The efficacy of Alchornea cordifolia leaf powder was investigated against cowpea beetle, Callosobruchus maculatus on stored cowpea in the laboratory. The tested leaf powder was added as admixtures to 20 g of cowpea grains at the following rates of at 0 (control), 3, 4, and 5g % (w/w) while in the control treatment there was no plant material added. Each of the treatments was tested by exposing five pairs of adult beetles in a Completely Randomized Design (CRD) to assess oviposition deterrent and egg hatching suppression by the plant material. The results showed that oviposition and percentage egg hatched were significantly (P <0.05) suppressed on seeds treated with higher dosage level of the powder. Leaf powder with the concentration of 5g% (w/w)/20g cowpea seeds was most effective in suppressing oviposition and egg hatched. Thus, the result revealed that A. cordifolia leaf powder has oviposition deterrent and ovicidal properties and as such can be used as an alternative to synthetic insecticides for controlling C. maculatus infestation on stored cowpea grains. Therefore A. cordifolia leaf powder can be incorporated into traditional storage pest management as well as integrated pest management and it may strongly recommended in developing countries.

1. The Efficacy of Alchornea cordifolia Leaf Powder on Cowpea Beetle, Callosobruchus maculatus (Coleoptera: Bruchidae) as Oviposition and Egg Hatching Deterrent
The Efficacy of Alchornea cordifolia Leaf Powder on Cowpea
Beetle, Callosobruchus maculatus (Coleoptera: Bruchidae) as
Oviposition and Egg Hatching Deterrent
Koomson, Charles Kwesi
Department of Integrated Science Education, University of Education, Winneba, P.O. Box 25, Winneba, Central Region,
Ghana
Corresponding Author E-mail: charleskoomson@yahoo.co.uk
The efficacy of Alchornea cordifolia leaf powder was investigated against cowpea beetle,
Callosobruchus maculatus on stored cowpea in the laboratory. The tested leaf powder was added
as admixtures to 20 g of cowpea grains at the following rates of at 0 (control), 3, 4, and 5g % (w/w)
while in the control treatment there was no plant material added. Each of the treatments was
tested by exposing five pairs of adult beetles in a Completely Randomized Design (CRD) to assess
oviposition deterrent and egg hatching suppression by the plant material. The results showed
that oviposition and percentage egg hatched were significantly (P <0.05) suppressed on seeds
treated with higher dosage level of the powder. Leaf powder with the concentration of 5g%
(w/w)/20g cowpea seeds was most effective in suppressing oviposition and egg hatched. Thus,
the result revealed that A. cordifolia leaf powder has oviposition deterrent and ovicidal properties
and as such can be used as an alternative to synthetic insecticides for controlling C. maculatus
infestation on stored cowpea grains. Therefore A. cordifolia leaf powder can be incorporated into
traditional storage pest management as well as integrated pest management and it may strongly
recommended in developing countries.
Keywords: Alchornea cordifolia, Callosobruchus maculatus, egg hatching, oviposition deterrent, suppression
INTRODUCTION
Cowpea, (Vigna unguiculata (L) Walpers, Fabaceae), is an
important edible legume crop in many parts of the world
especially in tropical and subtropical regions. It is used as
human food and animal feed due to its high protein content
(Diouf, 2011). It is an annual herbaceous legume with
trifoliate leaves. It is a drought tolerant and short warm
weather crop well adapted to the drier regions where other
food legumes do not growing well (Singh, 1987). Cowpea
production is affected by insect pests and disease
infestations which lead to economic losses. Notably
among the many insects that attack this crop is Cowpea
beetle, Callosobruchus maculatus (F.) (Coleoptera:
Bruchidae) (Bamphitlhi, 2015). The cowpea beetle, is a
cosmopolitan field-to-store pest ranked as the principal
post-harvest pest of cowpea in the tropics (Caswel, 1981).
It causes substantial quantitative and qualitative losses
manifested by seed perforation and reductions in weight,
market value and germination ability of seeds (Obeng-
Ofori et al., 1997).
