Turkestan Cockroaches Avoid Entering a Static Electric Field upon Perceiving an Attractive Force Applied to Antennae Inserted into the Field

SIMPLE SUMMARY: Electrostatic devices that generate a static electric field (S-EF) are used as barriers to repel insect pests because insects habitually avoid entering a S-EF. Understanding the avoidance mechanism would provide an experimental basis for developing electrostatic-based pest control methods. An apparatus generating a S-EF was constructed by placing a polyvinyl chloride-insulated iron plate (N-PIP) that was negatively charged using a voltage generator parallel to a grounded metal net (G-MN) that was positively polarised via electrostatic induction due to the negative charge of the N-PIP. The S-EF formed in the space between the N-PIP and G-MN, where the negative charge of the N-PIP generated a repulsive force to push electrons in the field toward the ground via the G-MN. A test insect (an adult Turkestan cockroach, Shelfordella lateralis Walker) released in the space surrounded by the apparatus inserted its antenna into the S-EF and reflexively moved backward. Free electrons were pushed out of the antenna tip toward the ground, and the antenna became positive. The positively polarised antenna was attracted to the N-PIP, and in response to this force, the insect pulled its antennae back reflexively and moved backward. This insect action was recognised as avoidance behaviour. ABSTRACT: This study analysed the mechanism of avoidance behaviour by adult Turkestan cockroaches (Shelfordella lateralis Walker) in response to a static electric field (S-EF) formed in the space between a negatively charged polyvinyl chloride-insulated iron plate (N-PIP) and a grounded metal net (G-MN). The negative surface charge supplied to the iron plate by a voltage generator caused the G-MN to polarise positively via electrostatic induction. In the S-EF, the negative charge of the N-PIP created a repulsive force that pushed free electrons in the field toward the ground via the G-MN. When insects released in the space surrounded by the S-EF inserted their antennae into the S-EF, they pulled them back reflexively and moved backward. The analysis indicated that an electric current flowed transiently toward the ground when an insect inserted its antennae into the S-EF. The insect became positively charged via this discharge and was attracted to the opposite pole (N-PIP). In response to this attractive force, the insect pulled its antennae back quickly. The positive electrification caused by the removal of free electrons from the antenna tip triggered the avoidance behaviour.