ORIGINAL PAPER MA-chitosan nanogel loaded with Cuminum cyminum essential oil for efficient management of two stored product beetle pests Masumeh Ziaee • Saeid Moharramipour • Afshin Mohsenifar Received: 10 October 2013 / Accepted: 11 April 2014 Ó Springer-Verlag Berlin Heidelberg 2014 Abstract Natural essential oils have received increased attention as alternatives to synthetic pesticides for pest management of foodstuffs. Recently, microencapsulation and other controlled release techniques are used to increase insecticidal efficiency and persistence of essential oils with slow and controlled release. In this study, the possibility of improving the insecticidal activity of plant essential oils was investigated for effective management of two stored product beetle pests. Self-assembly technique was used to prepare nanogels of myristic acid-chitosan loaded by essential oil extracted from cumin, Cuminum cyminum L. Fumigant toxicity of C. cyminum oil and oil-loaded nano- gels (OLNs) were investigated at 4, 7, 10, 13, and 16 lL/L air against the granary weevil Sitophilus granarius L. and 8, 11, 14, 17, and 20 lL/L air for confused flour beetle Tribolium confusum Jacquelin du Val. Experiments were conducted at 27 ± 1 °C and 55 ± 5 % relative humidity in continuous darkness. Insecticidal bioassay revealed that OLNs were more toxic than C. cyminum oil against tested beetle pests. The persistence of the oil and OLNs was also evaluated against two tested species. Results indicated that C. cyminum oil completely lost its insecticidal activity after 12 days, whereas at the same period, the OLNs lost about 60 % of its activity when applied against S. granarius and 15% for T. confusum. Therefore, it could be concluded that encapsulation improved the persistence of the oil. Keywords Cuminum cyminum Á Fumigant toxicity Á Nanogel Á Persistence Á Storage pests Introduction During recent years, some plant essential oils have received increased attention as natural pesticides, and are considered among the most promising alternatives to residual insecti- cides. They have contact and fumigant activity against some economically important insect pests, stored-grain pests, and also pathogenic fungi (Isman 2000). Essential oils (EOs) are extracted from different parts of plants by steam distillation. They have a lot of advantages such as low mammalian toxicity, rapid degradation, local avail- ability, and they have been used traditionally in medicine, herbal beverages, pharmacy, and as natural flavorings (Li et al. 2010). However, their high cost of production, low vapor pressure, high volatility, low persistence, strong odor, low efficacy especially against large chewing insects and phytotoxicity limit their application to control pests (Isman 2006; Isman et al. 2010). In agricultural field, nanocapsules loaded with pesticides are prepared in order to protect the active ingredient from environmental adverse effects, increase their toxicity, and decrease applied con- centration (Abreu et al. 2012). Therefore, encapsulation of EOs could improve their stability and efficacy, overcome some of their limitations, and make their application more practical. Communicated by C. G. Athanassiou. M. Ziaee Á S. Moharramipour (&) Department of Entomology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran e-mail: moharami@modares.ac.ir M. Ziaee Department of Plant Protection, Faculty of Agriculture, Shahid Chamran University, Ahvaz, Iran A. Mohsenifar Research and Development Department of Nanozino, Tehran, Iran 123 J Pest Sci DOI 10.1007/s10340-014-0590-6