Storage Stable OW Emulsions of Karanj.pdf

Chapter5‐StableO/WEmulsionsofKaranj,CastorandNeemOilforPesticideApplications.

StudiesinMixedSurfactantSystemsandVegetableOilEmulsions 135

Chapter 5 -

Storage Stable O/W Emulsions of Karanj

(Pongamia glabra), Castor (Ricinus communis

L.) and Neem Oil (Azadirachita indica A. Juss)

for Pesticide Applications



5.1 Introduction

Synthetic agrochemicals are responsible for ecological imbalance, food chain

disruption, stream water contamination resulting into human and animal toxicity and

traces in agricultural products even in breast milk. These agrochemicals also have pre-

application hazards such as process pollution, occupational hazard and handling exposure.

The exaggerated perception of such hazards has forced researchers to find a

comparatively safer alternative for these chemicals. Some of the easily available non-

edible vegetable oils are having major anti insect actives in addition to their fatty acid

composition.

Karanj based products are found to be effective against insect pests of stored

grains, field and plantation crops, and household commodities.315 More than nineteen

biologically active components have been identified from karanj plant. Oil, organic leaf

extract, methanolic and aqueous seed extract, of karanj have shown potential to act as

oviposition deterrents, antifeedants, antibacterial, antifungal, mosquito repellent and

larvicidal against a wide range of insects.316 - 321 Karanj oil (Pongamia glabra) contains the

non-glyceride toxins Karanjin and Pongamol.322, 323 The bioefficacy of Karanj, and Neem

oil against Mustard aphid, Lipaphis erysimi (Kaltenbach) under different cropping

systems were shown significant reduction in the mustard aphid population. Effects of

karanj seed extracts on growth and development of Plutella xylostella L. (Lep.,

Yponomeutidae) and on oviposition and egg hatching of Plutella xylostella (Lepidoptera:

Yponomeutidae) have proved their potential as a promising agrochemical.324 - 326

The ricin and ricinine are active ingredients of Ricinus communis that acts against

S. frugiperda. Castor seed extract keeps more insecticidal and insectistatic potential than

the leaf extract.327 It resulted in effective seed protection from Z. subfasciatus infestations

comparable to the control of malathion with least seed damage, weight loss and without

any adverse effect on germination capability of the seeds.328 Castor and Hazelnut oil have

shown insecticidal activity against Callosobruchus maculatus (F.) (Coleoptera:

Bruchidae),329 Musca domestica330 and termites.331

A tetranortriterpenoid Azadirachtin (C35H44O16) present in Neem oil is the most

potent, natural insect feeding deterrent as well as insect growth regulator to which over

200 species of insects are found to be susceptible.332, 333 The activity of Neem seed oil on

various pests is explored viz. Lutzomyia longipalpis (Diptera: Psychodidae),334

Rhipicephalus (Boophilus) microplus,335 whorl larva, stem-borer and panicle insect pests

of sorghum,336 red flour beetle, Tribolium castaneum (Herbst) (Coleoptera:



Tenebrionidae), lphitobius diaperinus (Coleoptera: Tenebrionidae).337 In addition to

synergistic fungicidal activity Neem oil is responsible for repellency against Phlebotomus

orientalis, P. bergeroti (Diptera: Psychodidae),338 large pine weevil, Hylobius abietis L.

(Coleóptera, Curculionidae).339, 340 The in vitro toxicity of neem seed oil was proved

against the larvae of a one-host tick, Boophilus decoloratus (family: Ixodidae or hard

tick,commonly known as blue tick) and for ovicidal activity on the eggs of bhendi.341

Tropical environment is suitable for Karanj, Castor and Neem tree. They are

grown in a wide area stretching from Australia, India to south and North American

territory. These oils are readily available in market at reasonable cost. Profitable oil

isolation methods from well dried seeds include processes like cold dry pressing, steam

distillation and solvent extraction technique. Formulation of crude vegetable oil is

advantageous over the isolation and formulation of actives as it includes other potentially

biotoxins present in seed and possesses excellent storage stability.342, 343

Vegetable oils, like all other botanical resources, will considerably vary with

respect to their bioactive content depending upon the variation in tropical conditions and

efficiency of oil extraction technique. The agrochemical and medicinal importance of