Efforts to develop insecticide-based techniques for
protecting grains in small traditional farm stores have only
been partially successful because of problems such as
high cost of synthetic insecticides and erratic supply due
to foreign exchange constraints (Obeng-Ofori et al., 1997).
Furthermore, the overuse of synthetic chemicals have led
to serious problems, including development of insect
resistant strains to insecticides, toxic residues on stored
grains, health hazards to grain handlers, food poisoning,
environmental pollution (Zettler and Coperus, 1990; White,
1995). These problems have stimulated research into
plants with insecticidal properties grown locally that are
readily available, effective, affordable, less poisonous and
less detrimental to the environment (Tierto, 1994). The
Research Article
Vol. 6(1), pp. 156-160, May, 2020. © www.premierpublishers.org. ISSN: 2326-7262
International Journal of Entomology and Nematology

2. The Efficacy of Alchornea cordifolia Leaf Powder on Cowpea Beetle, Callosobruchus maculatus (Coleoptera: Bruchidae) as Oviposition and Egg Hatching Deterrent
Koomson CK. 157
plants that are rich sources of compounds, have
insecticidal properties (Obeng-Ofori et al., 1997), like
Zanthoxylum xanthoxyloides (Udo, 2000) have been
successfully used to control insect pests. Alchornea
cordifolia is an important medicinal plant in African
traditional medicine and much pharmacological research
has been carried out into its antibacterial, antifungal and
antiprotozoal properties, as well as its anti-inflammatory
activities, with significant positive results (Agbor et al.,
2004). In recent years, several authors revealed that the
leaves, bark and roots of this plant was effective in
controlling the stored products insect pests through
contact toxicity and repellency activities (Koomson and
Oppong (2018) and Koomson et al., (2018)). The present
study, therefore, was undertaken to evaluate the efficacy
of the leaf powder of A. cordifolia as a suppressant of egg
hatchability and oviposition deterrent against C. maculatus
in stored cowpea.
MATERIALS AND METHODS
The research was carried out at the Integrated Science
Education Department laboratory of the University of
Education, Winneba, Central Region, Ghana, at a
temperature of 30 ± 2̊C and 75 ±5% relative humidity.
Insect Culture
Initial C. maculatus stock used for the experiment was
obtained from cowpea seeds that were bought from the
Mandela market at Agona Swedru in the Central Region of
Ghana. The cowpea grains were putted in different jars
covered with net and adult C. maculatus were introduced
into the jars. The jars were kept at room temperature in the
Integrated Science Education Department laboratory of
the University of Education, Winneba for the insects to
breed and multiply under favourable laboratory conditions
(temperature of 30±2°C, and relative humidity of 70±5%)
The moisture content of cowpea grain was adjusted to12
to 13% (Shiberu and Negeri, 2014). After three weeks of
oviposition, the parent beetles were sieved out after
oviposition to produce a steady and sufficient supply of
beetles of known age for experimental purpose (Adesina,
2012). Later the grains with jars were kept in the laboratory
for adult emergence while the emerging generation of
same age insects re-cultured at temperature of 30± 2°C,
and relative humidity of 70 ±5%. The F1 generation was
used for the experiment.
Collection and preparation of A. cordifolia plants
A. cordifolia plants were collected from the Gomoa
Otapirow area of the Central Region of Ghana. Leaves
were separated from the plant, rinsed in clean water to
remove sand and other impurities, air dried at room
temperature in the laboratory for 15 days, after which,
ground into very fine powder using an electric blender. The
powders were further sieved to pass through 1mm2
perforations. The powders were packed in plastic
containers with tight lids to ensure that the active
ingredients are not lost and stored it in the laboratory prior
to use.
Source of cowpea substrate
The un-infested cowpea (local variety) seeds were used in
the experiment, were procured from the Mandela market
at Agona Swedru in the Central Region of Ghana. The
seeds were properly sieved and handpicked, thus
ensuring that the only whole and uninfested seeds were
used (Olotuah et al., 2007; Adesina, 2012). The clean
seeds showed no visible signs of beetle eggs, presence of
adults or exit holes. Besides, the seeds were sterilized in
an oven at 50°C for 4 hours to kill any immature stage of
insect (if any) and allowed to cool for 1 hour before use
(Idoko and Adesina, 2013). Twenty gram each of the un-
infested cowpea seeds were weighed separately for
experiment and kept at room temperature. The experiment
was carried out in triplicate for each treatment.
