Medicinal plant essential oils as promising Anti-Varroa agents: Oxidative/nitrosative screens

Abstract

Melissa officinalis L., Quercus infectoria G. Oliviera, and Ceratonia siliqua L. are medicinal plants that have been used in different ethno-medical systems especially in the Iranian Traditional Medicine for the treatment of several diseases. Their several biological activities were well-documented, however, their anti-Varroa activities are unknown. Varroa destructor, the most important ectoparasite of Apis mellifera, threatens the honey bee populations all over the world so the search for novel control methods is an essential task for researchers. In this study, various concentrations (5, 10, 15, 20, and 25 μL/l air) of Quercus infectoria, Melissa officinalis, and Ceratonia siliqua essential oils at various exposure times (5, 10, 15, 20, and 25 h) were evaluated for their anti-Varroa activity. After exposure, mortality rate and oxidative/nitrosative stress biomarkers including superoxide dismutase [SOD], catalase [CAT], glutathione peroxidase [GSH-Px], protein carbonylation [PCO], malondialdehyde [MDA], total antioxidant status [TAS], nitric oxide contents [NO] in V. destructor were measured. The obtained results indicated that mite mortality was increased in parallel with increase in essential oils concentration and exposure time. The concentrations of 15, 20 and 25 μL/l air of all essential oils resulted in the induction of oxidative/nitrosative stress (decreased SOD, GST, CAT and GSH-Px, and increased MDA, PCO and NO), and mortality of V. destructor compared to the control. These essential oils did not cause a large amount of mortality in A. mellifera compared to the control group. Also, GC/MS analysis of the oils showed that carvacrol (24.97%), γ –Terpinene (20.68%) in M. officinalis oil, β-pinene oxide (21.09), β-pinene (14.31%) in Q. infectoria, Nonadecane (23.34%), 1,2-Benzenedicarboxylic acid, dibutyl ester (15.95%) in C. siliqua oil were the major chemical constituents. In conclusion, our experiment indicated that these essential oils could be a great agent of choice to manage V. destructor.