Karanj, Castor and Neem oil is proved by the series of above discussed work. However,

direct application of vegetable oil has drawback like high viscosity, less spreadability,

cost of oil, probable overdose resulting into unconsumed residues in soil and aquatic

system. This demands a suitable economically feasible formulation technique for their

widespread agrochemical applications. The present study was focused on developing the

stable O/W emulsions with varying oil content while keeping emulsifier content to

minimum level. Emulsifying agents are well known to play an important role in the

stability of emulsion and proper selection of the emulsifying agents gives the synergistic

effect.344 The blend of nonionic surfactants viz. NP-13 (HLB No. 15) and Span-80 (HLB

No. 4.5) was used for emulsion formation. The emulsion stability studies were carried out

at 30°C ± 0.5°C for 24 hrs and the stable emulsions were further tested for their

rheological and insecticidal properties.



5.2 Materials and Methods

5.2.1 Materials

Karanj, Castor and Neem oil were procured from M/s. Ashwin Pharma Ltd.

Mumbai, India. NP13 (Nonyl Phenol Ethoxylate 13 Moles) and Span80 (Sorbitan

Monooleate) were procured from M/s. SD Fine Chemicals, Mumbai, India. All other

chemicals were of analytical grade. Deionized water was used for experimental work.

Mosquito larves (Third stage/early fourth stage) were supplied by “Dr. Balasaheb Sawant

Konkan Krishi Vidyapeeth.” (Dr. Balasaheb Sawant Konkan Agriculatural University,

Dapoli, India). All other chemicals were obtained from M/s. S. D. Fine Chemicals Ltd.

Mumbai, India and used without further purification.

5.2.2 Methods

5.2.2.1 Preparation of Emulsion

Emulsions were prepared under the influence of external agitation with the help of

homogenizer. In each case calculated quantity of emulsifier blend was dissolved in oil

phase which was then added to the aqueous phase under the influence of external

agitation with the help of electrically driven motor (2000 RPM- Remi Motors Ltd. India).

The prepared emulsions were then observed for macroscopic stability for 24 h at 30°C ±

0.5°C. The emulsion instability was expressed in terms of “creaming” while the white

milky layer is treated as a stable emulsion.

5.2.2.2 Effect of Various Parameters

Initially the emulsifier content was kept constant at 3% (w/w) level and oil content

was varied from 1% (w/w) to 15% (w/w). However, the emulsions were found to be

unstable. This procedure was repeated by varying the emulsifier content. Emulsifier blend

of various HLB numbers were prepared by properly adjusting the percentage of

individual surfactant as shown in Table 5.1.



Table 5.1 - Preparation of emulsifier blends with varying HLB number. NP-13 (wt. %) Span-80 (wt. %) HLB number of emulsifier blend

0.00 100.00 4.5 4.60 95.40 5 14.28 85.70 6 23.80 76.20 7 33.30 66.70 8 42.86 57.10 9 52.40 47.60 10 61.90 38.10 11 71.40 28.60 12 81.00 19.00 13 90.50 9.50 14 100.00 0.00 15

5.2.2.3 Rheological Characterization

Rheological properties of the final emulsion intended to be used as a sprayable

product decides the physical stability, ease of spraying, spreadability and its overall

performance.345 In case of O/W emulsions viscosity is typically governed by the amount

of internal oil phase. “Haake VT500 Viscometer (Germany)” operated by “Thermo

Rheowin 2.97 software” equipped with DC-5 cooling system was used for rheological

characterization. The 35 g of each emulsion sample is subjected to a shear programme

from 6.45S-1 to 645S-1 with 1 minute time interval. Each rheological measurement was

performed in three replications and average ± S.D. values were plotted. Rheological

parameters like consistency index (K), flow index (n) were calculated by applying

“Power law” model.346, 347

5.2.2.4 Spreadability on plant leaves and average globule size

The emulsions were checked for there spreadabilty on horizontal coconut leaves.

A circle of 1 cm diameter was drawn on leaf and a drop of emulsion was placed at the

centre of the circle. The average time required for emulsion drop to touch the opposite

ends of the circle is noted for three independent replications. The average globule size of

emulsion is determined in five replications using COULTER LS230 instrument.

