Comparative Analysis Of Insecticidal Efficacy Of Leaf Extracts Biology Essay


Aqueous extract of plant materials from neem (Azadirachta indica) and "datura" (Datura alba) will be tested to check the damaging effect of Trogoderma grananrium Everts on stored wheat. The experiment will be carried out at Entomological laboratory, College of Agriculture D.G.Khan. Water extracts of neem and datura will be tested at six different concentrations i.e., 0, 10, 20, 40, 80 and 100 percent. Experiment will be laid out in Completely Randomized Design (CRD) having three replications. Data regarding different parameters will be collected according to standard procedures and analyzed statistically by using MSTATC, a statistical software program and treatment means will be compared by applying Least Significant Difference (LSD) test at 5% probability level. The results will be interpreted for the estimation of optimum treatment to minimize the damaging effect of Trogoderma granarium in wheat stored grains.


Wheat is the staple food for people of Pakistan and is grown on more than 9 million hectares. It contributed 14.4 percent to value added in agriculture and 3.1 percent to GDP during 2009-2010. Wheat was grown on 9.045 million hectares with the production of 25 million tones (Govt. of Pakistan, 2010). After harvest wheat is procured by public and private agencies for storage and sale. Most of the wheat grain is retained by the farmers for their domestic consumption and also used as seed purpose.

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Major biotic factors influencing wheat losses during storage are insects, moulds, birds and rats (Baloch et al.1994). Among them the insect pests cause serious losses during storage. Gentile and Trematerra (2004) reported that twenty types of insect pests are responsible to infest stored wheat while Chaudhry and Mahla (2001) observed 10 insect species of wheat in storage such as lesser grain borer, (Rhyzopertha dominicia (F). Khapra beetle, (Trogoderma granarium Everts), granary weevil, (Sitophilus granarius L.), Angoumois grain moth, (Sitotroga cerealella (Olivier) and red flour beetle, (Tribolium castaneum (Herbst) are very important (Khattak et al., 2000; Toews et al. 2000; Ebeling, 2002; Atwal, and Dhaliwal, 2005; Shafique et al., 2006). It is estimated that 5-10% of world's grain production is lost due to damage of insects. The losses may reach up to 50% in tropical countries where summer is hot and humid and storage facilities are improper and inadequate (Adams, 1998; Ahmad and Ahmad, 2002). Trogoderma granarium (Everts) is one of the most serious stored grain pest. Substantial loss of vitamins, thiamine, riboflavin and niacin at 25% and above in grain infestation by this insect pest (Jood and Kapoor 1994). Severe infestation may cause unfavourable changes in chemical composition. Larvae typically attack the embryo point or a weak place in the pericarp of grain or seed, but will attack other parts during heavy infestations. Young larvae feed on damaged seed, while older larvae are able to feed on whole grains. Severe infestation by Khapra beetle makes grain unpalatable and unmarketable due to depletion of specific nutrients (Jood et al., 1996).

Use of insecticides/fumigants to control storage insect pests give harmful residues and leads to insect resistance. In Pakistan, Trogoderma granarium has been observed to become resistant to phosphine due to substandard techniques of fumigantion (Irshad and Iqbal, 1994). Sharma and Kalra (1998) also reported resistance to phosphine in different developmental stages of Trogoderma granarium. Alam et al. (1999) recorded a high level resistance in Trogoderma granarium strains collected from Punjab and Sindh. To avoid this resistance and for safer environment the use of natural products is gaining the interest of many researchers (Xie et al., 1995; Das et al 2006). For safe and natural control of insect pests of stored products, neem (Azadirachta indica ) oil has been used successfully by several scientists and found its significant antifeedant potential (Seck, 1994). Keeping in view the utilization of the insecticidal properties of Azadirachta indica and Datura alba the present study will be conducted with the following objectives.

To evaluate the losses caused by Trogoderma granarium in undamaged stored grains of wheat.

To compare the insecticidal efficacy of Azadirachta indica and Datura alba against Trogoderma granarium in undamaged stored grains of wheat.

To find out the suitable concentration among the tested concentration of Azadirachta indica and Datura alba leaf water extract against Trogoderma granarium.


