Practical Application of an Electric Field Screen to an Exclusion of Flying Insect Pests and Airborne Fungal Conidia from Greenhouses with a Good Air Penetration

Abstract

In an attempt to control pathogens and insect pests affecting greenhouse tomatoes, we evaluated an electric field screen to create an airy greenhouse condition that successfully excluded insect vectors (whiteflies, green peach aphids, western flower thrips and shore flies) of pathogens and airborne conidia of tomato powdery mildew. The screen consisted of three parts: 1) insulated conductor wires (ICWs) arrayed in parallel at 5-mm intervals, 2) two stainless-steel nets that were grounded and placed on both sides of the ICWs, and 3) a direct current (DC) voltage generator to negatively charge the ICWs. An electric field formed between the negative surface charge of the ICWs and the positive charge on the ICW-side surface of the grounded net. The ICWs captured insects and airborne conidia that entered the field. Insects that contacted the outer surface of the screen net avoided the electric field and flew away from the screen. During continuous 3-month greenhouse operation, the screen was durable and functional in exerting stable pest exclusion and good air penetration for ventilation under changing greenhouse climate conditions. In three experiments examining the occurrence of powdery mildew in www.ccsenet.org/jas Journal of Agricultural Science Vol. 4, No. 5; 2012 ISSN 1916-9752 E-ISSN 1916 52 hydroponically cultured tomato plants on either side of a greenhouse partition, the screen-guarded plants remained germ free throughout the culture period (1 month), whereas powdery mildew was present on the leaves of almost all unguarded tomato plants. Thus, our electric field screen provided an airy condition for tomatoes in an open-window greenhouse that successfully excluded airborne pathogens and flying insect pests.

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

“…Despite the success of an electric field in pathogen control, a preliminary attempt to utilize this device for pest control was unsuccessful, because the electrostatic force of the spore precipitator was insufficient to retain trapped adult whiteflies. Successful application of the electric field screen enabled the management of whiteflies and other greenhouse pests (Kakutani et al, 2012a;Takikawa et al, 2016;Nonomura et al, 2012;Kakutani et al, 2017).…”

Novel electrostatic devices for managing biotic and abiotic nuisances in environments

“…The second application is a construction of an electrostatic nursery cabinet (ENC) ( Figure 2C) 38 and electrostatic seedling shelter (ESS) ( Figure 2D-Figure 2E), [12][13][14][15] which are placed in a non-guarded greenhouse. The ENC is a rectangular cabin whose three lateral walls are furnished with DD-screens ( Figure 1E) and ceiling is covered with a transparent vinyl sheet ( Figure 2C).…”

“…[9][10][11] We thus have developed new physical electrostatics-based control measures to prevent the spread of the disease. [12][13][14][15] Blue mold (by several species of genus Penicillium) is a common postharvest disease on fruit crops worldwide. This disease is an economic concern not only to the fresh-fruit industry but also to the fruit-processing industry.…”

A Promising Physical Pest-Control System Demonstrated in a Greenhouse Equipped with Simple Electrostatic Devices that Excluded all Insect Pests

“…Although breeding pathogen-resistant traits is the conventional method used to protect crop plants from disease [7][8][9], we need to remain alert to outbreaks of new pathogenic strains of the pathogen on resistant tomatoes [10][11][12]. Therefore, we developed new physical electrostatics-based control measures to prevent the spread of the disease [4,[13][14][15].…”

“…Initially, the test apparatus was conceived as a new device for capturing airborne spores of phytopathogenic fungi during crop cultivation in greenhouses [16]. Physical methods, especially those exploiting electrostatic phenomena, can generate physical forces sufficiently strong to catch airborne fungal spores [17] or small flying insects that may pass through the conventional insect netting used to protect greenhouse crops [14,15,[18][19][20][21][22]. If an effective force could be generated, an electrostatic approach would be an extremely promising tool to provide a spore-free, pest-free space for crop plants in greenhouse environments ( Figure 1A).…”