5.2.2.5 Larvicidal Activity

The most efficient and simpler way to control mosquito population is

larviciding.348 In the present paper the larvicidal activity of developed formulations were



tested using twenty five larve of each mosquito species at 25-28°C with a photo period of

12 hr L: 12 hr D.349 Initially a series of trial experiment (non replicated) were conducted

with different test formulations to optimize the dose with a geometric factor of 2.0 giving

5–95% mortality. Test formulations were composed of single as well as equal volume

mixtures of two and more emulsions. Single oil emulsion concentrations used were 0.01,

0.02, 0.04, 0.08, 0.16, 0.32, 0.64, 1.28, 2.56 and 5.12% whereas for an equal volume

mixture of two and three oil emulsions the lower limit of the test formulation percentage

were started from 0.0025 and 0.001 respectively. Each measurement is performed in four

replications. After 24 hr, the number of dead larves was counted and the data was

subjected to probit analysis350 using NCSS 2007 statistical package. Increase in mosquito

larvicidal efficacy is expressed in terms of fold increase and calculated using the formula:

Fold increase = LC50 or LC90 or LC95 of individual emulsion treatment / LC50 or

LC90 or LC95 of combination emulsion treatment.



5.3 Results and Discussion

5.3.1 Optimum Emulsion Parameters

A series of stable emulsion products were developed by trial and error method

considering the ease of emulsion formation and emulsion stability for 24 hrs at 30 ± 0.5°C

are depicted in Table 5.2. Practically the apparent viscosity, specific gravity of these oils

was matching and the peak emulsification performance is achieved by matching HLB

numbers. The equipment used for emulsification such as beaker dimensions, speed of

agitation and agitation blade geometry were found to be ideal in case of emulsions with

10% oil concentration as the same quantity of emulsifier i.e. 5% was required. The

increase in emulsion particle size is obtained with increasing internal oil phase. The

increase in oil content has increased viscosity of the emulsion there by reducing

spreadability of emulsion droplet.

Table 5.2 - Optimum emulsion parameters.

Formula

Oil Composition (wt %) NP 13:

Span 80

Phase mass ratio

(ϕm)

Avg. Spred ability

(S)

Avg. globule size (µm)

Oil Emulsifier blend

Water

1 Karanj 5 2.5 92.5 3.3:6.7 0.0540 3 0.972 2 10 5.0 85 0.1176 7 1.710 3 15 8.3 76.7 0.1955 9 2.073 4 20 11.2 68.8 0.2906 12 4.085 5 25 12.5 62.5 0.4000 19 6.097 6 30 13.7 56.3 0.5328 27 9.452 7 35 15.2 49.8 0.7028 38 12.983 8 40 17.3 42.7 0.9367 42 17.35 9 Castor 5 2.4 92.6 9.05:0.9

5 0.0539 2 0.345

10 10 5.0 85.0 0.1176 5 0.723 11 15 7.8 77.2 0.1943 9 1.570 12 20 10.3 69.7 0.2869 14 2.654 13 25 11.9 63.1 0.3961 20 3.871 14 30 13.5 56.5 0.5309 24 6.286 15 35 14.6 50.4 0.6944 26 8.592 16 40 16.1 43.9 0.9111 34 13.233 17 Neem 5 3.1 91.8 8.1:1.9 0.0544 2 1.004 18 10 5.0 85.0 0.1176 4 2.320 19 15 7.9 77.1 0.1945 7 3.002 20 20 10.1 69.9 0.2861 12 4.975 21 25 12 63 0.3968 16 6.087 22 30 13.5 56.5 0.5309 23 9.073 23 35 14.3 50.7 0.6903 30 11.238 24 40 15.9 44.1 0.9070 37 15.985



5.3.2 Effect of Oil Content on Stability

At a given emulsifier percentage (3% w/w) as the oil percentage increased, the

stability of emulsion increased up to a maximum value at 10% of oil content and further

increase in the oil content was resulted into the destabilization of emulsion. Emulsion

instability at lower oil content may be due to the difference in the gravitational forces

whereas the surfactant deficiency unable to form the tight monolayer around dispersed oil

droplet caused instability at higher oil content. This ultimately resulted into successive

collisions of oil droplets leading to coalescence and destabilization of emulsion. Figure

5.1 shows the effect of oil content on stability of emulsion.

Figure 5.1 - Effect of oil content on stability of emulsion at 3% (w/w) emulsifier

content.



