An electric field strongly deters whiteflies from entering window-open greenhouses in an electrostatic insect exclusion strategy

Dual functions (insect repelling and capturing) of a single-charged dipolar electric field screen were evaluated to successfully exclude whiteflies from a window-open greenhouse. The screen consisted of three parts: 1) insulated conductor wires (ICWs) arrayed in parallel at 5 mm intervals, 2) two earthed stainless nets placed within 3 mm of both sides of the ICW layer, and 3) a voltage generator for the negatively charged ICWs. The screen formed two electric fields between the ICW-layer and the ICW-side surface of the earthed net and between the ICWs. At negative charging of 1.5-2.5 kV, all whiteflies reaching the outer surface of the screen net avoided entering the electric field and flew away from the screen. This avoidance was disturbed by 3 m s(-1) wind, as the insects were compulsorily blown inside. However, almost all whiteflies (99.4 %) were captured with the ICW. These results indicate that the insect-capturing function is effective to complement a failure to repel. A greenhouse assay was conducted in the screen-attached and non-screened parts in which a greenhouse was divided with a partition. During the 3-month operation, the screen was durable and functional for excluding pests, and better air ventilation changed the climate conditions in the greenhouse. Thus, the present study demonstrated that our electric field screen can provide an airy condition for tomatoes in a window-open greenhouse and successfully exclude whiteflies using dual screen functions.