Journal of Environmental Treatment Techniques                                 Download PDF version

2018, Volume 6, Issue 2, Pages: 36-39

J. Environ. Treat. Tech.

ISSN: 2309-1185

Journal web link: http://www.jett.dormaj.com

Control of Mosquito Larva Using Bark Extracts of

Gmelina arborea

Godbless N Oyinke1, Odangowei I. Ogidi2, Odigo C. Konmeze2

1Department of Biological Sciences, Niger Delta University, Wilberforce Island, Bayelsa State, Nigeria.

2Department of Science Laboratory Technology, Federal Polytechnic of Oil & Gas Ekowe, Bayelsa State, Nigeria. 3Department of Science of Environmental Health Sciences, College of Health Technology, Otuogidi, Bayelsa State

Received: 10/03/2018

Accepted: 26/06/2018

Published: 30/09/2018

Abstract

The application of plant derived pesticides for the control of vectors and pathogen have become global. Notwithstanding, synthetic therapies have been most applied, but it poses some ecotoxic problem when misapplied. The biocidal activities of 3 solvent (chloroform, Methanol and Ethanol), bark extracts of Gmelina arborea was investigated against vectors of malaria (Anopheles Gambiae). Results show that the chloroform extract has LC50 value of 4.90 ppm. Furthermore, the ethanol and methanolic extracts had LC50 values of 4.00 and 2.20 ppm respectively. Therefore, the order of activities of the bark extracts of G. arborea were chloroform>ethanol>methanol. Based on results of this study, we therefore recommend the plant for the

formulation of pesticide for the control of malaria and vector-borne diseases.

Keywords: Anopheles Gambiae, Gmelina arborea, Bark extract, Solvents

1 Introduction1

Malaria is a tropical and rampant vector-borne diseases transmitted by female anopheles’ mosquito [1, 2]. Records of the WHO as documented in literature indicated that malaria ranks first amongst vector borne diseases, with significant global morbidity and mortality burden [3]. In Africa Malaria is endemic in over 40 countries, including Nigeria with over 500 million of the population at risk [4], especially children and pregnant women [5].

Gmelina arborea is a deciduous and eco-tolerant plant which belonging to the verbenaceae family. It is endemic in several continents, and thrives in vast and extreme weather conditions, especially in the tropics and Asia [6]. The therapeutic applications of the plant have already documented in literature. It generally has antibacterial and antidiabetic and antioxidant properties [7]. The root and bark extracts were effective as laxative, and also used to relief stomach ache and piles [8, 9].

Furthermore, the multifaceted nature of the G. arborea have been documented in literature including its; anti- vernominal properties, anti-schistosomal properties [10]. Also, antioxidant properties [11]. Notwithstanding, there are several challenges encountered in the fight against vector-borne disease like malaria.

Corresponding Author: Godbless N Oyinke Department of Biological Sciences, Niger Delta University, Wilberforce

Island, Bayelsa State, Nigeria. Email: maktarry@yahoo.com.

They include but not limited to the ecotoxicity of synthetic pesticides [2], re-infection after drug administration [12], as well as the rapid prolificacy of the vectors [13]. The application of synthetic pesticides against vectors that transmit diseases is not far-fetched. On the other hand, the problem associated with wrong use of synthetic pesticides can be toxic and adverse to other species [2, 3].

2 Materials and Methods

2.1Collection and preparation of plant Extract

The Bark of G. arborea was collected along Swali

Market road in Yenagoa Local Government Area of Bayelsa State, Nigeria. Three hundred grams (300 g) of fresh bark of the plant was weighed (Satoric AG Gottingen Electronic weighing balance). The weighed bark was chopped into tiny bits and pounded using clean ceramic mortar and pestle. It was then macerated in 500 ml of the respective solvents being; Chloroform, Ethanol and Methanol (BHD Chemical Ltd. Poole England) for 72 hours. Afterwards, it was filtered into a clean and sterile conical flask using whatman no.1 filter paper [14]. The filtrates of the macerated concoctions were respectively extracted using a rotary evaporator (60°C). The obtained extracts (i.e. extracted active ingredients) were allowed to cool and preserved for the bioassay at low temperature (4°C).