5.3.3 Effect of Emulsifier Content on Stability

Polyethoxylated nonionics are soluble in water due to hydrogen bonding of water

molecule to the oxygen atom of polyoxyethylene chain. The surfactant molecules from oil

phase and water phase get associated in a particular way at the O/W interface. Sufficient

emulsifier concentration is necessary to produce the tightly packed monolayer of

surfactant molecules at the interface which acts as a mechanical barrier to flocculation

and coalescence of oil droplets thereby stabilizing the emulsion. The effect of emulsifier

content on the stability of emulsion is shown in Figure 5.2

Figure 5.2 - Effect of emulsifier content on stability of emulsion at 10% (w/w) oil

content.

At emulsifier concentration of 5% the maximum stable emulsion was obtained.

The emulsifier concentration lower than this was unable to prevent the flocculation and

coalescence of oil droplets and consequently destabilized the emulsion. The emulsifier

concentration above 5% also destabilized the emulsion due to the temporary emulsifier

saturation in inter droplet region.



5.3.4 Effect of HLB Number of Surfactant Blend on Stability

Maximum stability for karanj, castor and neem oil emulsions is obtained at HLB

of surfactant blend 8, 14 and 13 respectively. The HLB numbers of surfactant blend fairly

match with those of oils, which is one of the conditions to get the stable emulsion. Figure

5.3 shows the effect of HLB number of surfactant blend on the stability of emulsion.

Figure 5.3 - Effect of HLB of surfactant blend on stability of emulsion at 10% (w/w)

oil content and 5 % (w/w) emulsifier content.



5.3.5 Effect of Hardness of Water on Stability

In agricultural applications the hardness of water is the matter of great concern as

it varies with the location. Figure 5.4 shows the effect of hardness of water on stability of

emulsion. The maximum limit of hardness of water was found to be 342 ppm, above

which the emulsions were gradually destabilized. Neem oil emulsion showed maximum

tolerance for hard water followed by karanj oil emulsion and castor oil emulsion showed

the least tolerance.

Figure 5.4 - Effect of hardness of water on stability of emulsion at 10% (w/w) oil

content and 5% (w/w) emulsifier content.



5.3.6 Rheological Characterization

All formulated emulsions showed a pseudoplastic flow behavior i.e. shear

thinning nature which is the characteristics of a good sprayable O/W emulsion product.

Viscosity measurement of karanj oil emulsion is shown in Figure 5.5.

Figure 5.5 - Viscosity measurement of formulated karanj oil emulsions.

The oil content is the main viscosity determining parameter being viscous and

variable. In case of all emulsion varying oil content a rapid decrease in viscosity at the

initial shear rates is obtained which further decreased slowly at higher shear rates which

an indication of increased spray efficiency. Rheogram of karanj oil emulsion is shown in

Figure 5.6. Rheograms of castor and Neem oil emulsion are found to be identical in graph

nature and flow behavior hence only rheological parameters are given for them.



Figure 5.6 - Rheogram of formulated emulsions.

Table 5.3 contains the values for “power law” model showing the empirical

consistency (k) and flow behavior indices (n). The correlation coefficient (r2) values

ranging from 0.989 to 0.998 suitably explains the experimental data. The increase in oil

percentage has resulted into increase in apparent viscosity thus statistical increase in

empirical consistency index which is the indication of viscosity.



Table 5.3 - Rheological parameters of stable emulsions.

Formula Consistency Index (k) Flow Index (n) Correlation coefficient (r2)

1 62 ± 3.4 0.34 ± 8.5 × 10-3 0.991 2 70 ± 8.1 0.35 ± 1.5 × 10-3 0.994 3 76 ± 1.5 0.46 ± 5.6 × 10-3 0.994 4 83 ± 12 0.46 ± 7.4 × 10-2 0.992 5 90 ± 5.3 0.34 ± 3.9 × 10-3 0.992 6 113 ± 16.2 0.34 ± 5.7 × 10-2 0.993 7 125 ± 10.5 0.47± 2.9 × 10-2 0.994 8 130 ± 2.5 0.46 ± 2.1 × 10-2 0.991 9 57 ± 6.0 0.34 ± 8.9 × 10-3 0.989 10 60 ± 8.5 0.34 ± 2.2 × 10-2 0.992 11 72 ± 7.1 0.47 ± 3.2 × 10-2 0.993 12 85 ± 12.0 0.46 ± 8.2 × 10-2 0.993 13 95 ± 10.4 0.34 ± 2.3 × 10-2 0.991 14 110 ± 22.3 0.34 ± 5.1 × 10-3 0.993 15 129 ± 19.0 0.48 ± 6.5 × 10-3 0.989 16 136 ± 23.3 0.47 ± 1.2 × 10-2 0.994 17 47 ± 3.2 0.44 ± 4.2 × 10-2 0.989 18 53 ± 5.5 0.37 ± 2.9 × 10-2 0.924 19 67 ± 6.1 0.46 ± 3.1 × 10-2 0.990 20 79 ± 7.2 0.39 ± 7.1 × 10-3 0.994 21 92 ± 10.2 0.42 ± 4.2 × 10-2 0.998 22 123 ± 15.6 0.45 ± 3.4 × 10-2 0.992 23 136 ± 20.2 0.34 ± 6.9 × 10-2 0.993 24 157 ± 23.5 0.34 ± 2.5 × 10-2 0.989

