The Evaluation of the efficacy of Bio-pesticides produced from the Leaves of the Calotropis gigantea (Madar) Against the Oebalus poecilus (Small Rice Stink Bug)
Isaiah Willis1, Donessa David, Gomathinayagam Subramanian

Abstract
The cultivation of rice in Guyana dates to the 1800s. In fact, the climatic conditions in Guyana are ideal for rice cultivation in both summer and spring times. The Agricultural sector, which rice farming contributes heavily to, accounts for approximately a fifth of the nation’s Gross Domestic Product (GDP). Farmers have been using synthetic pesticides in the rice industry for over 75 years to maintain and/or improve the yearly crop yield. The most important pest to rice crops was identified as the small rice stinkbug or paddy bug. To combat this pest, most farmers in Guyana use synthetic pesticides which can have a harmful effect on the natural environment. This study was conducted to evaluate how effective a bio-pesticide produced by using Calotropis gigantea against field collected small rice stink bugs (Oebalus poecilus), in hopes to replace synthetic pesticides. The test insects were collected using a net to sweep across the field, as well as hand picking and were then stored in a perforated zip-lock bag. Two bio-pesticides were formulated, an ethanol extract and a water extract. The insecticidal abilities of both extracts were tested by using the film method. This is when a small amount of bio-pesticide is placed in a glass container and swirled around slowly until the entire surface area is coated. Both extracts had 100% mortality, but the difference came with the time taken for effects to be observed. The entire experiment was set for a duration of 24 hours. The ethanol extract accomplished its 100% mortality in under 30 minutes while the water extract gained its 100% mortality in under 8 hours. However, ethanol without the presences of the madar extract also gain 100% mortality, but using distilled water was completely harmless against the small rice stink bugs. Therefore, the madar plant extracts have insecticidal capabilities against the small rice stink bug.

Full Text: PDF