Acaricidal activity on Varroa destructor of two essential oils of Cymbopogon nardus from two different countries and their Citronellal monoterpenoid

GIMENEZ MARTINEZ PABLO; RAMOS FACUNDO; EGUARAS MARTIN; MAGGI MATIAS

Buenos Aires

Congreso; Reunion Conjunta de Sociedades de Biociencias; 2017

Varroosis caused by Varroa destructor is considered the greatest disease of the honeybee. Mite control is mainly based on the application of synthetic acaricides but its continuous use over time leads to a selection pressure causing several foci of resistance and contamination of bee products in the entire world. A range of essential oils have been found to exhibit acaricide activity against V. destructor. The main objective of the present work was to evaluate the acaricidal activity on V. destructor of the essential oil Cymbopogon nardus obtained from Argentina and India, as well as the activity of the major component of this oil, the Citronelal monoterpenoid. The LC50 of both essential oils and the compound was estimated by using a full exposure method. Oils and component concentrations between 0 (control) to 40 μl/ml were applied in the inner surface of Petri dishes. Alcohol was used as solvent, after itsevaporation, 5 adult worker bees and 5 mites were placed with a feeder containing water and candy in each Petri dish. Capsules were incubated at 30°C and 70% RH. The mortality of mites and bees at 24, 48 and 72 hours was recorded for each treatment. By probit analysis the LC50 was estimated for each essential oil and citronelal compound, expressed in μl of compound/ml. A selectivity ratio, calculated as A. mellifera LC50/V. destructor LC50, was determined for each treatment at each observation. The essential oil from India and the Citronelal compound were the most toxic against mites and bees (LC50 2.38 μl/ml and 10µl/ml) and promising acaricide effect on mites (4.26 ul/ml). These results show that the essential oil of C. nardus from Argentina could be a succesfull alternative in the control of Varroosis.