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International Journal of Horticulture 2014, Vol.4, No.6, 24
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such as ashes, plant powder and latex, extracts and oils,
which are cheaper, safe, biodegradables and eco-friendly
(Adedire and Ajayi, 1996, Adedire et al., 2011; Ileke and
Oni, 2011; Ojo and Ogunleye, 2013a; 2013b). Farmers
and researchers often claim successful use of plant
materials in insect pest control including vegetable oil,
spices and plant powders or extracts (Isman, 2006;
Rajapakse and Van Emden, 1997). Their main advantage
is that these materials are cheap and readily available to
farmers and small scale industries in form of crude or
partially purified extracts. It was reported that when
mixed with stored-grains; leaf, bark, seed powder or oil
extracts of plants reduced oviposition rate and
suppressed adult emergence of bruchids and also
reduced seed damage rate (Onu and Aliyu, 1995, Shaaya
et al., 1997; Keita et al., 2001, Ojo and Ogunleye,
2013b). For these reasons, there is need to search for
other plants which could comparably contend with
synthetic chemical insecticides since tropical region of
the world including Nigeria, are well endowed with
numbers of plant species that could have entomocidal
properties. The cheese wood,
A. boonei
De Wild
(Apocyanaceae) is an African large evergreen deciduous
crude medicinal tree that shed its leaves annually. The
plant is about 45 m tall and 1.2 m in diameter. It possess
roots, stems, barks, leaves, fruits, seeds, flowers, and
latex, which are claimed to have medicinal values in
some cultures in African countries. The plant stem bark
and its latex are applied in traditional medicine for
treating many diseases (Moronkola and Kunle, 2012).
Therefore, this study investigated the phytochemical
vetting and effectiveness of
A. boonei
oil in the
management of cowpea bruchid,
C. maculatus
.
1 Results
1.1 Toxicity of
A. boonei
oils obtained by Soxhlet
method on mortality of adult
C. maculatus.
Table 1 presented the effects of
A. boonei
oils obtained
by soxhlet method on adult mortality of
C. maculatus
after 4 of application. The petroleum ether oils of
A.
boonei
stem bark at rate 2%, 3% and 4%/20g of cowpea
seeds completely caused 100% mortality of adult
C.
maculatus
after 4 days of application. This is followed
by oil of
A. boonei
leaf caused 100% adult cowpea
bruchid at rate 4% while the least toxic was oil of
A.
boonei
root evoked 95% adult
C. maculatus
at rate 4% /
20g of cowpea seeds after 4 days of application. The
results obtained on oils treated seeds is significantly
difference from solvent treated and untreated cowpea
seeds. The stem bark oils completely caused 100% adult
mortality of
C. maculatus
at all tested concentrations
after 4 days of application.
Table 1 Mortality of adult
C. maculatus
in cowpea seeds treated with 4%
A. boonei
oils after 4 days of application
Oils/Concentration (%)
1
2
3
4
Leaf
60.00±4.08
d
800.00±4.08
d
95.00±2.89
c
100.00±0.00
c
Stem bark
85.00±2.89
d
100.00±0.00
d
100.00±0.00
c
100.00±0.00
c
Root
42.50±7.50
d
52.50±7.50
c
82.50±7.50
d
95.00±2.89
d
Control (PT)
12.50±3.74
b
15.00±2.89
b
22.50±7.50
b
22.50±7.50
b
Control (NSNO)
0.00±0.00
a
0.00±0.00
a
0.00±0.00
a
0.00±0.00
a
Note: Each value is a mean+standard error of four replicates. Means followed by the same letter along the column are not significantly
different (P>0.05) using New Duncan’s Multiple Range Test; Keys: PT: Petroleum alone treated; NSNO: No oil, no solvent
1.2 Effect of
A. boonei
stem bark oils obtained by
Soxhlet method on oviposition and adult emergence of
adult
C. maculatus
Table 2, Table 3, Table 4 and Table 5 presented the
effects of
A. boonei
oils obtained by soxhlet method on
oviposition and adult emergence of adult
C. maculatus
after 4 of application. There was no adult emergence of
C. maculatus
in seed treated with Stem bark oil at all
levels of concentration tested after 4 days of application
(Tables 2, Table 3, Table 4; Table 5). Similar result was
also obtained for oil of
A. boonei
stem root at rate 4%
after 4 days of treatment. The results obtained on
cowpea seeds treated with oils were significantly
different from solvents treated cowpea seeds (Tables 2,
Table 3, Table 4; Table 5)