Phytochemical composition and molluscicidal effects of essential oil from selected plants towards pomacea canaliculata / Rohaya Ibrahim

Rice is an importance staple food in Asia. However, the rice production is insufficient because of major infestation by golden apple snail (GAS), Pomacea canaliculata. Mollucicides is the common chemical control method to control GAS which practiced by farmers because of their effectiveness and rapid effect. However, chemical molluscicides has caused hazard effect to applicators and environments. The botanical pesticide has become one of the best alternatives to reduce dependency on chemical pesticide in controlling GAS in rice fields. The characteristics of botanical pesticide was naturally degraded, different mode of action on target pest and no toxic residue after application make it the best alternative for GAS control. There were seven selected plants were studied for their effectiveness as botanical pesticides for controlling GAS to reduce dependency on chemical pesticide which are Cymbopogon citratus (lemongrass), Pandanus amaryllifolius (Pandan), Piper betle L. (betel), Curcuma longa (turmeric), Centella asiatica (Pennywort), Citrus aurantifolia (key lime) and Sauropus androgenus (Cekur manis). The aims of this research are to determine the active compounds from selected essential oils, to identify mode of action of selected plant essential oils and to compare the effective mode of action from selected plant essential oils towards controlling GAS. The qualitative analysis was screen for active compounds using Thin Layer Chromatography (TLC) and Gas Chromatography Mass Spectrometry (GCMS) for analyse and quantify active compounds from selected essential oils. Bioassay and antifeedant activity test were done with six (6) different treatments and controls. Mortality data analysed for ANOVA by SAS and antifedant was calculated using Antifeedant Index (AFI). From GCMS analysis result, four essential oils resulted with highest active compounds of citral, eugenol, α-phellandrene, turmerone, and limonene, has potential as GAS control. These four plants are fresh extract of lemongrass, Betel, turmeric essential oils and commercial essential oil of key lime were proceed for bioassay and antifeedant activity test towards GAS. Based on the LC50 value, betel essential oil is the most effective treatment for GAS mortality followed by lemongrass essential oil. The recommended treatment concentrations for betel essential oil was 0.057g/ml. While, lemongrass essential oil 0.09g/ml could be applied for GAS control on rice fields. Antifeedant activity test showed betel essential oil as most effective antifeedant source as it resulted with the highest AFI value (40.27%) and GAS mortality (58%) after 7 days of treatment exposure. Betel essential oil also resulted with highest GAS weight loss (58%) while giving lowest paddy weight loss (19.19%). Further study using commercial essential oils should be conducted by selecting pure essential oils which are higher in quality. The study for essential oil as potential botanical pesticide should be done further, with effective methodology and formulation suitable for field test, as natural compounds have limitation in term of compound stability outside the control laboratory conditions.