Abstrato

Selective electrostatic eradication of Sitophilus oryzae nesting in stored rice.

Matsuda Y, Takikawa Y, Nonomura T, Kakutani K, Okada K, Shibao M, Kusakari S, Miyama K, Toyoda H.

We devised a simple electrostatic apparatus to selectively kill nesting rice weevils (Sitophilus oryzae), the most destructive pests of stored grains, seeds, and grain products. The apparatus consisted of two parallel stainless steel nets and external insulator boards. One net (CN) was linked to a direct-current voltage generator to supply a negative charge; the other net (EN) was linked to a grounded line. The negative charge on the CN positively polarized the EN through electrostatic induction, forming an electric field between the nets. Electrostatic discharge from the CN depended on the distance between the nets (pole distance) and the voltage applied to the CN. Adult rice weevils were introduced into the electric field between the nets, which were charged to the maximum voltages possible without triggering electric discharge in the CN. Once the insects were introduced, they were subjected to instantaneous and transient electric current by an arc discharge from the CN, and violently ejected from the electric field. These insects were electrocuted, and the number of dismembered insects increased as the applied voltage increased. This exterminatory effect was similarly detected when a mixture of rice grains and insect pests was introduced into the electric field. Pests were selectively electrocuted within the apparatus due to the high conductivity of the insect cuticle and the insulative properties of rice grains. The proposed system is simple and easy to construct, and its scale can be enlarged through the use of larger nets, corresponding to the volume of rice grains. Thus, the present study provides an experimental basis for the practical application of an electrostatics-based pest control method.