Repellency and Toxicity of Essential Oils
Repellency and Toxicity of Essential Oils
Repellency and Toxicity of Essential Oils
Repellency and toxicity of essential oils from the leaves and bark of Laurelia
sempervirens and Drimys winteri against Tribolium castaneum
Nelson Zapata a,b , Guy Smagghe a,
a
b
Laboratory of Agrozoology, Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium
Departamento de Produccin Vegetal, Facultad de Agronoma, Universidad de Concepcin, Avenida Vicente Mndez 595, Chilln, Chile
a r t i c l e
i n f o
Article history:
Received 17 December 2009
Received in revised form 1 June 2010
Accepted 4 June 2010
Keywords:
Tribolium castaneum
Essential oils
Safrole
Limonene
Methyl eugenol
Curcumene
-Pinene
a b s t r a c t
We report here on the repellent activity, as well as contact and fumigant toxicity, of four essential oils
extracted from the leaves and bark of Laurelia sempervirens and Drimys winteri against an important
stored-product insect pest: the red our beetle, Tribolium castaneum. The four oils tested had a very
strong repellent activity towards T. castaneum when tested in a lter paper arena test. After 4 h exposure
>90% repellency was achieved with L. sempervirens oils at low concentrations of 0.032 l/cm2 , while for
D. winteri oils concentrations of 310 times higher were needed to achieve this activity. Oils of both, L.
sempervirens and D. winteri, were found to be toxic towards T. castaneum when applied topically or by
fumigation. LD50 values by topical application of L. sempervirens oils were from 39 to 44 g/mg insect; for
D. winteri oils these were from 75 to 85 g/mg insect. By fumigation, LC50 values for L. sempervirens oils
were 1.61.7 l/l air, while these were 9.010.5 l/l air for D. winteri oils. In addition, with L. sempervirens
oils 50% of the tested beetles were killed at 100 <l/l air within 3.04.4 h, while with D. winteri oils the
LT50 values were 6.17.4 h. The results obtained are discussed in relation to the main constituents of the
oil extracts. In conclusion, the essential oils from the leaves and bark of L. sempervirens may be explored
as a potential natural insecticide for stored-product insect pests because of their high repellency and
insecticidal activities.
2010 Elsevier B.V. All rights reserved.
1. Introduction
The red our beetle, Tribolium castaneum Herbst (Coleoptera:
Tenebrionidae), is one of the most widespread and destructive
stored-product pest throughout the world. Beetles and larvae
feed on a very wide variety of dry vegetable substances, such
as milled cereal products (Rees, 2004). The application of various synthetic insecticides and fumigants to grain storage over the
years has led to a number of problems, including the development
of insecticide resistance in stored grain insect pests (Lorini and
Galley, 1999; Sousa et al., 2009). In addition, the increasing public
concern over pesticide safety and possible damage to the environment has resulted in increasing attention being given to natural
products for the control stored pests (Rajendran and Sriranjini,
2008).
In this context, many plant products have been evaluated for
their toxic properties against different stored grain pests, especially in the form of essential oils (Regnault-Roger, 1997; Rajendran
and Sriranjini, 2008). Essential oils are composed of complex
406
To determine the fumigant toxicity of the oils and the exposure time required to kill 50 and 90% of the insects (LT50 and
LT90 values), lter papers (Whatman #1, cut into 2 cm diameter
pieces) were impregnated with an appropriate concentration of
essential oils extracted from the leaves and bark of L. sempervirens
(10100 l/l air) or D. winteri (25600 l/l air) without using
any solvent. The impregnated lter paper was then attached to
the undersurface of the screw cap of a 30 ml glass vial. The lids
were screwed tightly onto the vials, each of which contained ten
unsexed adults of T. castaneum. Six replicates were prepared for
each treatment including a control without any essential oil, and
were kept under the same environmental conditions described
for the rearing. Mortality was recorded after 2, 4, 6, 10 and 24 h
of exposure to the essential oils. Time-mortality data for each
experiment were analyzed via the method developed by Finney
(1971) with time as the explanatory variable.
Another experiment was designed in order to determine the 50
and 90% lethal concentration. Filter paper disks (Whatman #1 of
8 cm diameter) were impregnated with essential oils of L. sempervirens (0.58.0 l/l air) or D. winteri (4.032.0 l/l air). The treated
paper disk was then attached to the undersurface of the screw lids
of a 1500 ml glass ask. The lids were screwed onto the asks, each
of which contained ten unsexed adults. Replicates and incubation
conditions were the same described for the previous experiment.
Mortality was recorded after 24 h of exposure, LC50 and LC90 values
were calculated.
407
Table 1
Repellent activity of essential oils from leaf and bark of Laurelia sempervirens and
Drimys winteri against Tribolium castaneum at different exposure time.
