Controlling varroa mites infesting honeybees (Apis mellifera L.) Using some essential oils and amitraz under colony conditions

Varroosis is a disease of Apis mellifera L. caused by the mite Varroa destructor Anderson and Trueman. Essential oils and their chemical constituents offer a safe alternative to synthetic acaricides for the control of this mite in bee hives. The present study was conducted to evaluate anti-parasitic activity of essential oils from Thymus kotschyanus Bioss & Hohen., Mentha longifolia L., Eucalyptus camaldulensis Dehnh., and Ferula gummosa L. at concentrations of 1, 2.5, 4, and 5.5 µl/l air for 5 and 10 h. Findings indicated that mite mortality increased as oils concentration and exposure time increased. T. kotschyanus oil at 5.5 µl/l air caused a mite mortality rate of 54.4% and 84.43% after 5 and 10 h fumigation, respectively. At the same concentration and exposure time, the honey bee mortality was 0% and 7.2%, respectively. Application of M. longifolia and E. camaldulensis oils at 5.5 µl/l air resulted in 65.53% and 71.06% mortality in Varroa mites and 10.13% and 12% mortality in honey bees after 10 h exposure. Despite moderate acaricidal activity of F. gummosa oil against Varroa mite (49.69%), it was highly toxic to honey bee (30%). Also, GC/MS analysis of the oils showed that carvacrol (47.99%) and thymol (30.61%) in T. kotschyanus oil, piperitenone (36.86%), piperitenone oxide (27.53%),Cispiperitone epoxide (22.21%), and pulegone (8.38%) in M. longifoliaoil, 1,8-cineol (74.7%) and α-pinene (8.35%) in E. camaldulensis oil, and β-pinene (87.29%) in F. gummosa oil were the main chemical constituents. Collectively, our results led to a conclusion that T. kotschyanus, M. longifolia, and E. camaldulensis oils have enough potential to play an important role in integrated control programs of varroosis in apiaries.

Download Full-text

Effect of yeast and essential oil-enriched diets on critical determinants of health and immune function in Africanized Apis mellifera

PeerJ ◽

10.7717/peerj.12164 ◽

2021 ◽

Vol 9 ◽

pp. e12164

Author(s):

César Canché-Collí ◽

Humberto Estrella-Maldonado ◽

Luis A. Medina-Medina ◽

Humberto Moo-Valle ◽

Luz Maria Calvo-Irabien ◽

...

Keyword(s):

Apis Mellifera ◽

Food Intake ◽

Essential Oils ◽

Immune Function ◽

Honey Bees ◽

Fat Body ◽

Control Diet ◽

Starmerella Bombicola ◽

Expression Of Genes ◽

Brewers Yeast

Nutrition is vital for health and immune function in honey bees (Apis mellifera). The effect of diets enriched with bee-associated yeasts and essential oils of Mexican oregano (Lippia graveolens) was tested on survival, food intake, accumulated fat body tissue, and gene expression of vitellogenin (Vg), prophenoloxidase (proPO) and glucose oxidase (GOx) in newly emerged worker bees. The enriched diets were provided to bees under the premise that supplementation with yeasts or essential oils can enhance health variables and the expression of genes related to immune function in worker bees. Based on a standard pollen substitute, used as a control diet, enriched diets were formulated, five with added bee-associated yeasts (Starmerella bombicola, Starmerella etchellsii, Starmerella bombicola 2, Zygosaccharomyces mellis, and the brewers’ yeast Saccharomyces cerevisiae) and three with added essential oils from L. graveolens (carvacrol, thymol, and sesquiterpenes). Groups of bees were fed one of the diets for 9 or 12 days. Survival probability was similar in the yeast and essential oils treatments in relation to the control, but median survival was lower in the carvacrol and sesquiterpenes treatments. Food intake was higher in all the yeast treatments than in the control. Fat body percentage in individual bees was slightly lower in all treatments than in the control, with significant decreases in the thymol and carvacrol treatments. Expression of the genes Vg, proPO, and GOx was minimally affected by the yeast treatments but was adversely affected by the carvacrol and thymol treatments.

Download Full-text

Evaluating the Efficacy of 30 Different Essential Oils against Varroa destructor and Honey Bee Workers (Apis mellifera)

Insects ◽

10.3390/insects12111045 ◽

2021 ◽

Vol 12 (11) ◽

pp. 1045

Author(s):

Marian Hýbl ◽

Andrea Bohatá ◽

Iva Rádsetoulalová ◽

Marek Kopecký ◽

Irena Hoštičková ◽

...

Keyword(s):

Essential Oils ◽

Honey Bees ◽

Varroa Destructor ◽

Mortality Rates ◽

Selectivity Ratio ◽

Varroa Mites ◽

Main Components ◽

Honey Bee Workers ◽

Over Time ◽

Better Than

Essential oils and their components are generally known for their acaricidal effects and are used as an alternative to control the population of the Varroa destructor instead of synthetic acaricides. However, for many essential oils, the exact acaricidal effect against Varroa mites, as well as the effect against honey bees, is not known. In this study, 30 different essential oils were screened by using a glass-vial residual bioassay. Essential oils showing varroacidal efficacy > 70% were tested by the complete exposure assay. A total of five bees and five mites were placed in the Petri dishes in five replications for each concentration of essential oil. Mite and bee mortality rates were assessed after 4, 24, 48, and 72 h. The LC50 values and selectivity ratio (SR) were calculated. For essential oils with the best selectivity ratio, their main components were detected and quantified by GC-MS/MS. The results suggest that the most suitable oils are peppermint and manuka (SR > 9), followed by oregano, litsea (SR > 5), carrot, and cinnamon (SR > 4). Additionally, these oils showed a trend of the increased value of selective ratio over time. All these oils seem to be better than thymol (SR < 3.2), which is commonly used in beekeeping practice. However, the possible use of these essential oils has yet to be verified in beekeeping practice.

Download Full-text