Soil Surface-Trapping of Tomato Leaf-Miner Flies Emerging from Underground Pupae with a Simple Electrostatic Cover of Seedbeds in a Greenhouse

SIMPLE SUMMARY: Frequent infestation caused by tomato leaf miner flies (Liriomyza sativae) is a serious problem in the pesticide-independent cultivation of greenhouse tomatoes. This problem is caused by the persistent settlement of the flies in the greenhouse through larval movement between the phylloplane and rhizosphere soil of the host plants. The present work was conducted to develop a new physical control method to disrupt this developmental relationship. A simple electrostatic cover (EC) was constructed to trap adult flies emerging from underground pupae. The EC consisted of insulated iron rods linked to a voltage generator, which supplied a negative charge to the insulated iron rods, and non-insulated iron rods linked to a grounded line. The electric field formed in the space between the negatively charged and grounded iron rods generated an attractive force that could trap the target insects entering the electric field. A practical assay to demonstrate the functionality of the EC in a greenhouse revealed that the EC was able to capture all adult flies emerging from pupae. The simple structure of the EC makes it easy to fabricate for farmers who wish to integrate it into their pest management strategy. Thus, the present work provides an experimental basis for an electric field-based method for the control of tomato leaf miner flies. ABSTRACT: In the present study, an electrostatic apparatus for trapping adult tomato leaf miner flies (Liriomyza sativae) emerging from underground pupae at the surface of a seedbed in an organic greenhouse was developed. The apparatus consisted of insulated iron rods arranged in parallel at set intervals and linked to a voltage generator, which supplied a negative charge to the rods, as well as non-insulated grounded iron rods with the same configuration. The two layers of insulated and non-insulated iron rods were arrayed in parallel to form a static electric field between the layers. The electric field created a strong attractive force capable of capturing flies that entered the field. In a greenhouse assay, the apparatus was placed horizontally above a seedbed in a greenhouse and surveyed for its ability to capture adult flies emerging from pupae that were introduced onto the seedbed beneath the apparatus. The results revealed that the apparatus effectively trapped all adult flies that emerged from the pupae and that it functioned stably while continuously operated during the entire period of the experiment. Thus, our novel apparatus is a promising tool for the physical control of adult tomato leaf miners in the insecticide-independent cultivation of greenhouse tomatoes.