Efficacy of Sarawak Piper nigrum L. (Piperaceae) Ethanolic Extract against the Development of Dengue Vector, Aedes albopictus (Diptera: Culicidae) and its Phytochemical Constituents

Emira Izzati, Abdul Aziz (2021) Efficacy of Sarawak Piper nigrum L. (Piperaceae) Ethanolic Extract against the Development of Dengue Vector, Aedes albopictus (Diptera: Culicidae) and its Phytochemical Constituents. Masters thesis, Universiti Malaysia Sarawak.

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Abstract

The emergence of insecticide-resistance mosquitoes has encouraged the search for natural insecticide from botanical origin that may become an alternative biocontrol tool in controlling mosquito population worldwide. Hence, this study is to look into the efficacy of Sarawak Piper nigrum fruit and leaf ethanolic extracts and its phytochemical constituents on the mosquito development of Aedes albopictus and the effects on its morphological abnormalities. Phytochemical screening revealed the presence of alkaloid, flavonoid, tannin, triterpenes and steroid in the fruit and leaf extracts, while saponins was only found in the leaf extract. Further GC-MS analyses revealed that a total of 79 phytochemical constituents were detected from P. nigrum fruit extract with the highest constituents were piperine, followed by caryophyllene and (e)-9-(benzo[d] [1,3] dioxol-5-yl)-1-(piperidin-1-yl) non-8-en-1-one with the remaining constituents ranged from 0.05 % to 4.56 %. Meanwhile, a total of 80 phytochemical constituents were detected from P. nigrum leaf extract with the major constituents including n-ethyl-n-furfurylaniline, cyclohexene, 4-ethenyl-4-methyl-3-(1-methylethenyl)-1, isospathulenol and furan,2-hexyl with the remaining constituents ranged from 0.11 % to 4.83 %. Both P. nigrum fruit and leaf ethanolic extracts produced a remarkable result on larvicidal activity against Ae. albopictus after 24 hours of exposurewith P. nigrum fruit ethanolic extract appeared to be more susceptible with lower LC50 at 5.070 ppm and LC90 at 7.850 ppm needed compared to leaf ethanolic extract which required higher LC50 at 108.890 ppm and LC90 at 213.796 ppm. Meanwhile, after 48 hours of exposure, both P. nigrum fruit and leaf ethanolic extracts have significantly reduced the pupation success and adult emergence of Ae. albopictus, where nearly 0.00±0.000 % to 1.00±0.500 % of pupae and adult were success to emerge at higher concentration of 10.5 ppm and 350ppm to 450 ppm for P. nigrum fruit and leaf extracts in 7 days. Both P. nigrum fruit and leaf ethanolic extracts also induced various morphological abnormalities at the larvae, pupae and adults’ stages of Ae. albopictus. Forms of the morphological abnormalities varied with concentrations of both extracts. The P. nigrum fruit and leaf ethanolic extracts excellently deterred oviposition of Ae. albopictus gravid females at all concentrations tested ranging from 50 ppm to 450 ppm as they favoured to deposit their eggs in a control ovitraps compared to treated solutions with the range of effective repellency (ER) between 63.17 % to 96.63 % (P. nigrum fruit extract) and 52.83 % to 96.56 % (P. nigrum leaf extract). Both P. nigrum fruit and leaf ethanolic extracts had also significantly elicited remarkable ovicidal potential in Ae. albopictus where the increased in the concentrations of P. nigrum fruit and leaf ethanolic extracts from 100 ppm to 500 ppm, it decreased the mean percentage of egg hatchability from 62.4000 ± 2.4083 % to 35.2000 ±1.6432 % (P. nigrum fruit extract) and from 67.2000 ± 0.9165 % to 41.6000 ± 0.5099 % (P. nigrum leaf extract), egg hatching was maintained at the highest mean of 93.0000 ± 1.6432 % in the control group. To conclude, both P. nigrum fruit and leaf ethanolic extracts had significantly elicited multiple properties as mosquito insecticidal agent, oviposition deterrent and oviciding agent in Ae. albopictus. Plus, the reduction in egg hatchability and survival rates, suggested an additional hallmark of this plant to be integrated in Aedes mosquito control. Hence, the ethanolic extracts of P. nigrum from Sarawak may lead to the development of an environmentally safe mosquito biocontrol agent. Keywords: Aedes albopictus, ethanolic extract, mosquito development, morphological abnormalities, Piper nigrum, phytochemical constituents

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