Effect of Leaf Powder on Oviposition and Fecundity of
C. maculatus
The experiment was laid out in Randomized Compete
Block Design (RCBD) with three replications. Five (5)
paired sexed adult insects of 1-2 days old C. maculatus
were introduced into the a clean sterilized 250ml plastic
containers containing 20g of uninfected sterilized cowpea
seeds at 0, 3, 4, and 5g% (w/w) of A. cordifolia leaf powder,
while in the control treatment there was no plant material
added. The A.cordifolia leaf powder was weighed and
added to the cowpea grains in each jar and shaken well for
uniform coating. The sex of C. maculatus was determined
by the pattern of Iloba and Ekrakene (2006). The jars were
covered with muslin cloth and secured with rubber bands
as a ventilated lid. The number of eggs laid by the female
beetles on the seed coat was recorded on the 14th day
after the introduction of beetles to seeds; this was used to
calculate the percentage of egg hatching according to
Abdullahi et al. (2011) and the percentage reduction of egg
laying (Emman and Abass, 2010), as follows:
Percentage reduction of eggs laid
=
no. of eggs laid in control – no. of eggs on treated grains
no. of eggs laid in control
x
100
1
Egg hatching (%) =
no.of eggs hatched in each container
no.of eggs in each container
x
100
1
Statistical Analysis
Percentage data were transformed to square root of
arcsine to normalize the data before analysis. Data from
the 3 replicates of the experiment were pooled together
and subjected to one way Analysis of Variances (ANOVA).
Treatment means were separated using Least Significant
Differences (LSD) at 5% probability level (Gomez and
Gomez 1994).

3. The Efficacy of Alchornea cordifolia Leaf Powder on Cowpea Beetle, Callosobruchus maculatus (Coleoptera: Bruchidae) as Oviposition and Egg Hatching Deterrent
Int. J. Entomol. Nematol. 158
RESULTS
Effect of A. chordifolia leaf powder on oviposition and
fecundity of C. maculatus
The effect of A. chordifolia leaf powder on oviposition is
summarized in Table 1. The results showed that the
powders at all application levels significantly inhibited the
female C. maculatus from laying eggs on treated cowpea
seeds. The laying capacity gradually decreased with the
increase in the treatment dose of each powder. The
highest reduction in egg laying was observed with the 5g
powder treatment of 63.23% whereas 21.53% was
recorded in control. Statistically, there was a significant
difference between the tested concentrations compared to
control.
Table 1. Mean percentage reduction in number of eggs
laid by female C. maculatus
Treatment 20g/ cowpea Percentage reduction in
eggs laid
0 21.53 ± 2.3 d
3g 48.63 ± 2.1 c
4g 53.75 ± 0.5 b
5g 63.23 ± 1.7a
LSD 8.41
Effect of A. chordifolia leaf powder on Egg Hatching
The effect of A. chordifolia leaf powder on the egg hatching
capability of C. maculatus revealed that there was a
significant reduction in egg hatching. As the treatment
dose increases, the egg hatching capacity decreases. The
5g concentration gave the maximum reduction of 4.93%
as against 49.27% hatched eggs in control (Table 2).
Statistically, there was a significant difference between the
tested concentrations compared to control.
Table 2. Mean percentage of egg hatching of C. maculatus
from treated cowpea seeds
Treatment 20g/ cowpea Percentage egg hatching
0 49.27 ± 0.1 a
3g 17.21 ± 2.5 b
4g 10.39 ± 0.4 b
5g 4.93 ± 2.0 c
LSD 7.84
Significant difference is denoted by letters.
