Molluscicidal Effect of Amaranthus spinosus (Urai) Leaf Extract Against Pomacea canaliculata (Golden Apple Snail)

Abstract

INTRODUCTION

Pomacea canaliculata (golden apple snail) is one of the serious pests of rice in the Philippines. Chemical molluscicides used to be able to manage this pest effectively but its harmful effects on the environment and human health pose a significant problem. This study was conducted to determine the molluscicidal effect of Amaranthus spinosus(urai) leaf extract against golden apple snails.

METHODS

Three hundred sixty snails of different sizes with shell diameters ranging from 10-28 mm were exposed to three concentrations of leaf extract (30%, 60% and 100%). Each container has 10 snails giving a total of 30 snails per treatment. Mortality of snails was determined by probing with a needle to which the snails give no response. One-way ANOVA was used to determine if there is a significant difference among the different treatments of urai leaf extract.

RESULTS

Results showed that the percentage of mortality for small-sized snail is 86.67%, 96.67%, and 100.00%, while 66.67%, 93.33%, and 96.67% for medium-sized, and 70.00%, 86.67%, and 96.67% for large-sized, for all treatments A (30%), B (60%), and C (100%), respectively. One-way ANOVA showed that the computed F-value, 3.06 (small-size), 8.47 (medium-size) and 5.66 (large-size) are greater than the critical F-value, 2.43, which indicates that there are significant differences among the different concentrations and the standard molluscicide. Using Sheffé test, it was identified that there is no significant difference in the mortality of snails for all treatments used in small-sized snails. For both medium-sized and large-sized snails, it showed that 60%, 100% concentrations and the standard molluscicide have no significant differences in terms of their molluscicidal effect.

DISCUSSIONS

Within the course of the study, the researchers have found that bioactive components such as saponin are present in the urai leaf extract. The application of organic molluscicide with saponin as bioactive component destroys the red blood cells by means of hemolysis and therefore, reduces oxygen uptake and alter hemoglobin concentration. Also, the effect of urai leaf extract against golden apple snail was observed within two days after the application which is within the 2-3 day duration of what is considered a good molluscicide. Qualitative and quantitative phytochemical analyses of the plant extract are recommended for further study to identify the actual amount of bioactive components. It is also recommended to apply the product in field testing to ensure the reliability of the extract.