The aims of this study were to develop insect-proof halloysite nanotubes (HNTs) and apply the HNTs to a low-density polyethylene (LDPE) film that will prevent Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae), commonly known as Indian mealmoth, from infesting the food. Clove bud oil (CO), an insect repellent, was encapsulated into HNTs with polyethylenimine (PEI) to bring about controlled release of CO. Chemical composition and insecticidal effect of CO were examined. The Fourier transform infrared (FTIR) spectrum of encapsulated CO was confirmed. The surface charges of uncoated HNTs (HNTs/CO) and coated HNTs with PEI by the layer-by-layer (LBL) method (HNTs/CO/LBL) were determined to be -37.23 and 36.33 mV, respectively. HNTs/CO/LBL showed slow, controlled release of CO compared to HNTs/CO. After 30 d, the residual amounts of CO in HNTs/CO and HNTs/CO/LBL were estimated to be 13.43 and 28.66 mg/g, respectively. HNTs/CO/LBL showed the most sustainable repellent effect. HNTs applied to gravure printing ink solution did not affect mechanical, optical, or thermal properties of the developed film. Gravure-printed LDPE film containing HNTs/CO/LBL displayed the greatest preventive effect on insect penetration, indicating its potential for use as insect-resistant food packaging materials.

The objectives of this study were to develop insect-resistant adhesives and apply them to a cardboard packaging system for preventing Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) larvae infestation. Cinnamon essential oil (CO), an insecticide, was encapsulated with maltodextrin (CS/MD/CO), β-cyclodextrin (CS/β-CD/CO), and polyvinyl alcohol (CS/PVA/CO) in corn starch (CS) paste. This resulted in a sustained and gradual release of CO from the starchbased insect-proof adhesives. Penetration pathways of insects into corrugated cardboard boxes were investigated through the use of a screening test for infestation profiling. Microscopic images of encapsulated CO in an oil in water (O/W) emulsion were observed to confirm the morphology of the adhesives. Adhesion forces of CS, CS/CO, CS/MD/CO, CS/β-CD/CO,and CS/PVA/CO were determined to be 6.2 N,4.0 N,3.1 N,6.0 N,and 5.8 N,respectively.Consequently, significant decreases of adhesion force in the CS/CO and CS/MD/CO were found to be due to the presence of the surfactant (Span ® 80) and the low adhesive properties of MD. The duration of the insecticidal activities of the developed adhesives was evaluated by measuring their release rates for 14 days and repellent profiles up to 24 hr and 40 days. As a result, CS/β-CD/CO and CS/PVA/CO were found to have an inhibited rapid release and sustained repellent profiles. In conclusion, CS/β-CD/CO and CS/PVA/CO were determined to be suitable for encapsulation models and could be applied to industrial cardboard containers to prevent cases of insect invasion.

Previous study reported the development of insect‐proof halloysite nanotubes (HNTs) and food packaging; however, the duration of their insecticidal properties remains unclear. Here, we aimed to (1) demonstrate the duration of repellency of clove bud oil (CO) encapsulated by HNTs for more than 30 days, and (2) manufacture insect‐proof film containing HNTs for commercial use. Also, the release behavior of CO from insect‐resistant HNTs was evaluated and HNTs were applied to food packaging composed of polypropylene and low‐density polyethylene films to prevent Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) larva infestation. CO, a natural insecticide, was embedded with HNTs and polyethyleneimine (PEI) via vacuum pulling process to cause a slow and gradual release of CO. The sustained release profile of CO from CO‐containing HNTs with a PEI coating [(HNTs/CO/layer‐by‐layer (LBL)] was verified by gas chromatography analysis. The repellent activity of HNTs/CO/LBL was observed for up to 46 days, whereas CO film and HNTs/CO film exhibited no insecticidal activities during the test period. After 30‐day exposure, the HNTs/CO/LBL film exhibited a 7‐day extension in the penetration test. To evaluate the insecticidal properties of the insect‐proof film (HNTs/CO/LBL scale‐up film) manufactured in an industrial facility, the inhibitory effects of HNTs/CO/LBL scale‐up film on insect infestation was elucidated in both the segregation and combination tests. As a result, HNTs/CO/LBL alone or gravure‐printed film treated with HNTs/CO/LBL were capable of protecting food from insect infestation. Practical Application Halloysite nanotubes containing natural insect repellent were applied to industrial production of food packaging. Commercial cornflake cereal packaging using insect‐resistant film successfully inhibited pest infestation. Insect‐proof film produced at an industrial facility can be utilized to protect processed food from insect infestation.

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