Fumigant toxicity of essential oils of Citrus limon L., Citrus sinensis L. and Citrus aurantium L. peels on three important stored products pests

Annually a significant portion of agricultural products is destroyed by the stored products pests. The chemical pesticides are commonly used to control pests. The residual hazards of pesticides on the storage products as well as increase in the pest resistance necessitate the selection of safe and effective control methods. The plant compounds can be the subject of researches on the storage pests control with the low-risk methods. Therfore, this experiment was conducted to study the effects of peel essential oil from three Citrus spp. including Citrus limon L., C. sinensis L., and C. aurantium L. on the adults of Callosobruchus maculatus F., Sitophilus granarius L., and Tribolium confusum Duv. The probit analysis was performed after 24 and 48 hours to evaluate the effects of essential oils on the pests. After determining the LC50 and LC25, the combinations of C. limon LC25 + C. aurantium LC25, C. limon LC25 + C. sinensis LC25, and C. sinensis LC25 + C. aurantium LC25 were tested to evaluate the combined effects of essential oils. The treatments had three replications and each replicate was performed on ten two-days-old adult insects in a completely randomized design. Also, the essential oils were analyzed by GC/MS to evaluate their major constituents. The LC50 value (µl.l-1) of essential oils of C. limon, C. sinensis, and C. aurantium was 3.8, 2.65, and 3.11 after 24 hours and 2.48, 1.93, and 2.88 after 48 hours on the S. granaries adults, 0.23, 2.41, and 2.66 after 24 hours and 0.13, 1.38, and 2.35 after 48 hours on C. maculatus, and 5.33, 2.76, and 1.35 after 24 hours and 24.2, 2.49, and 0.89 after 48 hours on T. confusum, respectively. The study on the combined effects of essential oils showed that the C. limon LC25 + C. sinensis LC25 treatment was more effective than the effect of each essential oil alone on all three pests. According to the results of this study, the use of Citrus peel essential oil, especially C. limon, could be recommended in the production of bio-pesticides.