Insecticidal Effect of Calamansi (C. microcarpa) Extracts Against Rice Weevils (S. oryzae)

Abstract

INTRODUCTION

Rice being the most common staple food in our country is threatened by insect pests during storage. Several strategies are utilized in controlling storage pests by using synthetic insecticides causing harm and damage to human health and the environment. This offers motivation in searching for more alternative methods of controlling rice pests. In recent years, several researchers have concentrated for the search for natural products that can be found from terrestrial plants as natural insecticide. Calamansi, C. microcarpa, has a major component which is called d-limonene, a bitter taste that irritate insects by destroying the wax coating of insect's respiratory system, making it as a good repellent.

METHODS

The extracts of C. microcarpa (carpel, seeds and peels) underwent through steam-distillation and d-limonene from each extract was obtained. To determine the mortality effect of the extracts on rice weevils, parallel research design was applied wherein all the groups received the treatment at the same time. The set-ups were observed for five days in 12-hour intervals to determine the mortality of rice weevils. One Way Analysis of Variance was the statistical tool applied to compare the means of the three groups of independent samples.

RESULTS

From the results of the study, the peel extract had the highest mortality among all the extracts, followed by the seed extract and lastly, the carpel extract had the lowest mortality effect on the rice weevils. This was based on the determined mortality during the experimentation. The results revealed that the extracts could terminate rice weevils and show a significant difference among the extracts in terms of its insecticidal effect against rice weevil. The researchers proved that C. microcarpa extracts can be an effective insecticide on rice weevils.

DISCUSSIONS

The study turned out successfully since the C. microcarpa extracts has a capability of terminating the rice weevils. Further studies should be conducted about investigating other parts of C. microcarpa tree, leaves or roots in terms of its insecticidal effect to see if the following parts also have an insecticidal activity against rice weevils. It is recommended that the extracts be analyzed using Gas Chromatography Analysis to determine its chemical characterization and to prove that the d-limonene is present on the fruit and to improve its methodology.