Anacardium Occidentale and Jatropha Curcas Seeds’ Alkaloids: Their Feeding Inhibitory and Growth Retardatory Potentials on Rhyzopertha Dominica

Abstract

The damaging effect of Rhyzopertha dominica larvae and adult insects on the nutritive content and economic value of Zea mais seeds, and the cytotoxic nature of most phyto-alkaloids prompted this research work to be carried out. A. occidentale and J. curcas seeds’ alkaloids were extracted and experimented for feeding inhibition and growth retardation on callow and mature adult R. dominica (Lesser grain borer) using maize seeds. Feeding inhibition for A. occidentale and J. curcas seeds’ alkaloids on adult insects were 39.40%, 49.88%, 81.37%, 100%, 47.48%, 55.12%, 93.31%, 100% respectively at 50 µg/mL, 150 µg/mL, 300 µg/mL and 400 µg/mL concentrations. Alkaloids from Jatropha curcas seeds demonstrated higher feeding inhibitory potentials than alkaloids from Anacardium occidentale seeds. Relative Growth Rates (RGR) of callow and mature R. dominica were retarded by A. occidentale and J. curcas seeds’ alkaloid treatments. The feeding inhibitory potentials of A. occidentale and J. curcas seeds’ alkaloids at 400 µg/mL concentration on both the callow and mature adult insects were translated to growth retardation of the insects when compared to maize seeds without alkaloid treatment (controls) fed by the insects . Relative Consumption Rates (RCR) of maize by callow and mature R. dominica were also reduced for maize seeds treated with alkaloids, indicating growth is a function of consumption. Thus alkaloids from Anacardium occidentale and Jatropha curcas seeds demonstrated feeding inhibitory and growth retardatory potentials on callow and mature adult R. dominica.