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Journal of Environmental Treatment Techniques

2018, Volume 6, Issue 2, Pages: 36-39

2.2Vector Collection/Breeding of Larvae

Mosquito Larvae belonging to the genus Anopheles

(An. gambiae), was used for the study. The larvae were cultured in the wild using baits positioned around conspicuous breeding sites. Plastic containers and automobile tyres half-filled with water, and sand was used as the breeding bait in conspicuous breeding site. The baits were constantly monitored for the conspicuous emergence of mosquito larvae. Prior to the bioassay, the bred larvae were placed on an enamel tray with dechlorinated water (pH 7.4), and acclimatized to laboratory condition [15, 16].

2.3Experimental Set Up

For the purpose of the bioassay, samples of 20 larvae

and snails, were distinctly placed in a 500ml solution of the extracts, in a 24-hour static non-renewal test. It was performed in accordance with the World Health Organization guidelines [17]. The mortality rates of organisms were observed and recorded. Dipex pesticide was used as the positive control, while 500ml of distilled water adjusted with 2.5 ml of 10% dimethyl sulfoxide (DMSO) at pH 7.5, was used as the negative control [12, 15].

2.4Biolarvicidal Screening Test

In a rapid screening test, triplicate concentrations of 50

-10ppm were used to screen the larva and snails for total (i.e. 100%) mortality within 24 hours in order to detect the range of activity. The replicates of the extracts which demonstrated total average mortality (i.e. 100% mortality) on larva at 10ppm during the rapid screening. The screening was carried out at different concentrations, in order to determine the minimal total lethal concentrations (LC100).

2.5Statistical Analysis

The data for mortality rates were expressed as mean±

standard deviation using version 20 of SPSS. A one-way analysis of variance was used to carry out the statistical analysis, while Duncan multiple range test was used to determine the source of observed difference using SPSS Version 20. Furthermore, the median Lethal doses (LC50) of the seed sap against the larva, were estimated from the average minimal lethal concentrations in a concentration- mortality using Microsoft 2016 excel package.

3 Results and Discussion

The mortality rates of all solvent bark extracts including Chloroform, Methanol and Ethanol, assayed against the larvae of An. gambiae are presented in Tables 1, 2 and 3. For the biolarvicidal bioassay, the positive control induced total mortality at 1.00ppm, as opposed to the negative control had no lethal or sublethal effects against all larvicidal bioassay (Tables 1 -3). However, the solvent extracts demonstrated varying degrees of mortalities at concentrations ranging from 1.00 - 10.00 ppm (p<0.05). As presented in Table 1, for the Chloroform extract bioassay, mortality rate increases with corresponding increase in concentration. Statistically there was significant difference (p<0.05) at all concentrations, with minimal lethal concentration at 10.00 ppm (Table 1).

37

Table 2 presents the mortality rates for An. gambiae screened against methanolic bark extract of G. arborea. Results of the bioassay similarly indicated that the positive control induced total mortality at 1.00ppm, whereas the negative control demonstrated no mortality against the larvae (Table 2). Furthermore, while the varying degrees of mortalities increased with concentration with significant difference (p<0.05), the minimal lethal concentration was demonstrated at 7.00ppm.

Table 3 presents the mortality rates of ethanol bark extract of G. arborea screened against larva of An. gambiae. In a similar fashion, while the negative control had no effect on the larvae, the positive control was lethal at 1 ppm. Mortality rate with increase in concentration, with minimal lethal concentration at 9.00ppm. There were significant differences amongst the various concentration, except for the minimal lethal concentration.