Dose (l/cm2 )
Repellency (%)
2h
4h
43.34 6.67 a
56.67 4.17 a
63.34 6.15 b
70.00 4.47 b
76.67 3.33 b
93.34 4.22 c
(F = 27.98; df = 5,30; P < 0.001)
46.67 11.16 a
60.00 8.03 ab
66.67 8.43 abc
76.67 6.15 bcd
83.34 3.33 cd
96.67 3.33 d
(F = 6.22; df = 5,30; P = 0.001)
36.67 3.33 a
43.34 6.15 ab
56.67 3.33 bc
70.00 4.47 cd
76.67 3.33 d
83.34 6.15 d
(F = 16.28; df = 5,30; P < 0.001)
50.00 4.47 a
63.34 6.15 ab
66.67 4.22 b
83.34 6.15 c
86.67 6.67 c
96.67 3.33 c
(F = 10.68; df = 5,30; P < 0.001)
53.34 4.22 a
66.67 8.43 b
73.34 4.22 b
90.00 4.47 c
100.00 0.0 c
100.00 0.0 c
(F = 17.35; df = 5,30; P < 0.001)
Means within the same column followed by the same letter are not signicantly
different. ANOVA, LSD (P > 0.05).
Table 2
LD50 and LD90 values of essential oils from leaves and bark of Laurelia sempervirens and Drimys winteri applied by contact against Tribolium castaneum.
Essential oil
Slope SE
df
L. sempervirens
Leaf
Bark
44.05 (39.0049.05)
38.94 (34.2943.11)
102.49 (87.62127.98)
78.7 (68.9595.53)
3.49 0.38
4.19 0.52
10.37
13.95
40
40
D. winteri
Leaf
Bark
84.05 (77.4190.75)
75.14 (69.3580.82)
162.47 (145.67187.40)
132.29 (120.45149.23)
4.48 0.39
5.21 0.46
18.82
14.71
40
40
408
Table 3
LT50 and LT90 values of essential oils from leaves and bark of Laurelia sempervirens applied as a fumigant against Tribolium castaneum.
Oil concentration (l/l air)
Slope SE
df
Leaf oil
10
20
40
60
80
100
9.14 (8.4110.00)
7.99 (7.338.71)
6.48 (5.967.00)
5.82 (5.316.32)
5.07 (4.575.56)
3.96 (3.494.41)
18.7 (16.1522.95)
16.67 (14.4920.21)
12.27 (10.9814.23)
11.43 (10.2213.24)
10.93 (9.6712.80)
9.17 (8.0610.83)
4.13
4.01
4.62
4.37
3.84
3.51
0.40
0.38
0.43
0.39
0.34
0.32
22.31
16.27
10.51
16.20
15.25
26.54
40
40
40
40
40
40
Bark oil
10
20
40
60
80
100
8.8 (8.149.55)
7.47 (6.928.04)
6.62 (6.127.12)
5.6 (5.116.09)
4.06 (3.604.50)
3.42 (3.043.79)
16.84 (14.7620.21)
13.68 (12.2115.98)
11.9 (10.7213.71)
11.01 (9.8412.74)
8.91 (7.8910.41)
6.81 (6.097.85)
4.55
4.87
5.03
4.36
3.76
4.29
0.43
0.46
0.47
0.38
0.34
0.40
23.33
14.31
25.04
27.58
12.03
11.28
40
40
40
40
40
40
df
Slope SE
Leaf oil
25
50
100
200
400
600
11.18 (10.2412.34)
8.77 (8.139.50)
6.66 (6.057.32)
4.87 (4.325.42)
4.49 (3.974.99)
3.89 (3.434.33)
23.46 (19.9729.40)
16.42 (14.4619.60)
15.29 (13.2318.57)
12.2 (10.5514.77)
10.98 (9.5614.13)
8.91 (7.8411.19)
3.98
4.71
3.55
3.21
3.30
3.56
0.38
0.45
0.32
0.29
0.30
0.33
16.94
12.70
23.26
22.84
22.10
23.58
40
40
40
40
40
40
Bark oil
25
50
100
200
400
600
13.02 (11.9714.37)
9.25 (8.689.90)
6.84 (6.277.44)
4.59 (4.125.04)
3.86 (3.464.24)
2.78 (2.443.10)
24.25 (20.8630.00)
15.04 (13.5217.48)
13.97 (12.3116.57)
9.51 (8.4811.00)
7.53 (6.758.63)
5.32 (4.736.18)
4.74
6.08
4.13
4.05
4.41
4.56
0.46
0.62
0.38
3.56
0.40
0.47
12.49
20.29
18.44
15.46
18.70
9.16
40
40
40
40
40
40
Slope SE
df
1.66 (1.351.99)
1.63 (1.322.00)
8.44 (6.3512.56)
8.61 (6.4312.98)
1.81 0.18
1.77 0.18
16.34
19.86
34
34
8.96 (7.5410.36)
10.45 (9.1611.71)
31.54 (25.3543.32)
24.86 (21.4130.43)
2.35 0.26
3.40 0.34
10.54
15.25
34
34
air, respectively. While the 95% ducial limits for the same lethal
concentrations for the D. winteri leaves and bark oils were 7.54 and
11.71 l/l air, and 21.41 and 43.32 l/l air.
4. Discussion
A total of 16 and 20 compounds have been identied from the oil
of the leaves and bark of L. sempervirens, respectively (Zapata et al.,
2010). The main constituents in the leaves oil were safrole (82.41%)
and limonene (7.76%). Safrole was also the main constituent in oil
from bark (49.71%), and methyl eugenol (18.04%) was the second
main constituent, followed by limonene (13.49%). In the essential
oils extracted from the leaves and bark of D. winteri 32 and 16 compounds were identied, respectively. The main constituents in the
D. winteri leaves oil were more diverse with -curcumene (11.12%)
as a major compound and then a group of 5 compounds consisting
of 69%, i.e. limonene + myrcene, limonene, trans-caryophyllene, -
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