Values of flow index were consistently below unity which indicates a

pseudoplastic flow behavior. The consistency index increased with increase in oil content.

From the rheological data the formulated emulsions were found to have optimal viscosity,

pseudoplastic flow nature and good consistency.

5.3.7 Larvicidal Activity:

The results of the larvicidal activity are depicted in Table 5.4 to 5.7. From the

study, it was clearly observed that the combination of Karanj, Neem and Castor oil

emulsions were found to be more effective than their individual treatment against all the

mosquito larvae tested. The increase in efficacy of the combination Karanj, neem &

castor oil emulsion treatment (1:1:1) over individuals in all the mosquito larvae tested

was found to range from 8.4 to 9.5 fold for karanj oil, 5.5 – 16.0 fold for neem oil and

16.2 to 23.9 fold for castor oil emulsion in terms of LC50. Similar increaments were also



observed in case of LC90 and LC95 for a combination treatment of karanj, neem and castor

oil emulsion (1:1:1)

The overall order of larvicidal activity is found to be,

karanj, neem & castor (1:1:1)>karanj and neem (1:1) > Neem and castor (1:1)> Karanj

and neem (1:1)> karanj > Neem > castor

Hence, the oil formulations are economically and practically feasible method to

control mosquito larvae. From the present investigation, it is obvious that the performance

of combined application of neem and karanj oil emulsion was better against the mosquito

larvae than their individual application. Though the individuals are good against mosquito

larvae, the synergistic effect is well exhibited in this experiment. Use of the above

products in alternation with the chemical insecticides may help in causing delay in the

development of resistance in variety of pests.



Table 5.4 - Larval mortality data of karanj, neem and castor oil emulsions. Emulsion concentrations (%)

Corrected larval mortality at 24 hr (%)*

Culex quinquefasciatus

Aedes aegypti Anopheles stephensi

Karanj oil 0.01 5 (0.35) 6(1.91) 8(1.2) 0.02 14 (2.95) 13(2.58) 20(3.4) 0.04 36 (3.2) 29(1.63) 52(4.2) 0.08 42 (1.95) 37(3.65) 59(2.83) 0.16 63 (2.5) 68(3.27) 65(2.75) 0.32 74 (3.7) 78(2.52) 78(3.52) 0.64 84 (2.58) 86(2.58) 89(3.80) 1.28 91 (3.27) 92(1.23) 94(2.38) 2.56 100 100 100 Untreated control 0.00 0.00 0.00 Castor oil 0.01 0.00 0.00 0.00 0.02 4(0.48) 7(0.45) 2(0.85) 0.04 12(0.93) 14(1.03) 15(0.85) 0.08 32(1.28) 25(0.64) 27(1.16) 0.16 48(1.64) 47(0.82) 41(2.10) 0.32 65(2.83) 70(1.02) 59(3.64) 0.64 78(3.54) 81(1.85) 75(3.97) 1.28 86(3.73) 92(3.28) 93(4.86) 2.56 93(3.95) 100 98(4.07) 5.12 100 - 100 Untreated control 0.00 0.00 0.00 Neem oil 0.01 2(0.26) 0.00 0.00 0.02 19(0.83) 9(0.47) 7(0.38) 0.04 37(1.09) 17(0.67) 15(1.16) 0.08 59(1.59) 33(1.28) 28(1.24) 0.16 76(2.06) 69(1.83) 55(2.74) 0.32 92(2.68) 85(2.06) 79(2.93) 0.64 98(3.06) 91(2.72) 85(3.02) 1.28 100 100 93(3.9) 2.56 - - 100 Untreated control 0.00 0.00 0.00

*Mean of four replications; Values in parentheses are standard errors



Table 5.5 - Larval mortality data of combination of emulsions against different

mosquito species.

