Laboratory Evaluation of Toxicity of Calamus Oil Against Four Species of Stored-Product Insects²

Calamus oil, an essential oil of Acorus calamus L., was evaluated for its contact toxicity to adults of Callosobruchus maculatus (F.), Sitophilus oryzae (L.), Lasioderma serricorne (F.), and Tribolium confusum Jacquelin du Val. Topically applied, the oil was highly toxic to L. serricorne with 100% mortality at 30 μg/insect, and toxic to C. maculatus and S. oryzae with 98.3 and 61.7% mortality, respectively, at 50 μg/insect. It was nontoxic to T. confusum. When applied at a dosage of 1000 ppm to wheat or black-eyed peas, the oil completely protected them from infestation by S. oryzae and C. maculatus, respectively. The oil, at dosages of 500 and 250 ppm, still gave high protection to wheat and peas from infestation by these insects, respectively.