Chemical insecticides demonstrate potent, immediate effects by specifically targeting the nervous, respiratory, or endocrine systems of the intended pest. However, repeated use of chemical insecticides is known to increase pest resistance, and the impact on non-target organisms and human health due to overuse cannot be ignored. Therefore, chemical insecticides are considered to have high environmental impact as a pest control method. In line with the global trend toward reducing chemical insecticides, Japan's agricultural sector has set a goal of reducing the use of chemical insecticides by 50 percent (risk-adjusted) by 2050. Consequently, the combined use of physical insecticides is being promoted. These have a limited impact on non-target organisms and are less likely to develop resistance because they block vital functions, such as respiration, that are essential for survival. While various physical insecticides exist, representative examples include machine oil emulsions, vegetable oils, and silicone oils. They work by physically blocking the insect's respiratory organs, called "spiracles" (spiracle occlusion), causing suffocation. However, the shift away from chemical insecticides has been slow due to the lower efficacy, shorter duration of effect, and slower onset of action of physical insecticides.

Isoparaffin is highly safe for humans and is already widely used in cosmetics, food additives, and food packaging. Its insecticidal effect through spiracles of occlusion has been known for over 100 years. Its insecticidal effect is limited and does not match that of chemical insecticides, which has led to its limited use. However, its high safety for non-target organisms, including humans, has brought renewed attention to it in recent years.

In collaboration with E-Tech Co., Ltd. (hereinafter referred to as "E-Tech"), the National Institute of Advanced Industrial Science and Technology (AIST) discovered that the insect repellent effect of isoparaffin is enhanced by mixing it with ozone, which is widely used for sterilization and other purposes.

While chemical insecticides demonstrate potent, immediate effects against target pests, they impose significant environmental burdens, including impacts on non-target organisms and humans. Additionally, frequent use can result in pests developing resistance, thereby restricting their use. Consequently, efforts are underway to combine chemical insecticides with physical insecticides that block the spiracles causing suffocation. However, physical insecticides, such as spiracular blockers, have drawbacks, including low immediate effectiveness, which makes the shift away from chemical insecticides difficult.

The newly developed technology improves the speed of effect and insecticidal efficacy of isoparaffin, a physical insecticide that previously served only limited purposes. Spray tests against public health pests revealed that a mixture of isoparaffin and ozone demonstrated higher insecticidal efficacy than isoparaffin alone. The time to suffocation death was shortened by up to approximately seven times. Isoparaffin have low environmental impacts and are used in many cosmetics and food products. This technology is expected to be applicable in the future for low-environmental-impact control of public health pests like mosquitoes and cockroaches, as well as agricultural pests such as stink bugs.

Journal：Scientific Reports
Title of paper： Enhanced insecticidal activity of isoparaffin by ozone as an adjuvant
Authors：H iroyuki Morimura, Hiroshi Shibata, Antoine-Olivier Lirette, Eiichi Yoshida, Yoshitomo Kikuchi
DOI：10.1038/s41598-025-20317-x