2005 International Nuclear Atlantic Conference - INAC 2005
Santos, SP, Brazil, August 28 to September 2, 2005
ASSOCIAÇÃO BRASILEIRA DE ENERGIA NUCLEAR - ABEN
ISBN: 85-99141-01-5
CONTACT ACTIVITIES OF IRRADIATED PLANT EXTRACTS AGAINST
Sitophilus zeamais MOTSCHULSKY (COLEOPTERA: CURCULIONIDAE).
Marcos R. Potenza1; Valter Arthur2; Joana. D.Felicio1; Maria H. Rossi1; Massako. N.
Sakita3; Denise de F. Silvestre1; Dávinni. H. P. Gomes1
1
Instituto Biológico/APTA
Av. Conselheiro Rodrigues Alves, 1252
CEP 04014.002 – São Paulo/SP.
[email protected].
2
Centro de Energia Nuclear na Agricultura/USP
Av. Centenário, 303
CEP 13400-961, Piracicaba/São Paulo
[email protected].
3
Instituto Florestal
Rua do Horto, 931
CEP 02377-000, São Paulo/SP
[email protected]
ABSTRACT
The presence of Sitophilus zeamais causes damages by strong weight reduction, depreciation of commercial
value of the product and reduction of its nutritional value. The plant extracts have potencial substances for pest
control. This work aims at evaluating the effects of the aqueous, hexanic and ethanolic irradiated extracts of
Lycopersicon esculentum, Nephrolepis pectinata, Ruta graveolens and Ficus elastica, in order to identify new
substances for integrated pest management (IPM) and to observe possible effects of gamma radiation such as the
increase, reduction, activation of natural products to control pests. The effects on adults of S. zeamais aims that
were exposed by contact to the extracts were investigated. The samples were irradiated in a cobalt-60
gammacell 220 research facility. The vegetal extracts were exposed to doses of 2.5, 5.0, 7.5 and 10.0 kGy, at
room temperature. Gamma radiation increased the efficiency of ethanolic extract of L. esculentum to a 70.0%
level of mortality for S. zeamais adults at dose of 5.0 kGy. In contrast, it decreased the efficiency of the aqueous
extract of R. graveolens from 20.0% to 12.0%, 6.0% and 2.0%, at 5.0; 7.5 and 10.0 kGy, respectively.
1. INTRODUCTION
The society has demonstrated a increasing preoccupation with the impact from insecticides
on agricultural and urban environments. The usage of substances from vegetable such as oil
of native plants, medicinal plants, spices, herbs and forests essences have been evaluated with
this aim many times ago. Many essential oils from plants affect insects and can be used to
protect plants and control urban pests. Many families of plants have compounds with
insecticide activity, such as: Amaranthaceae, Amaryllidaceae, Annonaceae, Araceae,
Asteraceae, Chenopodiaceae, Compositae, Cruciferae, Cucurbitaceae, Euphorbiaceae,
Labiatae, Leguminosae, Malvaceae, Meliaceae, Piperaceae, Poaceae, Rosaceae, Rutaceae,
Solanaceae and others. The weevil Sitophilus zeamais is one of the main pests in stored
grains as corn, wheat, rice and sorghum, preferring the corn to ovipositor. The presence of S.
zeamais causes damages by strong weight reduction, depreciation of commercial value of the
product and reduction of its nutritional value [1]. By spreading fungus, and increasing
moisture and raising temperature of grains due to its metabolism, it contributes to the early
deterioration of stored products [2]. The plant extracts have potencial substances for pest
control [3, 4]. This work aims at evaluating the effects of the aqueous, hexanic and ethanolic
irradiated extracts of Lycopersicon esculentum, Nephrolepis pectinata, Ruta graveolens and
Ficus elastica, in order to identify new substances for integrated pest management (IPM) and
to observe possible effects of gamma radiation such as the increase, reduction, activation of
natural products to control pests. Thus, the effects on adults of S. zeamais that were exposed
by contact to the extracts were determined.
2. MATERIALS AND METHODS
2.1. Bioassay
The technique of filter paper impregnation was used in the bioassay used to investigate
mature individuals of S. zeamais. Each paper with 7 cm of diameter, received an aliquot of
1.0 mL of solution to 10% in acetone. To avoid losses of products by contact, the dishes of
paper were supported on pins points and the base was a small cork decreasing, this way, to
minimum the contact of the treated paper surface. After a little period of drying, the dish
papers treated in this way, were transferred to plates of Petri, and put to rest for 24 hours. To
confining of insects, inciting them to direct contact with treated surfaces with insecticides.
Glasses rings 4.5cm in diameter with covered with talc were used to co fine the insects and
prevent them from escaping the contact with the treated surface. As a safety measure to avoid
escape by flying, a transparent texture cover was also placed on the plattes strapped by elastic
bands. of height, treated previously with pure talc avoided that the weevils go up by rings
walls. Each plot was constituted by 20 adults of S. zeamais. To evaluate the responses was
adopted the criterion of mortality rate after 72 hours under exposition. Insects strongly
affected that exhibited entirely disordered movement with little or no leg motion were
considered dead.
2.2 Gamma Irradiation
The samples were irradiated in the 60Co gammacell facility located at Instituto de Pesquisas
Energéticas (IPEN) in the city of São Paulo. The vegetal extracts were exposed to doses of
2.5, 5.0, 7.5 and 10.0 kGy, in environment temperature. The gamma ray source gave a dose
rate of 6 kGy/h. The statistical approach uses was entirely casual and included with 5
repetitions. The results (based on the square root (root de x + 0,5)) were submitted to the “f”
and Tukey tests at the 5% confidence level.
