Insects are electrified in an electric field by deprivation of their negative charge

• Published in: Annals of applied biology 2012-05, Vol.160 (3), p.250-259
• Main Authors: Kakutani, K., Matsuda, Y., Haneda, K., Nonomura, T., Kimbara, J., Kusakari, S., Osamura, K., Toyoda, H.
• Format: Article
• Language: English
• Subjects: Bioelectric power generation; Biological and medical sciences; Conductors; Crops; Electric currents; electric field screen; Electric fields; Electricity; electrostatic attraction; Electrostatic properties; Fundamental and applied biological sciences. Psychology; Greenhouses; insect pests; Iron; Pests; Surface charge; transient bioelectric discharge
• ISSN: 0003-4746; 1744-7348
• DOI: 10.1111/j.1744-7348.2012.00538.x

An electric field screen (EF‐screen) is a physical device for excluding pest insects from greenhouses and warehouses to protect crops during their production and storage periods. In this study, a simple version of the EF‐screen, an insulated conductor iron wire (ICW) paralleled to an earthed net, was constructed to effectively observe the attraction of test insects in relation to their electricity release. The ICW was negatively charged to dielectrically polarise the insulator sleeve of the ICW: negatively on the outer surface and positively on the inner conductor wire surface of the sleeve. The negative surface charge of the ICW caused an electrostatic induction in the earthed net and a resultant positive charge at the ICW‐side surface of the net. An electric field formed between the ICW (negative pole) and earthed net (positive pole). Insects were attracted to the ICW when they were placed onto the earthed net. A vital step for the attraction was the creation of a transient bioelectric discharge from an insect. During this discharge, an electric charge of the insect was transferred to the earthed net. Eventually, the insect became net positive and was then attracted to the ICW. The magnitude of the current increased in direct proportion to the increase in voltage applied to the ICW, and the attraction force was directly proportional to the increase in the electric current. Larger voltages were necessary to attract much larger insects because larger insects were stronger and therefore more able to escape from the ICW attraction. Similar results were obtained for a wide range of pest insects belonging to different taxonomic groups (8 orders and 15 families). This study demonstrated that transient bioelectric discharge is common in insects and can be utilised to create an electrostatic force capable of moving insects in a generated electric field.