Effects of Melia azedarach on nutritional physiology and enzyme activities of the rice leaffolder Cnaphalocrocis medinalis (Guenée) (Lepidoptera: Pyralidae)

Laboratory assays were done to evaluate the effect of Melia azedarach L. (Rutales: Meliaceae) seed extract on nutritional indices and gut enzymes acid phosphatases, alkaline phosphatases, adenosinetriphosphatases, and lactate dehydrogenase of the rice leaffolder (RLF) Cnaphalocrocis medinalis (Guenée) (Lepidoptera: Pyralidae). Larvae were fed a treated rice-leaf diet containing the seed extract and their midgut was used for enzyme determination. Laboratory experiments showed that the seed extract suppressed the larval activity of C. medinalis even at a low dose. Gross dietary utilization (efficiency of conversion of ingested and digested food) of RLF decreased after ingesting the treated rice-leaf diet. Food consumption, digestion, relative consumption rate, efficiency of conversion of ingested food, efficiency of conversion of digested food, and relative growth rate values declined significantly. As compared to the control, consumption of the extract containing rice-leaf diet resulted in a 69% reduction of the acid phosphatases activity, a 71% reduction of the alkaline phosphatases activity, a 46% reduction of the adenosine triphosphatases activity, and a 52% inhibition of the lactate dehydrogenase activity.