Grain Protection Potential of Decaleside II, a New Plant-Derived Natural Insecticide

Decaleside II is the novel trisaccharide isolated from the edible roots of Decalepis hamiltonii that belong to a new class of natural insecticides. In the present study we have investigated grain protection potential and persistence activity of Decaleside II against stored-product pests such as Rhyzopertha dominica, Sitophilus oryzae, Tribolium castaneum and Callosobruchus chinensis. Decaleside II usually increased parental mortality and reduced F1 progeny in residual toxicity bioassays. At 7 days of the storage period of treated grains and pulses, the mortality was 100% of all four stored product insects. Both wheat and green gram treated with Decaleside II were totally free from infestation for the longer period of storage up to 210 d. Decaleside II being a natural trisaccharide, does not pose any toxic hazard from the treated grain and the lack of toxicity is attributed to the 1, 4 α linkage of the sugars which are easily hydrolyzed by the digestive enzymes such as glucosidases. Therefore, the insect selectivity and mammalian safety of Decaleside II make them highly suitable for use as novel grain protectants of natural origin.