The activities of the solvent extracts were assayed against the larvae in a concentration-mortality curve as presented in Figure 1. The Chloroform extract had LC50 value of 4.90 ppm, a more active LC50 value of 4.00ppm was exhibited by the ethanol bark extract. Meanwhile, the highest activity was demonstrated by the Methanolic bark extract with LC50 value of 2.20ppm. While all extract of G. arborea exhibited biolarvicidal activities. The larvicidal activities are as a result of diverse bioavailable phytochemicals in the plant, phytochemicals like; saponin, alkaloid, tannin, phenol, flavonoid and the variation in activities of plant extracts are influenced by the various applied solvents [2, 18]. In another study phytochemical like; methyl arboreal, arboreal, isoarboreol, glummadiol, flavonoid, alkaloids, gmelanone, n-hexacosnol, sitostereol and hutteolin have been isolated from G. arborea [19].

Negative Control

Chloroform Extract [LC50═4.90ppm]

Methanol Extract [LC50═2.20ppm]

Ethanol Extract [LC50═4.0ppm]

 

100

rates (%)

50

Mortality

 

 

0

1

2

3

4

5

6

7

8

9

10

 

 

 

Concentration (ppm)

 

 

 

Figure 1: Concentration-mortality of express seed sap

extracts of G. arborea against An. gambiae

A recent study showed that the express seed sap extracts of G. arborea against An. gambiae was lethal with LC50 values of 2.25 ppm; as well as vectors of schistosomiasis being Bulinus globosus and B. pfeifferi with LC50 values of 0.75 and 8.00ppm respectively (Angaye et al., 2017b). In another study, using several solvents (crude, methanol, ethanol, chloroform, hexane) extracts of G arborea demonstrated significant mortality rates (Angaye et al., 2017a).

Journal of Environmental Treatment Techniques2018, Volume 6, Issue 2, Pages: 36-39

Table 1: Mortality rates for An. gambiae Chloroform Extract Larvicidal Bioassay

Concentration

 

Mortality Rates (%) Mean±SD

 

95% Confidence Interval for Mean

Minimum

Maximum

(ppm)

Chloroform Extract

 

Positive Control

Negative Control

Lower Bound

Upper Bound

 

 

0.00

0.00±0.00a

 

0.00±0.00a

0.00±0.00a

0.0000

0.0000

0.00

0.00

1.00

21.00±2.00b

 

100.00±0.00k

0.00±0.00a

16.0317

25.9683

19.00

23.00

2.00

28.00±3.00c

 

100.00±0.00k

0.00±0.00a

20.5476

35.4524

25.00

31.00

3.00

33.67±3.00d

 

100.00±0.00k

0.00±0.00a

26.0775

41.2558

31.00

37.00

4.00

44.00±3.00e

 

100.00±0.00k

0.00±0.00a

36.5476

51.4524

41.00

47.00

5.00

54.33±3.05f

 

100.00±0.00k

0.00±0.00a

46.7442

61.9225

51.00

57.00

6.00

57.33±3.06g

 

100.00±0.00k

0.00±0.00a

49.7442

64.9225

54.00

60.00

7.00

65.67±3.05h

 

100.00±0.00k

0.00±0.00a

58.0775

73.2558

63.00

69.00

8.00

83.00±4.58i

 

100.00±0.00k

0.00±0.00a

71.6163

94.3837

78.00

87.00

9.00

94.00±3.00j

 

100.00±0.00k

0.00±0.00a

86.5476

101.4524

91.00

97.00

10.00

100.00±0.00k

 

100.00±0.00k

0.00±0.00a

100.0000

100.0000

100.00

100.00

Table 2: Mortality rates for An. gambiae Methanolic Extract Larvicidal Bioassay

Concentration

 

Mortality Rates (%) Mean±SD

 

95% Confidence Interval for Mean

Minimum

Maximum

(ppm)

Methanol Extract

 

Positive Control

Negative Control

Lower Bound

Upper Bound

 

 

0.00

0.00±0.00a

 

