Article Type: Research Article Article Citation: Okonkwo Nnaemeka
Joe, Ejiofor MaryGeraldine Ebele, Iwuagwu
Christian Chukwunenye, Aguwa
Uwaoma Otuodichimma, and Ibeabuchi
Uko. (2020). PROTECTANT EFFICACY OF DENNETIA
TRIPETALA BAK. (F) (ANNONACEAE) EXTRACTS AND DELTAMETHRIN AGAINST SITOPHILUS
ZEAMAIS MOTSCH (COLEOPTERA: CURCULIONIDAE) IN STORED MAIZE. International
Journal of Research -GRANTHAALAYAH, 8(6), 10-14. https://doi.org/10.29121/granthaalayah.v8.i6.2020.203 Received Date: 04 May 2020 Accepted Date: 21 June 2020 Keywords: D. Tripetala Deltamethrin S. Zeamais Stored Maize The use of plant products has shown great potentials as alternatives to synthetic insecticides. The present studies investigated the efficacy of Dennetia tripetala and Deltamethrin as grain protectants against adult Sitophilus zeamais in stored maize. Acetone extracts of D. tripetala and Deltamthrin 12.5EC were evaluated in the laboratory based on insect mortality, progeny production and grain damage. Five concentration levels of each toxicant were prepared including 20mls, 15mls, 10mls, 5mls and 1ml for D. tripetala and 1ml, 0.5ml, 0.25ml, 0.1ml and 0.01ml for Deltamethrin. Controls with no toxicants were included. The design of the experiment was a CRD and each repeated 4 times. Twenty grams of insect-free maize were measured into each replicate vial and infested with ten, 1-5-days old adult insects. Mortality was recorded at 12, 24, 48- and 72-hours post-treatment. After 35 days, progeny production and number of damaged grains were recorded. Data obtained were statistically analyzed using SPSS version 13. The results indicated that Deltamethrin was more toxic than Dennetia tripetala, however, at 10mls-20mls, D. tripetala showed moderate toxicity against S. zeamais. Comparative mortalities of the two toxicants indicated that Deltamethrin was significantly (P < 0.05) more toxic than D. tripetala at all levels. The studies however, revealed that the application of D. tripetala in controlling S. zeamais could be effective at higher concentrations. Therefore, it was suggested that D. tripetala should be applied at higher concentrations for effective control of maize weevil.
1. INTRODUCTIONMaize belongs to the Family Poaceae. It is an important cereal crop in Nigeria, where it serves as major staple food component of their diet. The harvested crop is attacked by a wide range of insect pests including, beetles and moths (Ogungbite and Oyeniyi, 2014). The weevil, Sitophilus zeamais Motsch (Coleoptera: Curculionidae) is a major insect pest of maize grain in Nigeria and other parts of the world, causing severe losses incurred in stored maize annually (Nwana, 1993). In recent years, controlling many of these destructive insects has profoundly relied on the use of synthetic chemical (Akinkurolere, 2007) which have been reported to have many consequence that impede their widespread use nowadays. Public awareness of adverse side effects of the synthetic insecticide has called for an urgent need to look for safer alternative that could comparably contend with chemical insecticide in action. In order to limit the use of these synthetic chemical insecticide, research studies have been focused on plant kingdom as a new tool of controlling insect pest of stored products (Ogungbite and Oyeniyi, 2014). 2. METHODOLOGYAdult Sitophilus
zeamais were obtained from the infested stocks of
maize purchased from Nise market, Awka,
Anambra State, Nigeria. The weevils were introduced into 2 different containers
each containing 700 g of clean maize grains var. Yellow Jos Mangu.
