Larvicidal Action Of Four Indigenous Plant Biology Essay

Published:

The world flora possesses a variety of plants having potential biocidal activities. This quality increased the demand of plant extracts. The present study was conducted to evaluate four plant extracts against 3rd instar larvae of Aedes aegypti. The mortality counts (LC50) were made after 24, 48, 72 and 96 hrs whereas time mortality (LT50) was recorded at different concentration (10, 5, 2.5, 1.25, 0.75 and 0.37 %). Results indicate that the extract from Citrus sinensis was more effective having lowest LC50 (LC50 = 71.83, 7.28, 2.43 and 0.84, at 24, 48, 72 and 96 hrs, respectively) followed by Azadirachta indica, Eucalyptus cameldulensis and Datura stramonium. However, lethal time (LT50) on larvae of Aedes aegypti showed the same order of potency as mentioned above. Generally speaking, the doses are directly proportional to the time interval. Our study suggested that citrus extracts are more potent and effective in managing the population of dengue vector; Aedes aegypti. Further, research needed to identify, the probable role of extract as ovicide, anti-feedant, repellence and adulticidal agent.

Lady using a tablet
Lady using a tablet

Professional

Essay Writers

Lady Using Tablet

Get your grade
or your money back

using our Essay Writing Service!

Essay Writing Service

Keywords: Aedes aegypti, plant extract, lethal concentration and lethal time.

Introduction:

Insect-transmitted diseases remain utmost concern of illness and deaths globally (Pavela, 2009). Among these insects mosquitoes are one of important group that put chaos in the public sector (Rahuman et al., 2008). These act as a bridge between pathogens (virus, nematode, bacteria etc.) and exposed host (human, animal and pets). Mosquito transmitting diseases such as malaria, dengue, filariasis and yellow fever etc., prevailed significantly in tropical countries by enforcing death, poverty and social debility every year (Borah et al., 2010). Among mosquitoes species, Ae. aegypti regarded as the primary vector of dengue virus causing dengue fever (DF) and dengue hemorrhagic fever (DHF), widely distributed in different zones (tropical and sub-tropical) of the world (Jehan et al., 2011). Generally speaking, more than 2.5 billion people are living at the risk and 80 million are infected annually (Guzman and Vazquez, 2010). At present, no vaccine is available for the prevention or control of DF and DHF, so the only solution of disease lies in the control of mosquitoes (Murrell et al., 2011). The most effective means to curtail mosquito infestation, is the use of chemicals i.e. larvicides and adulticides. The former has long lasting and better results than latter because of the application of compound at proper breeding target site (Chavasse and Yap, 1997). On the other hand, synthetic chemicals, though, have urgent results but are non selective and broad spectrum by posing hazards (Omena et al., 2007) of toxicity (in human, pets, animals and environment) and resistance (in mosquitoes). These major issues diverted our focus to new world i.e plant kingdom. The extracts or oils obtained from plant are cost effective, safe, target specific and easily biodegradable in nature (Murugan et al., 2007, Borah et al., 2010, Hafeez et al., 2010 and Hafeez et al., 2011). Focusing on this point, four indigenous plants (C. sinensis, A. indica, E. cameldulensis and D. stramonium) are selected to test their larvicidal properties against 3rd instar of Ae. aegypti.

Materials and Methods:

Collection of mosquitoes:

Immature larvae were collected from Faisalabad by a standard dipper (350 ml). The larvae were kept for adult emergence, at 28±2° C temperature and 60±5% relative humidity in the laboratory of department of Agricultural Entomology, University of Agriculture, Faisalabad. The Ae. aegypti were later mass reared and their larval stages were fed on fish food (Tetra; made in Germany). Adults were kept in plastic cages where they were provided 10% sucrose solution. The adult females were fed on blood meal of white rats (Barnard et al., 2006 and Hafeez et al., 2011) for egg laying.

Preparation of extracts:

Peels of C. sinensis, leaves of A. indica, E. cameldulensis and D. stramonium, were taken from market and Botanical garden, University of Agriculture, Faisalabad. The peels and leaves were shade dried for 48 hours and then ground (Electric grinder; Anex Germany). The material, obtained was put in soxhlet apparatus for oil extraction (using di-ethyl ether as a solvent). After 4 hours, so-called oil was collected in small vials and then stored in refrigerator for bioassay. Stock solutions were prepared by adding 1 ml of oil from each variety in 100 ml of acetone that was considered as 1% stock solution from which series of concentrations (10, 5, 2.5, 1.25, 0.75 and 0.37 %) were prepared (Muthukrishnan and Pushpalatha, 2001).

