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Molecular Entomology
31
Despite the effectiveness of these botanical pesticides,
they have not been generally accepted because
consumers find the effects posed by these botanical
pesticides on foods unacceptable. Such effects include
colour change, odour and change in taste of the treated
foods (Bagum et al., 2013). Furthermore, some of the
well known botanical pesticides have some cons that
are thwarting their widespread use. For example
nicotine isolated from a number of
Nicotiana
spp. is
insecticidal against wide range of stored product
insect pests but with a disagreeable odour and extreme
mammalian toxicity (Bagum et al., 2013). Rotenone is
also known for its toxic effect on fish as well as some
mammals because of its direct contact with the food
product it protects (Begum et al., 2013). Therefore an
acceptable method of application of these
bio-pesticides is required. In USA, pyrethrins and
piperonyl butoxide were effective and approved for
use as a treatment for insect-resistant packaging on the
outer layer of packages or with adhesives (Highland,
1991; Anwar et al., 2005). Neem oil extract was also
found to be effective against
R. dominica, Sitophilus
granarius, Tribolium castaneum
and
Trogoderma
granarium
when used to treat jute bag but its efficacy
was found to be greatly reduced after 60days of
storage (Anwar et al., 2005). Some adult insects of
stored products can pass through holes less than 1 mm
in diameter and their larvae can enter through even
smaller holes (Cline and Highland, 1981). Since the
effectiveness of many botanical oils that had been
claimed insecticidal on stored product insect pest
when used for treatment of packaging material of farm
produce have not been fully investigated, this research
therefore investigated the efficacy of jute bags treated
with oil of
E. aromatica,
one of the well known
bio-pesticides against
R. dominica
infestation on wheat.
Results
Effect of Jute bag treated with
E. aromatica
oil on
mortality of adult
R. dominica.
Table 1 showed the effect of oils of
E. aromatica-
treated jute bags
on mortality of adult
R. dominica.
At
all doses of
E. aromatica-treated
jute bags, more than
30% beetle mortality was recorded within 24 hours of
storage. Jute bags deep-soaked in 100ml of
E.
aromatica
achieved highest percentage of 82.36%
insect mortality within 24 hours of storage and its
effect was significantly (p< 0.05) different from other
bags. Also, within 48hours of storage only the jute
bags treated deep-soaked in 100ml oil of
E. aromatica
achieved 100% beetle mortality. Moreover, within 72
hours of storage jute bag treated with 8ml dose of
E.
aromatica
oil achieved complete insect mortality and
its effect was significantly (p<0.05) different from
others except jute bags deep-soaked in 100 mL of the oil.
Table 1 % mortality
R. dominica
on wheat seeds stored inside
E. aromatica-
treated jute bags at different doses
Doses (ml)
Mean % mortality ±S.E in hours
24
48
72
2
4
6
8
Deep-soaked
Solvent control
Untreated control
32.00±0.24
b
40.20±0.33
b
53.87±0.64
c
60.00±0.84
d
82.36±0.88
f
4.00±0.24
a
0.00±0.00
a
42.40±0.88
c
53.82±0.72
d
62.37±0.24
e
79.80±0.24
f
100.00±0.00
g
6.00±0.00
b
0.00±0.00
a
60.87±0.58
c
80.24±0.84
d
87.35±0.28
d
100.00±0.00
e
100.00±0.00
e
6.00±0.00
b
0.00±0.00
a
Note: Each value is the mean ±standard error of seven replicates. Mean followed by the same letters within the same column are not
significantly (P > 0.05) different from each other using New Duncan’s Multiple Range Test
Effect of
E. aromatica
treated jute bags on the adult
emergence of
R. dominica
infesting stored wheat.
The number of adult emergence of
R. dominica
on
stored wheat and percentage inhibition rate of the
E.
aromatica
treated jute bags were presented in Table 2.
All the oil treated jute bags were found to significantly
reduced or prevent the emergence of the adult beetle.
Only the 2 and 4ml
E. aromatica
treated jute bags was