THE EFFICACY OF DIFFERENT CONCENTRATIONS OF TUBLI (Derris elliptica) CRUDE ROOT EXTRACT AGAINST RICE BLACK BUG (Scotinophara coarctata Fab.)

This laboratory experiment was studied and conducted on June to August 2020 at the College of Agriculture, Mindanao State University - Fatima Campus, General Santos City, following a completely randomized design with five treatments (1.2% tubli crude root extract concentration, 2.4% tubli crude root extract concentration, 3.6% tubli crude root extract concentration, and commercial Cypermethrin), this aimed to determine the mortality rate of Rice Black bugs (RBB) as affected by the application of different concentrations (1.2%, 2.4%, 3.6%) of Tubli (Derris elliptica) crude root extract in comparison to that of commercial (Cypermethrin) and to establish lethal concentration levels (LC50 and LC99) for aqueous tubli crude root extract and compare results with other concentrations of tubli crude root extract. The study was also designed to calculate lethal time frames (LT50 and LT99) for test and projected concentrations of tubli crude root extract and compare results with lethal time frame for commercial Cypermethrin. Results show that there are highly significant differences among daily survival rates of RBB throughout the study duration. T5 (Cypermethrin) induced the lowest survival rate, while among test concentrations T4 induced the least survival rate throughout the study duration, although it was still considerably greater than Cypermethrin. On the other hand, results revealed highly significant differences among treatments for final mortality, with cypermethrin treatment inducing the most mortality at 100%, followed by a treatment of 3.6% tubli crude root extract at 71.78%. T3 only induced a little over median mortality with 51.81%. Finally, T2 and T1 on the other hand, with the lowest mortality rate, were statistically comparable at 11.75% and 4.54% respectively. LC50 & LC99 analysis of water macerated tubli crude root extract was 25.63 g/L and 94.68g/L respectively. Comparative analysis of emulsifiable concentrate and tubli crude root extract showed that LC99 for emulsifiable concentrate was observably lower and has lesser product weight per 300-liter spray volume. On the other hand, analysis for LT50 and LT99 (lethal time frames) for projected concentrations (LC50 and LC99) revealed that LC99 for tubli crude root extract was observably lesser than LT99 of cypermethrin Although results show that test concentrations pale in comparison to that of commercial control, it can be established that once optimized, water-macerated tubli crude root extract may prove to be highly antagonistic to RBB in a considerably short time frame.