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

Abstract

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.

A Promising Physical Pest-Control System Demonstrated in a Greenhouse Equipped With Simple Electrostatic Devices That Excluded All Insect Pests: A Review

“…This layer is conductive (Ishay et al, 1992;McGonigle et al, 2002a;McGonigle & Jackson, 2002b;Honna et al, 2008;Moussian, 2010). Consequently, an insect that enters a static electric field is deprived of free electrons in the cuticle layer and becomes positively charged ( Figure 2D) (Kakutani et al, 2012b(Kakutani et al, , 2012cNonomura et al, 2014b). Discharge-mediated positive electrification can be induced in actual insects, as the free electrons of the cuticle layer move to ground.…”

Novel electrostatic devices for managing biotic and abiotic nuisances in environments

“…Tested insects include greenhouse pests (whiteflies, western flower thrips, green peach aphids, tomato leaf minor flies and shore flies), warehouse pests (cigarette beetles, red flour beetle, Azuki bean weevils, and rice weevils), food processing factory pests (vinegar flies and humpback flies), and house and museum pests (German cockroaches, Asian tiger mosquitoes, Oriental termites, and book louses). 68 By charging the conductor wires to 4.2 kV, the capturing force is sufficiently strong that trapped insects are not released from the trap even when blown at 7 m/s.…”

“…This idea is based on findings that the insect cuticle layer (the outer protective layer covering the body of many invertebrates) is highly conductive [89][90][91][92][93] and that free electrons in this layer are affected by an electric field. [67][68][69][70] The monitoring system can collect insect-specific signals continuously from discharge recorders set at multiple points in a warehouse. In addition to signal recognition, the correct identification of the pests is needed to determine the best way to eradicate them.…”

A Simple Electrostatic Device for Eliminating Tobacco Sidestream Smoke to Prevent Passive Smoking

“…Applied electrostatic engineering has served as the academic and technical basis for various methods that have been implemented to successfully manage pathogens and insect pests affecting agricultural crops during various stages of crop production and preservation. There are diverse ways in which electrostatic principles have been applied, which include the following: capturing spores and insects by exploiting the attractive forces generated in a static electric field (without electric discharge) [5][6][7][8][9][10]; repelling insects according to their aversion to the electric field [5,6,11,12]; disinfecting bacterial and fungal pathogens using ozone produced through streamer discharge [13]; and instantaneously dislodging fungal pathogens from plants through exposure to a plasma stream produced via a corona discharge in the electric field [14]. Based on these successful applications, we propose an electrostatic apparatus to ionize fine smoke particles with negative ions produced within an electric field.…”