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

GIMÉNEZ MARTÍNEZ PABLO DARIAN; RAMOS FACUNDO; EGUARAS MARTIN; ALONSO-SALCES ROSA MARIA; MAGGI MATIAS; FUSELLI SANDRA

Congreso; Reunion Conjunta de Sociedades de Biociencias; 2017

Varroosis caused by Varroa destructor is considered the greatestdisease of the honeybee. Mite control is mainly based on theapplication of synthetic acaricides but its continuous use over timeleads to a selection pressure causing several foci of resistance andcontamination of bee products in the entire world. A range of essentialoils have been found to exhibit acaricide activity against V.destructor. The main objective of the present work was to evaluatethe acaricidal activity on V. destructor of the essential oil Cymbopogonnardus obtained from Argentina and India, as well as the activityof the major component of this oil, the Citronelal monoterpenoid.The LC50 of both essential oils and the compound was estimated byusing a full exposure method. Oils and component concentrationsbetween 0 (control) to 40 μl/ml were applied in the inner surface ofPetri dishes. Alcohol was used as solvent, after itsevaporation, 5adult worker bees and 5 mites were placed with a feeder containingwater and candy in each Petri dish. Capsules were incubated at30°C and 70% RH. The mortality of mites and bees at 24, 48 and72 hours was recorded for each treatment. By probit analysis theLC50 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 treatmentat each observation. The essential oil from India and the Citronelalcompound were the most toxic against mites and bees (LC50 2.38μl/ml and 10μl/ml) and promising acaricide effect on mites (4.26 ul/ml). These resultsshow that the essential oil of C. nardus from Argentina