The weevils were allowed to oviposit and multiply for 2 months until required
for experiment. Matured adult weevils were removed and the culture returned to
the container for further outbreeding. Adults that were 1-5 days old were used
for the experiment. Fresh fruits
of Dennetia tripetala
weighing 600g were obtained from Eke Awka Market
Anambra State, Nigeria. The seeds were extracted and sun-dried for 4 days,
after which they were pulverized with an electric Blender. One hundred grams of
the pulverized sample was added to 250mls of Acetone (Analar
grade) and shaken at intervals. It was allowed to stand for 3 days during which
time it was shaken periodically. The final extract was filtered using No 1 Whatman
filter paper. The crude
extract was regarded as 100% concentration and thereafter diluted serially into
20mls, 15mls,10mls, 5mls and 1ml using acetone to obtain 100%,75%, 50%, 25% and
5% of Dennetia tripetala,
respectively. Deltamethrin (synthetic pyrethroid )12.5 EC equivalent of
15.5g/l of active ingredient was used for the experiment. The serial dilutions
of the synthetic pyrethroid were prepared to include 1ml, 0.5ml, 0.25ml, 0.1ml
and 0.01ml using Acetone as solvent giving 5%, 2.5%, 1.25%, 0.5% and 0.05% of Deltamethrin
active ingredient respectively The maize grains
(Bende white) used for the experiment were sorted to remove damaged and broken
ones. The sample was sterilized in the refrigerator at 18 degrees Celsuis for 3 days to kill off any hidden infestations.
Thereafter it was allowed to condition at ambient laboratory conditions. Twenty
grams weight of the grains were placed in each of the transparent plastic cups
and each treated with 2mls of 100%, 75%, 50%, 25% and 5% of D. tripetala extract, respectively using a disposable
syringe. Ten adults of S. zeamais of mixed
sexes were introduced into each of the cups. The contents were covered with
muslin cloth and held in place with rubber bands. The control treatments had no
D. tripetala extract added and each treatment
was repeated 4 times. The insect mortality was recorded from12hours of
treatment and up to 72 hours. Insects were assumed dead on failure to respond
to gentle probing with a blunt dissecting needle. The same procedure was
adopted with 5%, 2.5%, 1.25%, 0.5% and 0.05% of Deltamethrin treatments. The
layout plan was CRD with four repetitions displayed on the laboratory work
bench. After 5 weeks
of infestation, samples of 20 maize grains were drawn from each replicate
sample and number of damaged grains were counted and recorded. The sample was
returned to the container and shaken, the process was repeated 2 more times and
the mean values were recorded. Data obtained
were analyzed using SPSS version 13 package. 3. RESULTSTable 1: Damaged
Grains
The LSD value
showed that there were significant differences (p<0.05) in damaged grains
between the maize treated with Dennetia tripetala and the ones treated with Deltamethrin. The
grains treated with Deltamethrin showed no damage. The LSD also indicated that
there was a significant difference (p<0.05) in the control
and 1ml, but no significant differences between 10mls, 5mls, 15mls and 20mls. Table 2: Progeny Production
The LSD value
indicated that there were significant differences (p<0.05) in progeny
production between the maize treated with Dennetia
tripetala and the ones treated with Deltamethrin.
There was no significant difference (p>0.05) among the different
concentrations of Deltamethrin with respect to progeny production. There was no
significant difference (p>0.05) between 10mls, 5mls and 15mls of Dennetia tripetala with
respect to progeny production. There were significant differences (p<0.05) between
1ml, 20mls and the treatments Table 3: Mortality Assesment
At 12hours,
the LSD value showed that there was no significant difference (p>0.05)
between 1ml, 5ml, 10mls, 15mls of D. tripetala and
0.01ml, 0.1ml of Deltamethrin. There was no significant difference (p>.05) between
0.01ml and 0.1ml. There was no significant difference (p>0.05) between
0.25ml and 0.5ml. 0.25ml and 0.5ml differed significantly from 0.1ml and 0.01ml
with the former having a higher level of mortality. There was also a
significant difference (p<0.05) at 1ml which presented the highest level of
mortality. The control had no mortality. There was no significant difference (p>0.05)
between 10mls, 15mls, 5mls and 1ml. There was a significant difference (p<0.05)
at 20mls and control At 24hrs, the
LSD value showedthat there was no significant
difference (p>.05) between 20mls of D. tripetala
0.01ml of Deltamethrin. There was no significant difference (p>.05)
between 1ml, 0.05ml, 0.25 and 0.1ml. There was a significant difference (p<0.05)
at 0.01ml and it presented a lower level of mortality. Similarly, there was no
significant difference (p>.05) between 1ml, 5ml, 10ml and 15mls. However,
there were significant differences (p<0.05) at 20mls and control. At 48hrs, the
LSD value showed that there was a significant difference (p<0.05) between Deltamethrin
and Dennetia tripetala.