Pal et al., (1996) tested the insecticidal properties of alcoholic extracts of the leaves of "chandni" (Tabernaemontana coronaria), curry (Murraya paniculata), asriple (Lantana camara), eucalyptus (Eucalyptus sp.), neem (Azadirachta indica), rhizomes of sweet flag (Acorus calamus) as well as seeds of "imli" (Tamarindus indica) and neem seed oil and compared with the commonly used organophosphate insecticides, i.e., Malathion 50EC and Chlorphyrifos-methyl 50EC, for their comparative toxicity against the full-grown larvae of Trogoderma granarium. Their relative toxicity, based on LC50 in descending order was; Malathion Chlorpyrifos-methyl A. indica oil A. calamus coronaria T. indica A. indica leaves L. camara M. paniculata Eucalyptus sp.

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Sharma (1999) reported that neem seed kernel powder used at 4% and neem leaf powder used at 5% protected the maize, for 5 months, against Rhizopertha dominica and Trogoderma granarium. Neem oil (1%) was found to be toxic to Tribolium castaneum and Sitophilus oryzae, while the neem oil (2%) effectively reduced the emergence of F1 and F2 progeny of all the pests and completely protected maize upto 9 months.

Yalamanchilli et al. (2000) reported that oral administration of A.calamus extract affected larval and adult forms of T.castaneum. Periodical observation over 125 days revealed a definite phago-deterrent activity of the extract.

Jilani et al. (2003) investigated the growth inhibition effect of neem seed oil, obtained from different localities of Pakistan, upon red flour beetle (Tribolium castaneum), in the laboratory conditions and established significant reduction in progeny at 250 ppm concentration in case of all the samples.

Khan and Marwat (2003) evaluated the powders made from leaves, seeds and bark of Azadirachta indica and Nerium oleander for their detterent effects against Rhizopertha indica and got it's repellency upto 96% from neem leaves and seeds.

Nazli et al. (2003) reported the neem seed oil, in the laboratory studies, as an insect repellent against red flour beetle. Neem seeds were collected from different localities of Pakistan. They observed repellence by the beetles up to 52.25% in response to the neem seed oil obtained from Hyderabad.

Dwivedi and Shekhawat (2004) conducted an experiment to observe the repellent action against Khapra beetle. Olfactometre was used to confirm repellent property in all the plant species.

Hassan et al. (2006) reported that overall percent mortality of Trogoderma granarium at 1.5% concentration of Holxylon recurum extract at 168 hours exposure time was 23 % as against 39 % with deltamethrin at the same dose.

Das et al. (2006) evaluated the efficacy of different concentrations of the commercial neem-based insecticide, Nimbicidine® against the eggs of the red flour beetle, (Tribolium castaneum Herbst). The insecticide significantly inhibited the hatching, pupation and adult emergence of the beetle. The latent effects of Nimbicidine® on the next generation progenies were expressed by significant reductions in the growth of larvae, pupation and adult emergence coupled with lengthened developmental period, but the sex ratio was unaffected.

Ahmad et al. (2007) reported that azadirachtin, the active ingredient of neem extract, was tested at two produced formulations (Neem-Azal T/S and Neemix) against mature and immature stages of bean aphid (Aphis fabae Scop.).Three tested concentrations of azadirachtin (1.0, 2.0 and 2.5 μl/100ml water) of both products were used. Adult and nymphs toxicity were evaluated using two different application techniques (contact and systemic). Effect of neem products on reproduction of adult aphids, developmental rate of born nymphs and maturation percentage were studied. Both products caused marked effects on adult aphid when used as systemic insecticides, while no toxicity was observed when used as contact poisons. Toxicity of the tested products to nymphs increased according to concentration and exposure time and the efficiency of Neemix was clearly observed at all compared parameters. Systemic technique was more effective than the contact one at both products. Phytotoxicity was clearly observed at higher concentrations than 2.0μl/ 100ml water of Neemix and exposure time longer than two days at systemic experiment, while Neem-Azal T/S gave no phytotoxicity at all.

Parugrug and Roxas (2008) reported that all test materials exhibited repellency action against maize weevil. Powdered leaves of neem and lantana were noted to be highly repellent while powdered leaves of lemon grass,basil and African marigold were observed to be moderately repellent against maize weevil within 96 hours of exposure.

Kudachi and Balikai (2009) evaluated that A.calamus rhizomes @ 1% was found to be significantly superior in protecting sorghum grains Rhizopertha dominica up to 180 days after treatment followed by A.squamosa seed powder @ 5%,malathion 5% dust and A.indica seed powder @ 5% with minimum seed damage, higher germination percentage, minimum weight loss and maximum adult mortality.

