Biologically Active Extracts from Different Medicinal Plants Tested as Potential Additives against Bee Pathogens

Abstract

Honey bees (Apis mellifera) perform pollination service for many agricultural crops and contribute to the global economy in agriculture and bee products. However, honey bee health is an ongoing concern, as illustrated by persistent local population decline, caused by some severe bee diseases (e.g., nosemosis, AFB, EFB, chalkbrood). Three natural recipes are in development based on the bioactive compounds of different plants extract (Agastache foeniculum, Artemisia absinthium, Evernia prunastri, Humulus lupulus, Laurus nobilis, Origanum vulgare and Vaccinium myrtillus), characterised by HPLC-PDA. The antimicrobial activity of these recipes was tested in vitro against Paenibacillus larvae, Paenibacillus alvei, Brevibacillus laterosporus, Enterococcus faecalis, Ascosphaera apis and in vivo against Nosema ceranae. A mix of 20% blueberry, 40% absinthium, 10% oakmoss, 10% oregano, 10% Brewers Gold hops, 5% bay laurel and 5% anise hyssop extract showed the strongest antibacterial and antifungal activity. Combing several highly active plant extracts might be an alternative treatment against bee-disease-associated parasites and pathogens, in particular to replace synthetic antibiotics.

Agastache Species: A Comprehensive Review on Phytochemical Composition and Therapeutic Properties

“…Total polyphenolic content (TPC) was 485.08 mg gallic acid equivalents (GAE)/g for the methanolic extract and 403.91 mg GAE/g for the ethanolic extract [ 26 ]. These results are higher than those reported by others, who reported a TPC of 1.14 mg hydroquinone equivalents/g for the aqueous extract [ 36 ] and 2.88 mg GAE/g for the ethanolic extract [ 25 ]. However, differences regarding the extraction method, part of the plant used, and origin could lead to variations in results.…”

“…The essential oil was effective against DPPH radicals, inhibiting 77.88% of DPPH radicals at a concentration of 10 μL/mL [ 68 ]. A. foeniculum extract showed DPPH radical scavenging activity, cupric-reducing antioxidant capacity, and ABTS radical scavenging activity [ 25 , 27 , 37 ]. The antioxidant activity measured by the ABTS assay was 67.3 ± 1.9 µmol TE/g (TE = Trolox equivalents) [ 37 ].…”

Proteasome Inhibition Is an Effective Treatment Strategy for Microsporidia Infection in Honey Bees

“…Thus, efforts to find new treatment strategies are critical to protect honey bees from this parasite [ 16 , 19 ]. Many promising alternatives strategies for control of N. ceranae infection have now been pursued, including important studies exploring other small molecules, RNAi, probiotics, and various natural compounds ([ 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ] and work prior to 2020 reviewed in [ 30 ]). Eukaryotic pathogens can be challenging to combat using chemical antimicrobials because of the phylogenetic closeness with their hosts, and microsporidia are no exception.…”

Recent Advances in the Biocontrol of Nosemosis in Honey Bees (Apis mellifera L.)

“…Pașca et al [ 98 ] reported that integrating the honey bee diet with different plant extracts ( Agastache foeniculum , Artemisia absinthium , Evernia prunastri , Humulus lupulus , Laurus nobilis , Origanum vulgare , and Vaccinium myrtillus ) decreased the number of Nosema spores in a similar way to the commercial product Proitofil. The authors hypothesize that the mechanism of action is attributable to the bioactive compounds, such as phenolic acids and flavonoids contained in these extracts.…”