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 from 15 wt% up to 33 wt%. Insecticidal bioassay revealed that oil-loaded nanofibers (NFOs) were more toxic than pure essential oils (PEOs) against tested larvae. The LC50 and LT 50 of NFOs were 0.7 and 4.5 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. In all tests of fumigant toxicity for determining LT50 and LC 50, M. piperita was the most effective on 1st instar larvae of P. interpunctella.