Bioassay: The oils were used in six serial concentrations (10, 5, 2.5, 1.25, 0.75 and 0.37 %). 1 ml of acetone was mixed with 149 ml of distilled water, for control treatments. There were five replicates for each treatment; each replicate containing 150 ml of the oil solution placed in 200 ml glass beakers. Twenty 3rd instar larvae of Ae. aegypti were placed in each beaker with respective concentration. The experiment was conducted under lab conditions (28± 2 ° C temperature and 60± 5% relative humidity) using CRD. The numbers of dead larvae were counted after 24, 48, 72 and 96 hours.

Data analysis:

Lady using a tablet
Lady using a tablet

Comprehensive

Writing Services

Lady Using Tablet

Plagiarism-free
Always on Time

Marked to Standard

Order Now

The data recorded was corrected by Abbot's formula (Abbot, 1925). Then the data was analyzed by Probit analysis (Finney, 1971) to calculate the medium lethal concentration (LC50) and lethal time (LT50), using Minitab 15 (Minitab Inc., 2006). The significant differences of 95% fiducial limits were calculated by non-overlapping basis. The percent mortalities were analyzes with Statistix version 8.1. Means were compared with least significant difference (LSD) test at 5% level of significance.

Results:

The plant extracts were subjected to 3rd instar larvae of Ae. aegypti, under lab conditions. Out of four extracts tested, C. sinensis possessed huge potential having lowest lethal concentration for killing the 50 % of population at 24, 48, 72 and 96 hrs (71.83, 7.28, 2.43 and 0.84 %, respectively), followed by extracts of A. indica, E. cameldulensis and D. stramonium. (Table 1) But the extract collected from D. stramonium proved more effective than E. cameldulensis at 48 (LC50 = 35.1 and 62.98, respectively) and 72 hrs (LC50 = 13.03 and 17.03, respectively). However, the order of potency is same for time intervals (24 and 96 hrs). The Chi square (χ2) values for larval mortality tests show no heterogeneity in all the experiment.

In terms of lethal time to kill 50 larvae, again C. sinensis took minimum time (25.24 hrs), followed by D. stramonium (40.21 hrs), A. indica (41.77 hrs), E. cameldulensis (55.41 hrs), at 20 % concentration. The order of lethal time changed C. sinensis, A. indica, E. cameldulensis and D. stramonium, for next serial concentration (10, 5, 2.5, 1.25, 0.75 and 0.37 %). On an overall basis, the higher concentration of each plant extract took less time to kill the larvae and vice versa.

After 24 hrs, C. sinensis exhibited highest mortality (45 %), followed by A. indica (38 %) D. stramonium (37 %) and E. cameldulensis (33 %). The order of potency changed C. sinensis, A. indica, E. cameldulensis and D. stramonium, after 48, 72 and 96 hrs (Fig. 1).

The toxicity of each extract was increased with the exposure of time. That's why after 96 hrs highest mortality of each was recorded and in contrast lowest was recorded after 24 hrs of observations.

Discussion:

C. sinensis displayed excellent potential in suppressing the larval population of Ae. aegypti. Earlier scientist (Mwaiko, 1992, Mwaiko & Savaeli, 1994, Murugan et al., 2007 and Din et al., 2011) worked in different parts of world but found same results that citrus extracts have insecticidal properties that are active in larvae as well as adult stage of target mosquito in terms of killer or repeller. Furthermore, these plant based products are found safe for human beings. However, Chansang and his co-researchers (2005) recorded highest larval mortality of Culex quinquefasciatus, from petroleum ether extract of Abutilon indicum, including four more medicinal extracts , Aegle marmelos, Euphorbia thymifolia, Jatropha gossypifolia and Solanum torvum, tested with different solvents. In India, Toddalia asiatica fruit and leaf extracts made in solvents (haexane, acetone and methanol) and found that fruit extracts are more effective than leaf (Borah et al., 2010). The superiority of fruit extracts might be based on the presence of some additional compounds that contributes greatly in the insecticidal properties of these extracts.

Moreover, limonin and Nomilin are the main contributors of bitterness in citrus, have great potential in suppressing the immatures of Ae. albopictus (Hafeez et al., 2011).

Our results clearly indicate that extracts from citrus plant are far more toxic for larval population of Ae. aegypti, endorsed by larval mortality (LC50, LT50 and percent mortality) in lesser concentration with minimum time interval. These plant derivatives (Mathur, 2003) are rich source of some primary as well as secondary metabolites that added impact in the potential of the extract. The metabolites might be used in the future mosquito control strategy.

So it is suggested to use medicinal plant parts like leaf, seed, peel, succulent branches etc for the control of dengue mosquito. Furthermore, these products are the best and target specific in terms of stomach, contact or systemic poison. More research must be needed to evaluate these plant products in semi-natural and then field conditions as well as extracted with other solvent such as hexane, methanol, acetone etc.