Emulsion (%) Corrected larval mortality at 24 hr (%)* Culex quinque. Aedes aegypti Anoph. steph. Karanj + castor + neem oil 0.001 9(2.43) 3(0.31) 5(0.28) 0.0025 18(2.93) 15(0.48) 19(0.3) 0.005 34(3.74) 32(0.83) 42(1.29) 0.01 44(3.83) 49(1.03) 58(2.03) 0.02 64(4.04) 67(1.28) 69(2.84) 0.04 76(4.32) 78(1.93) 78(2.93) 0.08 80(5.02) 91(2.37) 92(4.80) 0.16 96(5.08) 98(3.28) 100 0.32 100 100 - Untreated control 0.00 0.00 0.00 Karanj + castor oil 0.0025 1(0.04) 3(0.32) 7(0.05) 0.005 7(0.23) 10(1.63) 21(0.83) 0.01 24(0.48) 19(1.90) 33(0.73) 0.02 38(0.73) 35(2.63) 45(1.73) 0.04 49(0.83) 55(3.84) 59(1.83) 0.08 65(1.8) 67(4.83) 75(2.18) 0.16 79(2.93) 81(5.25) 87(3.67) 0.32 94(3.04) 98(5.05) 93(5.48) 0.64 100 100 100 Untreated control 0.00 0.00 0.00 Castor + neem oil 0.0025 6(1.28) 9(0.08) 3(0.012) 0.005 13(1.58) 21(0.82) 7(0.27) 0.01 25(2.04) 31(1.20) 14(0.59) 0.02 39(2.54) 52(1.73) 25(0.92) 0.04 55(3.19) 69(2.19) 58(1.03) 0.08 79(3.27) 82(3.28) 75(1.28) 0.16 92(4.03) 92(4.10) 89(2.86) 0.32 98(5.38) 100 100 0.64 100 - - Untreated control 0.00 0.00 0.00 Karanj + neem oil 0.0025 4(0.03) 9(1.03) 7(0.76) 0.005 19(0.37) 21(1.37) 21(1.13) 0.01 35(0.92) 42(2.04) 33(1.85) 0.02 45(1.29) 63(2.97) 45(2.18) 0.04 67(1.73) 74(3.28) 59(3.14) 0.08 79(2.95) 83(3.79) 75(3.82) 0.16 85(3.74) 92(4.02) 87(4.58) 0.32 93(4.70) 99(4.93) 93(5.32) 0.64 100 100 100 Untreated control 0.00 0.00 0.00

*Mean of four replications; Values in parentheses are standard errors



Table 5.6 -Data on LC50, LC90, LC95 of karanj, neem and castor oil emulsions

against mosquito larvae.

Emulsion Mosquito species LC50

(%)

LC90

(%)

LC95

(%)

Regression

equation r2

Karanj +

Castor +

Neem

Culex quinquefasciatus 0.011 0.106 0.203 Y=1.319X + 7.561 0.979

Aedes aegypti 0.011 0.064 0.107 Y=1.681X + 8.279 0.992

Anopheles stephensi 0.009 0.065 0.114 Y=1.581X + 8.078 0.978

Karanj +

Neem


Aedes aegypti 0.015 0.098 0.167 Y=1.604X + 7.845 0.983


Karanj +

Castor


Aedes aegypti 0.033 0.188 0.312 Y=1.691X + 7.504 0.975


Neem +

Castor


Aedes aegypti 0.018 0.134 0.236 Y=1.507X + 7.594 0.998


Karanj


Aedes aegypti 0.094 0.769 1.409 Y=1.408X + 6.440 0.967


Neem


Aedes aegypti 0.109 0.506 0.788 Y=1.927X + 6.849 0.979


Castor


Aedes aegypti 0.182 0.857 1.993 Y=1.588X + 6.174 0.994


LC50, LC90 and LC95are the concentration required to kill 50, 90 and 95% of the test

populations respectively,

LC50 / LC95 ± Fiducial limits with 95 % confidence,

Y = Probit mortality; X = Concentration



Table 5.7 - Increase in efficacy of karanj, neem and castor oil emulsion

combination over individuals against mosquito larvae.

