A study to determine the effect of essential oils, used together with mixed packaging, on controlling stored-grain insects, was conducted in the laboratory. Plant essential oils are one of the materials that act like a contact-fumigant, offering the prospect for use in stored product protection. Plant essential oils must have the ability to repel the insects in order to prevent penetration to foodstuffs. The objective of the present study was to test the properties of Cinnamomum camphora and Syzygium aromaticum for preventing the penetration of pest insects, including: Sitotroga cerealella and Ephestia kuehniella 5th instar larvae to packaged cereals. Ten grams of wheat and flour as foodstuffs were placed inside Cellophane packages and hung vertically in the top of a container. The repellent essential oils were used in the interior surface of containers. Each container had punctures at different parts and the insects were released around the container to determine insect penetration and the effect of the repellents. The experiments were conducted at 26±1°C, 60±5% RH in dark conditions. The highest concentration was 1.5 µl of essential oil per 0.5 ml acetone. Four days after the initiation of the experiment the results showed S. aromaticum had more of a repellency effect than C. camphora on both pests that caused contamination deduction inside the packaged foodstuffs compared with the control. However, both the essential oils were effective as protectants of cereals but S. aromaticum was more effective. S. aromaticum caused the most repellency on E. kuehniella. The mean of repellency of all the concentrations was 81.4%. The results demonstrated the efficacy of these essential oils for use in organic food protection. C. camphora and S. aromaticum can prevent warehouse infestation of stored-product pests.

Essential oils as alternative synthetic pesticides for pest management of foodstuffs have recently received increased attention. Controlled and slow release formulations of essential oils are used to enhance their efficiency. Two volatile essential oils of Mentha piperita L. and Salvia officinalis L. were investigated for release rate and mortality percentage by fumigant toxicity against 1st instar larvae of Plodia interpunctella. Electrospinning was used to incorporate various concentrations of essential oils in nanofibers. The essential oils can be released from the nanofibers for long periods of time, from several days to several weeks. Poly(lactic acid) was used as a green polymer carrier and the essential oils were incorporated into the nanofibers (8-15v/v% PLA). Insecticidal bioassay revealed that oil-loaded nanofibers (NFOs) were more toxic than pure essential oils (PEOs) against tested larvae. The LC50 and LT50 of NFOs were 1.2 and 4 times, respectively, more than PEOs. Our results indicated that PEOs completely lost their insecticidal activity after 14 days, whereas at the same period, NFOs had an average of 93% mortality when applied against P. interpunctella. Therefore, it can be concluded that nanofibers improved the persistence of the oil. This study presents S. officinalis has more toxicity and M. piperita had more persistence for controlling the larvae of indian meal moth.

In the most recent decade, nanoscale materials have received much attention because of their applications in the field of toxicology and biopesticides. Mentha piperita L. and Salvia officinalis L., as green pesticides were incorporated into Poly Lactic Acid (PLA) solution about 14%wt which were successfully electrospun into mats with ∼58 nm fiber diameters. The contact toxicity of essential oils (EOs) was tested on first instar larvae of Plodia interpunctella after 72-h to evaluate the effect of PLA nanofibers loaded with the EOs versus the pure essential oils (PEO)s on the mortality of the larvae over one month. The comparison between LC50 of the formulated essential oils (NFO)s and PEOs showed a significant difference (p< 0.05). The NFOs showed higher contact toxicity than the PEOs to control this pest for a longer time with slow release efficiency. Moreover, M. piperita showed more toxicity than S. officinalis. The nanofibers cause surface tension. Therefore, it is evaluated that this formulation increases the contact toxicity efficiency of essential oils as green contact pesticide. The nanofibers cause surface tension. Therefore, it is inferred that this formulation increases the contact toxicity efficiency of essential oils as green contact pesticide.