[5-1130-P] Food Quality (5th)

[5-1130-P-16] Pest Control of Tetranychus urticae by Branched Fatty Acids

*Mai Nagano¹, Akitaka Teshima¹, Toshinari Koda², Hiroshi Morita¹ (1. The University of Kitakyushu(Japan), 2. Nissan Chemical corporation(Japan))

Keywords:Pesticide, Spider mite, Fatty acid

Spider mite is one of the pests that infest many crops. Pesticides to prevent spider mites are less effective drugs due to the development of drug resistance by spider mites. Thus, new drugs are needed. The control of indoor environmental pollutants by fatty acid was examined for the purpose of creating a new safer control agent. In the process, it became clear that isopalmitic acid, which is a hyperbranched fatty acid, shows high acaricidal activity against house dust mite. Therefore, we decided to investigate the pest control effect of isopalmitic acid on the spider mites. The sample used isopalmitic acid (isoC16). As test ticks, the black spider mite (Tetranychus urticae) was used. It was fed with pea leaves. An acaricidal test was conducted against the spider mite. Pea leaves cut to a size of 2 cm × 2 cm were placed on damp filter paper. Ten female adults of Tetranychus urticae were placed on it. The sample was sprayed to 20 mg/cm² using a spray. After 24 h, lethality determination was performed under a stereomicroscope. The repellent effect was tested. Pea leaves were prepared in the same manner as the acaricidal test. Half of the leaf pieces were treated with the sample. One half was treated with ion-exchanged water to which 0.01% Tween 80 was added. Ten female adults of Tetranychus urticae were placed at the center of each disc. Under a microscope, the number of adult females was determined after 24 h and the number of eggs was determined after 72 h. The sustainability was tested. Pea leaf pieces were sprayed with the sample as in the acaricidal test. Sample Inoculation Five female adults of Tetranychus urticae were inoculated on days 0, 1, 3 and 5 of sample inoculation. After 24 h, the lethality of adult females was determined under a microscope. As a result of the acaricidal test, it was found that when the concentration of isoC16 was 1%, the acaricidal effect was 50% or more. As a result of the repulsion test, no significant difference was observed in the population of the spider mite on the treated area and the non-treated area in isoC16. As a result of the sustainability test, isoC16 showed an adjusted mortality rate of 50% or less at 0-5 days after treatment. For this reason, it became clear that isoC16 is low in sustainability. The corrected mortality rate was less than 50% even after 0 days of sample processing. Therefore, it was shown that in order for isoC16 to exert its pest control effect, it is necessary for the drug to be in direct contact with Tetranychus urticae.