3. RESULTS AND DISCUSSION
It was found that gamma radiation significantly increased up to 70% the efficiency of
ethanolic extract of L. esculentum in killing S. zeamais adults at dose of 5 kGy. The doses
used yielded mortality efficiency values ranging between 10 and 30% for the aqueous
extracts of L. esculentum. The gamma radiation in doses used, promote effciency of aqueous
extract of L. esculentum, between 12 and 20% (Tabel 1). The irradiated and no irradiated
aqueous extract of N. pectinata yielded a zero efficiency. The doses of 7.5 e 10 kGy cancel
the efficiency of hexanic and ethanolic extracts, and in the dose of 5 kGy both extracts
showed 36% of efficiency (Table 1). The gamma radiation showed adverse effect on the
aqueous extract of R. graveolens, decreasing its efficiency of 20% to 12%, 6% and 2% in
INAC 2005, Santos, SP, Brazil.
doses of 5; 7.5 and 10 kGy, respectively. In addition, a reduction in the efficiency of the
hexanic extract was also observed for doses higher than 5 kGy (Table 1). Significative effects
were not observed of gamma radiation on aqueous, hexanic and ethanolic extracts of F.
Elastica (Table 1).
Table 1. Evaluation of irradiated extracts to control of Sitophilus zeamais: extract type,
dose (kGy), mortality (mean*) and % of efficiency (% Ef.**).
São Paulo/SP, June-August of 2000.
Botanic specie
Dose of rate
Activity of source
Extract/Dose (kGy)
Aqueous -0.0
2.5
5.0
7.5
10.0
Hexanic -0.0
2.5
5.0
7.5
10.0
Ethanolic – 0.0
2.5
5.0
7.5
10.0
Ruta graveolens
Lycopersicon esculentum
6.06 kGy/h
6.20 kGy/h
31232 E10 Bq.
31931 E10 Bq.
Mean*
% Ef.**
Mean*
% Ef.**
2.00 bc
20.00
0.00
i
0.00
2.00 bc
20.00
1.60 defg
16.00
1.20 bcde
12.00
2.00 de
20.00
0.60 def
6.00
1.20
fgh
12.00
0.20
ef
2.00
1.40
efg
14.00
1.00 bcdef
10.00
2.00 de
20.00
0.80 cdef
8.00
2.40 cd
24.00
0.20
ef
2.00
3.00 bc
30.00
0.20
ef
2.00
1.40
efg
14.00
0.40 def
4.00
1.00
gh
10.00
2.40 b
24.00
1.00
gh
10.00
4.60a
46.00
2.40 cd
24.00
1.40 bcd
14.00
7.00a
70.00
0.40 def
4.00
1.20
fgh
12.00
0.80 cdef
8.00
1.00
gh
10.00
Fícus elastica
Nephrolepis pectinata
Aqueous -0.0
0.60 def
6.00
0.00
i
0.00
2.5
0.60 def
6.00
0.00
i
0.00
5.0
0.80 cdef
8.00
0.00
i
0.00
7.5
0.80 cdef
8.00
0.00
i
0.00
10.0
0.40 def
4.00
0.00
i
0.00
Hexanic -0.0
0.20
ef
2.00
1.60 defg
16.00
2.5
0.20
ef
2.00
1.80 def
18.00
5.0
0.40 def
4.00
3.60 b
36.00
7.5
0.20
ef
2.00
0.00
i
0.00
10.0
0.40 def
4.00
0.00
i
0.00
Ethanolic – 0.0
0.20
ef
2.00
0.60
h
6.00
2.5
0.20
ef
2.00
1.40 efg
14.00
5.0
0.20
ef
2.00
3.60 b
36.00
7.5
0.20
ef
2.00
0.00
i
0.00
10.0
0.20
ef
2.00
0.00
i
0.00
Control a - water
0.00
f
0.00
i
Control b - hexanic
0.00
f
0.00
i
Control c - ethanolic
0,00
f
0.00
i
C. V. (%)***
8.89
9.43
* The use of the same letters indicates that there is no significant difference among the figures at the f 5%
confidence level.
** Calculated by Abbott formule.
*** Changing coefficient.
INAC 2005, Santos, SP, Brazil.
4. CONCLUSIONS
The results indicated that gamma radiation significantly changed efficiency of the several
extracts tested in killing S. zeamais by contact. The findings range from complete
degradation (zero efficiency) or small reductions to significant increases in the capacity to
control that species.
REFERENCES
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Campinas: Fundação Cargill, pp. 228 (1995).
2. Athié, I.; Castro, M.F.P.M. de; Gomes, R.A.R.; Valentini, S.R.T. Conservação de grãos.
Campinas: Fundação Cargill, pp. 236 (1998).
3. Belmain, S.R.; Neal, G.E.; Ray, D.E.; Golob, P. Insecticidal and vertebrate toxicity
associated with ethnobotanicals used as post-harvest protectants in Ghana. Food Chem.
Toxicol., Vol. 39, pp. 287-291 (2001).
4. Golob, P.; Moss, C.; Dales, M.; Fidgen, A.; Evans, J. The use of spices and medicinals as
bioactive protectants for grains. FAO Agricultural Services Bulletin, n. 137 (1999).
INAC 2005, Santos, SP, Brazil.