0.00±0.00a

0.00±0.00a

0.0000

0.0000

0.00

0.00

1.00

47.00±2.00a

 

100.00±0.00g

0.00±0.00a

42.0317

51.9683

45.00

49.00

2.00

55.67±1.55b

 

100.00±0.00g

0.00±0.00a

51.8721

59.4612

54.00

57.00

3.00

60.00±1.00c

 

100.00±0.00g

0.00±0.00a

57.5159

62.4841

59.00

61.00

4.00

64.67±2.52cd

 

100.00±0.00g

0.00±0.00a

58.4151

70.9183

62.00

67.00

5.00

74.67±4.04d

 

100.00±0.00g

0.00±0.00a

64.6271

84.7062

71.00

79.00

6.00

84.33±2.08e

 

100.00±0.00g

0.00±0.00a

77.1622

87.5045

80.00

84.00

7.00

100.00±4.00f

 

100.00±0.00g

0.00±0.00a

77.0634

96.9366

83.00

91.00

8.00

100.00±0.00f

 

100.00±0.00g

0.00±0.00a

100.0000

100.0000

100.00

100.00

9.00

100.00±0.00f

 

100.00±0.00g

0.00±0.00a

100.0000

100.0000

100.00

100.00

10.00

100.00±0.00f

 

100.00±0.00g

0.00±0.00a

100.0000

100.0000

100.00

100.00

Table 3: Mortality rates for An. gambiae Ethanolic Extract Larvicidal Bioassay

Concentration

 

Mortality Rates (%) Mean±SD

 

95% Confidence Interval for Mean

Minimum

Maximum

(ppm)

Ethanol Extract

 

Positive Control

Negative Control

Lower Bound

Upper Bound

 

 

0.00

0.00±0.00a

 

0.00±0.00a

0.00±0.00a

0.0000

0.0000

0.00

0.00

1.00

34.67±1.53b

 

100.00±0.00h

0.00±0.00a

30.8721

38.4612

33.00

36.00

2.00

39.33±1.52c

 

100.00±0.00h

0.00±0.00a

35.5388

43.1279

38.00

41.00

3.00

43.67±1.53cd

 

100.00±0.00h

0.00±0.00a

39.8721

47.4612

42.00

45.00

4.00

49.00±2.00d

 

100.00±0.00h

0.00±0.00a

44.0317

53.9683

47.00

51.00

5.00

60.00±3.61e

 

100.00±0.00h

0.00±0.00a

51.0433

68.9567

56.00

63.00

6.00

71.67±2.65f

 

100.00±0.00h

0.00±0.00a

68.4276

81.5724

73.00

78.00

7.50

82.33±2.52g

 

100.00±0.00h

0.00±0.00a

78.0817

90.5849

82.00

87.00

8.00

87.00±3.11h

 

100.00±0.00h

0.00±0.00a

100.0000

100.0000

100.00

100.00

9.00

100.00±0.00i

 

100.00±0.00h

0.00±0.00a

100.0000

100.0000

100.00

100.00

10.00

100.00±0.00i

 

100.00±0.00h

0.00±0.00a

100.0000

100.0000

100.00

100.00

38

Journal of Environmental Treatment Techniques

2018, Volume 6, Issue 2, Pages: 36-39

These phytochemicals which were reported to support the bioactivities of the plant include; flavonoid, alkaloids, arboreal, isoarboreol, methyl arboreal, glummadiol, gmelanone, n-hexacosnol, sitostereol and hutteolin. The antimicrobial activities of G. arborea was also reported against some pathogenic microbes (Kaswale et al., 2012; Ishaku et al., 2012).

4 Conclusion

Three solvent bark extracts of G. arborea were investigated against mosquito larvae. Fortunately, all solvent extract shows promising larvicidal activities against the larvaes with the methanolic extract having the highest activity. Based on results of this study we therefore recommended G. arborea as a potential candidate for alternative formulation of pesticide for the control of malaria. In addition, we also recommend further study for field application of this plant.

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