Table 1. LC50 values of four plant extracts against 3rd instar larvae of Ae. aegypti

Varieties

Observations

(hrs)

LC50

(%)

95 %

FL

Slope +

S.E

χ2

(df = 5)

Citrus sinensis

24

48

72

96

71.83

7.28

2.43

0.84

25.89 - 693.11d

Lady using a tablet
Lady using a tablet

This Essay is

a Student's Work

Lady Using Tablet

This essay has been submitted by a student. This is not an example of the work written by our professional essay writers.

Examples of our work

4.83 - 13.02c

1.67 - 3.49b

0.48 - 1.24a

0.18 + 9.93

0.25 + 1.73

0.26 + 0.43

0.27 + 0.19

0.79

3.87

4.64

3.08

A. indica

24

48

72

96

82.17

21.64

4.51

1.32

29.13 - 809.31cd

10.42 - 98.07c

2.81 - 8.42b

0.61 - 1.92a

0.19 + 9.17

0.18 + 10.57

0.19 + 1.16

0.20 + 0.32

1.61

1.07

0.50

0.27

E. cameldulensis

24

48

72

96

427.62

62.98

17.03

2.76

81.01 - 4014cd

23.61 - 542.2bc

8.47 - 70.1b

1.71 - 4.52a

0.17 + 7.32

0.19 + 6.75

0.17 + 7.89

0.21 + 0.64

0.67

0.30

0.73

1.47

D. stramonium

24

48

72

96

254.2

35.1

13.03

4.39

67.5 - 522.47cd

17.7 - 118.8bc

7.84 - 29.73b

3.03 - 6.95a

0.21 + 7.39

0.24 + 15.52

0.23 + 4.09

0.25 + 0.88

3.84

7.63

8.18

3.02

*LC50 data recorded within an extract treatment denoting the same letters are not different at the 5% level of significance. FL, fiducial limit is the upper and lower limits of respective LC50 values

Table 2. LT50 values of four plant extracts against 3rd instar larvae of Ae. aegypti

Varieties

Observations

(%)

*LT50

(hrs)

95 % FL

Slope +

S.E

χ2

(df = 3)

C. sinensis

0.37

0.75

1.25

2.50

5

10

20

126.13

124.99

99.41

77.49

58.82

37.81

25.24

93.34 - 209.7de

91.29 - 214. 84de

76.39 - 151.05d

61.52 - 108.4cd

48.11 - 75.87c

31.39 - 45.23b

20.26 - 30.14a

0.57 + 23.9

0.54 + 24.9

0.56 + 16.07

0.57 + 10.54

0.58 + 6.53

0.64 + 3.41

0.68 + 2.47

0.53

0.66

1.29

1.55

2.13

1.80

3.58

A. indica

0.37

0.75

1.25

2.50

5

10

20

169.46

122.59

111.28

74.54

65.64

50.83

41.77

118.02 - 326.12def

92.35 - 195.40cde

82.56 - 184.23cd

57.87 - 109.20bcd

51.97 - 91.00abc

40.96 - 65.66ab

33.26 - 52.88a

0.58 + 39.80

0.70 + 21.71

0.52 + 20.87

0.49 + 11.19

0.51 + 8.79

0.52 + 5.82

0.51 + 4.71

1.09

0.38

0.78

1.01

0.58

2.09

3.86

E. cameldulensis

0.37

0.75

1.25

2.50

5

10

20

210.34

184.30

171.65

133.87

107.41

73.39

55.41

137.09 - 482.41cdef

124.02 - 387.80cde

114.43 - 373.93cd

94.61 - 248.12bcd

80.98 - 170.89bc

60.24 - 96.00ab

45.47 - 70.54a

0.55 + 59.96

0.54 + 48.03

0.49 + 46.05

0.54 + 29.62

0.54 + 18.88

0.64 + 8.33

0.58 + 5.94

0.97

1.95

2.19

1.26

1.01

1.45

2.66

D. stramonium

0.37

0.75

1.25

2.50

5

10

20

283.76

282.91

220.69

168.19

122.20

95.59

40.21

166.67 - 684.51cdef

162.68 - 546.80cde

136.19 - 599.93cde

122.51 - 363.69bcd

90.67 - 201.70bc

74.73 - 139.60b

33.16 - 48.73a

0.52 + 80.43

0.48 + 78.23

0.47 + 72.43

0.49 + 44.70

0.56 + 22.94

0.59 + 14.27

0.61 + 3.81

0.20

1.01

0.59

1.04

1.25

1.97

0.19

*LT50 data recorded within an extract treatment denoting the same letters are not different at the 5% level of significance. FL, fiducial limit is the upper and lower limits of respective LT50 values

Figure 1. Bars are mean percent mortality (± S.E.) at different time intervals with their respective concentrations. Bars sharing the same letters are not significantly different at the 5% level of significance.