Mosquito Species

Fold increase of combination Karanj + Neem + Castor oil emulsion (1:1:1)

Over karanj oil emulsion

Over Neem oil emulsion

Over castor oil emulsion

LC50 LC90 LC95 LC50 LC90 LC95 LC50 LC90 LC95 Culex quinq. 9.29 8.87 8.75 5.53 2.51 1.96 18.9 14.3 13.2 Aedes aegyp. 8.47 11.9 13.1 9.79 7.84 7.34 16.2 13.2 18.5 Anoph. steph 9.53 11.3 11.9 16.0 12.8 12.0 23.9 18.8 17.5 Karanj + Neem oil emulsion (1:1)

Over karanj oil emulsion Over Neem oil emulsion LC50 LC90 LC95 LC50 LC90 LC95

Culex quinq. 4.25 4.892 5.091 2.534 1.385 1.143 Aedes aegyp. 6.08 7.82 8.42 7.03 5.14 4.709 Anoph. steph 3.190 2.700 2.574 5.377 3.052 2.593 Karanj + castor oil emulsion (1:1)

Over karanj oil emulsion Over castor oil emulsion LC50 LC90 LC95 LC50 LC90 LC95

Culex quinq. 2.617 4.000 4.520 5.320 6.445 6.814 Aedes aegyp. 2.875 4.077 4.509 5.524 4.542 6.378 Anoph. steph 3.411 3.377 3.313 8.557 5.615 4.893 Neem + castor oil emulsion (1:1)

Over Neem oil emulsion Over castor oil emulsion LC50 LC90 LC95 LC50 LC90 LC95

Culex quinq. 2.544 1.896 11.48 8.689 10.78 11.48 Aedes aegyp. 5.804 3.772 3.336 9.654 6.385 8.437 Anoph. steph 4.283 4.516 4.587 6.375 6.644 6.724

5.3.8 House Fly Repellency

An UCR strain of Musca domestica is used in the repellency assay. A continuous

access to a mixture of skimmed milk powder / sugar (50:50) and water was given to flies.

A fly repellency chamber was made using a nylon-66 fibre net (having windows of ~2

mm diameter) and acrylic glue. The chamber dimensions were 20X20X10cm. The

multiple holes of the net maintained the air ventilation in the chamber. The chamber was

divided in four equal parts of dimension 10X10X10 cm. Four tightly woven cotton cloths

of 10X10cm were fixed at each divided floor part. Opposite corner cloths are used to

support test and placebo emulsion formulation. Test and placebo formulations (2mg/cm2)

were evenly distributed on the cotton cloth using a small pipette. The 50 flies (briefly

anaesthetized using CO2) were added to the chamber. Fly count was performed after the



interval of 1 hr and up to 3 days depending upon the fly positioning on the test and

placebo emulsion applied cotton cloth.

Fly count within the chamber showed that the flies were far away from the test

formulation applied cloth and were found to be very commonly distributed over the

untreated area of the chamber. 2 mg/cm2 concentration of oil emulsion showed a

promising fly repellency up to 72 hrs. The fly repellency potential of formulated oils were

found in the order of karanj > neem > castor. Table 5.8 shows the Musca domestica

repellency as a function of time.

Table 5.8 - Musca domestica repellency potential of formulated emulsions.

Emulsion

(Formula)

Musca domestica repellency % (after hrs)

2 4 8 12 24 48 72

Karanj (1) 100 100 100 100 100 100 92

Castor (9) 100 100 100 78 63 60 54

Neem(17) 100 100 100 100 100 85 70

5.3.9 Anti Maggot Activity (Exploratory study)

In a short term trial, the anti maggot potential of emulsion was tested in the case

of ‘Myasis’ (Development of maggotted wound caused by the larva of “Musca

domestica”). The consistent spray of Karanj & Neem oil emulsion was found to be

effective remedy for expelling maggots from the wound. The process has some added

benefits like easy handing, minimal side effects and pain free alternative. Thus, the scope

of these formulations for detailed investigation is strongly recommended.

5.4 Conclusion

Karanj, castor and neem oil were successfully formulated as stable O/W emulsion.

The correlation between various physico-chemical parameters viz. oil content, surfactant

content, HLB number of surfactant blend, hardness and emulsion stability is established

to form a series of emulsion formulations. Rheological characterization has proved their

pseudoplastic flow nature thus making them a sprayable product. These emulsions have

shown a promising activity as mosquito larvicide, house fly repellent and maggoticide.

Storage Stable OW Emulsions of Karanj.pdf

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