Egwurube et al. (2010) reported that neem seed powder (NSP) was next to Actellic dust in efficacy followed by the neem leaf powder (NLP); all significantly better than the untreated control in causing greater larval mortality, reduced progeny emergence and seed damage with no harm to seed viability. Actellic dust at 5 and 10% w/w was more effective than the plant materials as 100% mortality was achieved within 24 h post-treatment with no seed damaged. NSP treatment gave 100% mortality only at 10% w/w level with about 6.5% and 6.7% seed damage and progeny emergence respectively, while NLP was the least efficacious giving 50% mortality at 10% w/w, 28% seed damage and 33% progeny emergence in 24 h but better than the untreated control in all the parameters evaluated.

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Satti et al. (2010) determined that neem seeds stored at 2, 3 and 4 years were better than the seeds stored at 1 or 5 years, in controlling the studied pest. The newest seeds (1year) seemed to exert more repellent effect than older seeds.

Different scientists have also worked on Trogoderma granarium by using extracts of different plants and some extracts are very toxic and achieve maximum mortality. But I have selected the aqeous extracts of neem and datura and I will describe their effects on mortality of Trogoderma granarium and extracts of these plants have too much toxicity against Trogoderma granarium.


The proposed research will be conducted in the Entomological Lab. College of Agriculture, Dera Ghazi Khan by using Completely Randomized Design (CRD) with three replications. The experiment will be conducted for a period of 4 months.

Rearing of insect

Adult insects will be collected from godowns located at different areas in D.G. Khan and will be reared in glass jars covered with muslin cloth. Rearing will be done in laboratory on undamaged stored grains of local wheat variety Sahar 2006. Temperature 27± 1°C and 55±5% RH will be maintained in an incubator.

Preparation and application of extracts

Mature plant leaves of Azadirachta indica and Datura alba will be collected from different villages of D.G. Khan, dried for few days under shade (at a temperature 35°C ± 2) and then chopped into 2 cm pieces with electric fodder cutter. Chopped leaves will be soaked in distilled water in ratio of 1:10 (w/v) for 24 hours (Iqbal, 2007).The extract will be filtered with the help of sieves of 10 mesh gradually and boiled at 100°C to evaporate water to decrease volume up to 20 times. The grains will be treated with concentration i.e. 10%, 20%, 40%, 80% and 100%. Let the jars open for few hours for allowing the moisture to evaporate. After that insects will be released in jars @ 16 insects/100 grams wheat grains (Collins, 1998). Jars will be covered with muslin cloth.


i. Control (100 ml Distilled water)

ii. 10% (10 ml botanical extract + 90 ml distilled water)

iii. 20% (20 ml botanical extract + 80 ml distilled water)

iv. 40% (40 ml botanical extract + 60 ml distilled water)

v. 80% (80 ml botanical extract + 20 ml distilled water)

vi. 100% ( 100 ml botanical extract)

Wheat grains having weight 250 gm of variety Sahar 2006 will be used for each treatment and total volume concentrations required for pasting 250 g wheat grains will be 100 ml.


Following parameters will be recorded during the course of studies as per standard procedures.

Loss in grain weight (g)

Loss in grain weight will be measured by calculating the difference between grain weight before releasing the insects and after trial completion in all treatments and then percentage of loss in grains weight will be measured and will also be compared with control samples.

Mortality (%)

Percent mortality = no. of insects alive in test / no. of insects alive in control Ã- 100

Insect count

Insect count will be done after trial completion after releasing a specified number of insects in treated grains along with control. The effect of Azadirachta indica and Datura alba will be observed at their different concentration level of 10%, 20%, 40%, 80%, and 100% of leaf extracts. Mortality of Trogoderma granarium will be measured after releasing 40 adults in each treated jar of wheat grains at different neem and datura concentrations. After trial completion each jar will be observed and then % age of number of insects will be measured and will also be compared with control samples.

Repellency studies

Repellency studies will be carried out by using filter paper strip method. Filter paper (Whatman No. 1) will be cut into strips of 8 Ã- 10 cm dimensions. Half filter paper strips will be treated with 1 ml of extract and will be allowed to air dry for 10 minutes. Each treated half strip will be then attached lengthwise, edge to edge to a control half strip with adhesive tape and will be placed in a petri dish. Twenty adult insects will be released in the middle of each filter paper circle in petri dish. Insect that settled on each of the filter paper strip will be counted after 1 hour and then at hourly intervals for 5 hours.