Abstract:
Laboratory experiments were conducted in the Department of Plant protection, College of Agricultural Studies, Sudan University of Science and Technology (SUST) to evaluate the lethal effect of seed ethanolic extracts of Coffee senna Cassia occidentalis L. and Damas Concorpus lancifolius Engl. against the second larval instars of the African melon ladybird Henosepilachna elaterii Rossi. Also further experiments were conducted to investigate the efficacy of sesame oil as a synergist. Five concentrations of seeds ethanolic extracts of each plant were used in this study. The results showed that all tested concentrations of both plants caused higher mortality percentage than the control. The lowest concentration (1%) of seed ethanolic extract of C. occidentalis gave only 3.3 % mortality after 24 hrs of exposure; however, when mixed with sesame oil it increased significantly to 90%. Seed ethanolic extract of C. occidentalis at 10.5% and 14% concentrations generated 90 % and 96.6% mortality respectively after 24 hrs of exposure and the results were not significantly different from Malathion.
On the other hand, the lowest concentration (1%) of seed ethanolic extract of C. lancifolius caused only 6.6% mortality after 24 hours of exposure but when mixed with sesame oil it increased significantly to 53.3% mortality. The highest concentrations of seed ethanolic extract of C. lancifolius (14% ) gave only 53.3% whereas the same concentration of seed ethanolic extract of C. occidentalis generated 100% motality after 72 hrs of exposure.
The results obtained after 72 hrs of application showed that the LC50 values were 5.584%, 0.001%, 20.596% and 0.162% for C. occidentalis, C. occidentalis + sesame oil, C. lancifolius and C. lancifolius +sesame oil respectively.