There was no significant difference (p >0.05) between all the different
concentrations of Deltamethrin. There was no significant difference (p>0.05)
between 20mls, 15mls and 10mls with respect to mortality at 48hrs. There was no
significant difference (p>0.05ml) at 1ml and 5mls but they (p<0.05)
differed from 20mls, 15mls and 10mls. There was a significant difference (p<0.05)
between the control and all the treatment concentration At 72hrs, the
LSD value indicated that there was a significant difference (p<0.05) between
Deltamethrin and Dennetia tripetala. There was no further mortality in Deltamethrin,
all the insects were dead after 3 days of treatment. There was no significant
difference (p>0.05) between 20mls, 15mls and 10mls. There was no significant
difference (p>.05) between 1ml and 5mls but they differed significantly from
20mls, 15mls and 10mls with a lower level of mortality. There were significant
differences (p<0.05) between the control and all the treatment
concentration. 4. DISCUSSIONIn Table 1, no
damaged grain was recorded in Deltamethrin irrespective of the treatment level.
In Dennetia tripetala
damaged grains were found to be decreasing with increasing concentration. The
results of the present studies were in agreement with those of Udo (2015) where
the number of damaged grains decreased with an increasing concentration of Dennetia tripetala. In Table, 2 progeny
was found to be decreasing with increasing concentration In D. tripetala
treatment. The findings of the present studies similarly agreed with
the result of Udo (2015) where progeny decreased with increasing concentration
of Dennetia tripetala The same
level of mortality was observed after 48hrs irrespective of the treatment
levels as shown in Table 3. The present studies also agrees
with the result of Rajanish and Rohit (2014) where Deltamethrin
was effectively used in the control of S.
oryzae in wheat. The result was also similar to
those of Frank (1994), where Deltamethrin was effectively used in the control
of R. dominica Mortality was
found to increase with increasing concentration of D. tripetala .10mls, 15mls and 20mls gave
the same level of mortality from 48 hours. The observations of the present studies
further strengthen the results of Udo (2015) where mortality increased with
increasing concentration of Dennetia tripetala. The present findings agree with the result
of Olayinka (2014), where the mortality of Dermestes marculatus increased with increased
concentration of Dennetia tripetala. 5. CONCLUSION AND RECOMMENDATIONSince Deltamethrin
was able to kill the insects within 3 days irrespective of the concentration. It
could be suggested that it should be used at very low concentration in other to
minimize cost and its residual effect. D. tripetala
was able to control
the insects moderately at 20mls. Therefore, for effective control of the
pest.it could be applied at higher dose with repeated application. Unlike Deltamethrin,
the plant product will take longer time to give100% mortality while it does not
have a residual products and not toxic to human being. SOURCES OF FUNDINGNone. CONFLICT OF INTERESTNone. ACKNOWLEDGMENTNone. REFERENCES[1] Akinkurolere, R.O. Assessment of the insecticidal properties of Anhomanes difformis (P.Beauv) Powder on five beetles of stored produce. J. Entomol. 4(1): 2007, 51-55. [2] Frank, H.A. Efficacy of unsynergized deltamethrin and deltamethrin + chlorpyrifos-methyl combinations as protectants of stored wheat and stored corn from USA. Journal of stored research. 30(1): 1994, 87-94. [3] Nwana, I.E. A survey of storage coleoptiles which attack dry cocoyam chips in Nigeria. J. Stored Prod Res. 29(1): 1993, 95-98 [4] Ogungbite, O.C and Oyeniyi, E. New Bouldia laevis (Seem) as an Entomocide against Sitophilus zeamais infesting maize grain. Jordan. J. Biol. Sci. 7(1): 2014, 49-55. [5] Olayinka-Olagungu, J.O. Effects of two eco-friendly insecticides (Dennetia tripetala and Piper guineense) against Dermestes maculatus on smoked dried Clarias gariepinus (Pisces: Claridae). IOSR Journal of Environmental Science, Toxicology and Food Technology. 8(7) :2014, 37-43 [6] Rajanish, C.M and Rohit, K.P. Efficacy of different insecticides against S. oryzae Linn. In stored wheat seed. J. Biopest. 7(1): 2014, 18-21. [7] Udo, I.O. Laboratory evaluation of pepper fruit (Dennetia tripetala) against maize weevil (S. zeamais) on stored maize grains. Swift Journal of Agricultural Research. 69: 2015, 067-069.
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