DISCUSSION
From the present study, the insecticidal activity of A.
chordifolia leaf powder is seen to be effective to varying
degrees in deterring oviposition and egg viability by C.
maculatus, and ultimately reduced the percentage seed
damage and weight loss due to infestation by the foregoing
insect pest (Adesina, 2012). This study also showed that
the A. chordifolia leaf powder significantly decreased the
number of eggs laid per female compared to that obtained
in the control. The marked decline in egg laying was
perhaps a consequence of the mild suppressing effect
exerted by these volatiles on the pulse beetles’ mating,
which is a decisive factor influencing the subsequent
number of eggs laid by the beetles (Adesina and Ofuya,
2015). Oviposition inhibition by C. maculatus was
observed by Ogunwolu et al. (1998) and Udo, (2000),
when treated Z. xanthoxyloides, a plant belonging to family
Lamiaceae. The decline in oviposition at higher doses of
plant powder have been attributed to the interruption of
vitellogenesis and damage to the egg chambers during
various life stages of C. maculatus (Pandey and Khan,
1998). Dhar et al., (1996) reported that oviposition was
possibly regulated by the volatile compounds absorbed
through cuticle. Oviposition deterrency may be due to the
changes induced in physiology and behavior of the insect
(Shifa et al., 2010)
It could be deduced that the complete inhibition in adult
emergence of C. maculatus by A. chordifolia leaf powder
might be due to total mortality observed at early days after
treatment. This resulted in inability of the insects to mate,
which deterred oviposition and hence, inhibited
emergence (Adesina and Ofuya, 2015). It is also reported
that the leaf powder might be toxic to the few eggs
deposited and as such led to reduced number of
emergence in grains treated with the powder concurring
with (Chudasama et al., 2015) that toxic substances
present in the leaf powder may enter into the egg through
chorion and suppressed further embryonic development.
Further, Ojo and Ogunyele, (2013) concluded that the non-
emergence of F1generation of insects treated with some
botanical powders could be as a result of high mortality of
adult insects, thus disrupting mating and sexual
communication as well as deterring females from laying
eggs and complete suppression of the developmental
stages of insects. Results have shown that there was
positive correlation between egg deposition and adult
emergence. This was clearly observed in untreated grains
where significant oviposition and adult emergence were
recorded. The outcome is corroborative with what has
already been previously reported (Iloba and Ekrakene,
2006). The egg mortality and the failure to hatch on seeds,
treated with the powder, were probably attributed to the
toxic component of the powder and also to the physical
properties, which caused changes in the surface tension
and the oxygen tension within the eggs (Adesina and
Ofuya, 2015). The ovicidal effect of the leaf powder on the
bruchid may also be explained in terms of asphyxiation by
blocking the major route of gas exchange between a thin
area of the chorion and outside (Credland 1992), which
ultimately reduced the emergence of the insects from the
treated seed (Copping and Menn, 2000). Results from this
study equally suggest that the plant material might
interfere with the normal embryonic development by
suppressing hormonal and biochemical processes. A
similar physiological inference was observed by Ofuya et
al., (1992). Studies on the effect of plant on the egg
hatching of pulse beetle are available. However, Adesina

4. The Efficacy of Alchornea cordifolia Leaf Powder on Cowpea Beetle, Callosobruchus maculatus (Coleoptera: Bruchidae) as Oviposition and Egg Hatching Deterrent
Koomson CK. 159
and Ofuya, (2015) found a significant effect on reduced
egg hatchability of C. maculatus when laid on seeds
treated with plant extracts and powder, respectively, at
different doses, which is in accordance with the present
study. This finding suggests that the A. chordifolia leaf
powder successfully inhibit egg hatching into the seed and
ultimately suppress the F1 progeny emergence. The
present study clearly indicates that A. chordifolia leaf
powder possess anti-oviposition and ovicidal activities that
can be employed in the management of C. maculatus
infestation on stored cowpea. Further studies are needed
to explore the metabolic target of the plant in the body of
the insect.
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Accepted 12 May 2020
Citation: Koomson CK (2020). The Efficacy of Alchornea
cordifolia Leaf Powder on Cowpea Beetle, Callosobruchus
maculatus (Coleoptera: Bruchidae) as Oviposition and
Egg Hatching Deterrent. International Journal of
Entomology and Nematology, 6(1): 156-160.
Copyright: © 2020 Koomson CK. This is an open-access
article distributed under the terms of the Creative
Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium,
provided the original author and source are cited.