Potential of Curcuma longa and Cymbopogon citratus as botanical pesticides for controlling Apple Snails, Pomacea Canaliculata / Siti Hawa Puteh Mansur

Apple snail, Pomacea canaliculata is an invasive species that seriously affects rice cultivation in many Asian countries and a major pest that leads to the declining of rice productivity in Malaysia. The application of synthetic molluscicides on apple snails in paddy fields resulted in negative impacts on the environment and human health. Botanical pesticide is a potential alternative way to combat apple snails. Their biodegradable, specific target and safe characteristic have prompted many researchers based on botanical pesticides. The objectives of this research are to quantify terpenes
content from Curcuma longa and Cymbopogon citratus plants extracts using Gas Chromatography Mass Spectrometry (GCMS) and to compare the most effective Curcuma longa and Cymbopogon citratus plants extract in controlling apple snails. The leaves and rhizomes of Curcuma longa and Cymbopogon citratus were extracted using methanol and ethanol solvents respectively. The extracts were tested on apple snails for five concentrations ranging from 10,000 ppm until 50,000 ppm. The time recorded for mortality and antifeedant test of apple snail from 24, 48, 72, and 96 hours. The phytochemical screening and active compound in leaves and rhizomes Curcuma longa and Cymbopogon citratus was tested by using Salkowski test to show
terpenes cpmpound and Gas Chromatography Mass Spectrometry (GCMS) respectively. GCMS results showed that the main chemical compounds in the leaves and rhizome of Curcuma longa was α-phellandrene and turmerone respectively while for leaves and rhizomes of Cymbopogon citratus was α-citral and Selin-6-en-4α-ol respectively. The results from the mortality test conducted showed that the methanol extraction for rhizomes of Curcuma longa was effective in controlling apple snails, resulted in the highest mean percentage (84%) of apple snail’s mortality during the toxicity test. The methanol solvent is the best solvents compared to ethanol solvent proven by low LC50 value against apple snail. The LC50 values (20,960 ppm) of methanol solvents for rhizomes of Curcuma longa were suggested to be applied for apple snails’ control. The correlation coefficient between mortality of apple snails, antifeedant index and feeding deterrent for all treatments was due to the significant increase of time exposure. Based on the findings of this study, methanol extractions
for rhizome of Curcuma longa was recommended for apple snails’ control and is potential to be formulated as botanical pesticides. Therefore, further analysis should be carried out to formulate the botanical pesticides based on rhizomes of Curcuma longa and be tested for field testing.