Brine Shrimp Lethality Test and Statistical Analysis
Artemia salina eggs were obtained from Mindanao State University- Naawan Campus. Eggs were dehydrated in distilled water for 30 minutes. The tank filled with filtered sterile water was then divided into two compartments. The hatching chamber was covered with black cardboard before adding the dehydrated eggs of A. salina. The other half of the tank was illuminated to attract and separate the hatched shrimp from the unhatched eggs. The light is important to simulate the temperature of the natural habitat of the shrimp. The shrimps were then used for bioassay after 24 h.
Three replicates for each concentration were prepared. Ten A. salina nauplii larvae were transferred into each sample vial using glass dropper and filtered sterile seawater was added to make a total volume of 5 ml. Nauplii were counted macroscopically after 24 h and the deaths at control and each dose level were determined.
After 24 h, the lethal concentrations of F. nota extract resulting to 50% mortality of the brine shrimp (LC50) were determined. By means of a trendline fit linear regression analysis (MS Excel version 7) the dose-response data were transformed into a straight line. From the best-fit line obtained, the LC50 was derived.