Effect of Acorus calamus (L.) (Araceae) oil and its main compound β-asarone on Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae)

The essential oil of Indian Acorus calamus (L.) shows potential for stored-product pest control. Its active ingredient, β-asarone, has toxic and sterilizing effects. Prostephanus truncatus (Horn) was imported to Africa in the 1970s from Central America. Now, the beetle is widely spread in Africa where a large amount of harvested maize is attacked. An environmentally acceptable and economic control method is sought. For this purpose Acorus calamus oil and β-asarone were tested as possible control agents. For direct treatment, corn grains were covered with acetone solutions of the oils. After evaporation of the solvent, the grains were apportioned and infested with beetles. Additionally, grains were treated with rhizome powder of A calamus. The damage was calculated on the weight of corndust received from the infested grains. A treatment with only 0.01% oil reduced grain loss significantly within 21 days, the amount of feeding being lowered to 50% compared to the control. After treatment with β-asarone vapours a strong depression of feeding was observed between 21 and 42 days after treatment. The temperature was very important and this effect was observed at 30°C but not 25°C. An admixture of Acorus calamus rhizome power to te corn reduced feeding activity by up to 83%.