hexane did not
show the presence of this compound.

AI reduction in leaf consumption and this
was 96.7, 89.9, 89.7 and 88.3%, respec-
tively, while at 25 mg/ml the AI was 88.2,
85.6, 75.5 and 71.3% for verbascoside,
gedunin, ethyl acetate and methanol

extracts, respectively (Table 15.2).
The most active extract against D. mela-
nogaster was ethyl acetate, which showed
high deterrence power (Table 15.3), even at
concentrations of 25 mg/ml (75.1%), whereas
the percentage was reduced to moderate
effects for the methanol extract. Verbascoside
and gedunin show the highest effect with
89% and 81% at 10 mg/ml, respectively. At
concentrations greater than 10 mg/ml both
compounds produced 100% AI (Table 15.3).

15.5.3 Antifeedant activity

Some of the extracts of C. talcana showed
a high feeding dissuasive activity over the
S. frugiperda larvae in the choice assays
(Table 15.2). The consumption of leaves
treated with methanol, ethyl acetate and
MeOH-Yuc extracts were significantly lower
than for n -hexane and control, showing
high levels of feeding inhibition according
to the established values (Hassanali and
Lwande, 1989). Significant feeding inhibi-
tion occurs when the antifeedant index (AI)
is greater than 75% and moderate when it is
between 50 and 75%. At a concentration of
50 mg/ml, verbascoside, gedunin, ethyl acetate
and methanol extracts showed a significant

15.5.4 Insecticidal activity against

D. melanogaster

The results obtained in the tests of not-choice
for each one of the extracts of C. talcana

Table 15.2. Results obtained in antifeedant tests, using different extracts and compounds at different
concentrations of C. talcana on S. frugiperda l arvae.

AI(%)* of extracts AI(%) compounds

Concentration
( m g/ml) Aqueous Ethyl acetate Hexane Methanol Me-Yuc Verbascoside Gedunin

100 −78.6 100a 69.1e 100a 100a 100a 100a

50 −41.1 92.3b 55.6f 88.34c 77.9d 100a 89.9c

25 −30.4 89.7c 33.2g 71.30d n.d. 96.7b 85.6c

10 −9.3 75.5d 20.2g 67.45e n.d. 88.2c 74.5d

5 0 69.9e 19.9g 45.33f n.d. 78.9c 68.8e

*AI(%) = Antifeedant index = [(1−T/C) × 100]. n.d., not determined. The values followed by the same letter are not
significantly different. The significance level is p <95%.

Table 15.3. Results obtained in antifeedant tests, using different concentrations of extracts from
C. talcana on D. melanogaster larvae.

AI(%)* extracts AI(%) compounds

Concentration
( m g/ml) Aqueous Hexane Methanol Ethyl acetate MeOH-Yuc Verbascoside Gedunin

100 −78.9 92.31b 100a 100a 100a 100a 100a

50 −45.0 87.50c 93.67b 100a 85c 100a 100a

25 −31.5 49.00f 55.34f 75.1d n.d. 100a 98a

10 −10.8 −30.30 10.00g 56.5f n.d. 89c 81c

*AI(%) = Antifeedant index = [(1−T/C) × 100]. n.d., not determined. The values followed by the same letter are not
significantly different. The significance level is p <95%.