Background: This study aimed to optimize the conditions of microwave assisted hydro distillation (MAHD) for maximizing the essential oil yield and DPPH radical scavenging activity from Alpinia blepharocalyx K. Schum. leaves. 
 
Methods: Using the central composite design (CCD) of response surface methodology (RSM) with factors that affect the yield of essential oil and DPPH obtained: Microwave power (W), liquid-to-material ratio (mL/g) and extraction time (min). 
 
Result: The optimal extraction conditions determined by the RSM model were a microwave power of 600 W, a liquid-to-material ratio of 7.0:1 mL/g and an extraction time of 45 min. Under these conditions, the experimental essential oil yield was 3.35&plusmn;0.02% and the DPPH antioxidant activity was 87.05&plusmn;0.05%. The chemical composition of the essential oil was also characterized by gas chromatography-mass spectrometry (GC-MS), revealing &beta;-Pinen, 1,8-Cineol and &alpha;-Pinen as the major compounds.

Optimization of Microwave Assisted Hydro Distillation for Enhanced Essential Oil Extraction and Antioxidant Activity from Alpinia Blepharocalyx K. Schum. Leaves

Background: The utilization of plant-based pesticides derived from clove&rsquo;s leaf and galangal represents a potential alternative for pest control, offering relative environmental safety, particularly in the case of Nilaparvata lugens (Stal.) infestations on rice plants. The objective of this study was to determine the optimal formulation of a plant pesticide based on clove&rsquo;s leaf and galangal extracts for effective management of N. lugens on rice plants.&nbsp;&nbsp; 
 
Methods: The research was conducted at the Green House of the Pest and Plant Disease Department, Faculty of Agriculture, Sam Ratulangi University, Manado. Six different concentrations of clove&rsquo;s leaf pesticide and galangal were used, each with four replications. These concentrations were 2 ml/L, 4 ml/L, 6 ml/L, 8 ml/L, 10 ml/L, and a control group. The parameters measured included nymph mortality at 12, 24, 48, and 72 hours after pesticide application. The application of the pesticide employed three methods: insect spraying, plant spraying, and insect-on-plant spraying.&nbsp; 
 
Result: Our investigations indicated that insect spraying with clove leaf pesticide resulted in a mortality rate of 43.3% to 93.3%, while galangal-based pesticide caused a mortality rate of 13.3% to 80%. Plant spraying with clove&rsquo;s leaf pesticide led to a mortality rate of 6.7% to 46.7%, and galangal-based pesticide resulted in a mortality rate of 6.7% to 40.0%. Insect-on-plant spraying caused mortality rates of 46.7% to 86.7% for clove&rsquo;s leaf-based pesticide and 50% to 76.7% for galangal-based pesticide at 12 to 72 hours after application. The highest efficacy in terms of the quickest insect mortality occurred at a concentration of 10% using the insect spraying and insect-on-plant spraying methods, with mortality observed at 12 hours after application. The slowest response was observed at a concentration of 10% using the plant spraying method, with mortality occurring at 48 hours after application. The LT50 values for 10% clove&rsquo;s leaf and galangal applications were determined as 18.2 hours and 24.6 hours, respectively. Therefore, clove&rsquo;s leaf and galangal-based plant pesticides can serve as viable alternatives to synthetic pesticides for the management of N. lugens, a pest of rice plants.&nbsp;

Effect of Methanolic Extracts of Clove (Syzygium aromaticum L.) Leaves and Galangal (Alpinia galanga L.) Rhizome for the Management of Rice Brown Plant Hopper, Nilaparvata lugens (Stal.)