Potential Use of Buddleja Thyrsoides for the Control and Prevention of American Foulbrood Disease in Honey Bees

Abstract

a b s t r a c t Paenibacillus larvae is the causative agent of american foulbrood (afb), a severe disease that affects the larvae of the honeybees. the use of plant extracts are considered to be an alternative way of controlling the disease. in this study, the in vitro antimicrobial activity of buddleja thyrsoides lam. against the Paenibacillus species, including P. larvae, was evaluated. in mueller-hinton broth, the minimal inhibitory concentration (miC) was assessed using the microdilution method. all Paenibacillus species were sensitive to the crude extract and the fractions of b. thyrsoides. the ethyl acetate (ea) fraction showed a better result with miC values of 1.68 -3.36 mg/ml, followed by butanolic (bU) (miC = 2.18 -6.54 mg/ml), dichloromethane (dCm) (7.40 -14.80 mg/ml), and crude extract (Ce) (7.51 -16.90 mg/ml). the toxic effect of the Ce and fractions of b. thyrsoides against bees were also evaluated using the spraying application method with the same concentrations of miCs. bee mortality was evident in treatment with dCm fractions only, while Ce, ea, and bU extracts showed no toxic effects after 15 days of observation. furthermore, phenolic acids, tannins, and flavonoids were identified and quantified by highperformance liquid chromatography (hPlC), and may be partially responsible for the antimicrobial properties observed. these results show, for the first time, that b. thyrsoides might be a natural alternative for the prevention/control of afb.

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

“…To our knowledge there are not many studies on the effectivity of alcoholic extracts of blueberries, absinthium, oakmoss, oregano, Brewers Gold hops, bay laurel and anise hyssop on bee pathogens [ 33 , 34 , 36 ]. Nevertheless, the results of the current study are in line with results of many other plants extracts, which are used against bee parasites and pathogens (nosemosis, AFB, EFB, chalkbrood), such as: Aristotelia chilensis, Gevuina avellana, Ugni molinae and propolis methanolic extracts [ 40 ] or Buddleja thyrsoides [ 58 ] and Scutia buxifolia [ 59 ]; furthermore, some studies use Humulus lupulus and Myrtus communis [ 60 ], Origanum vulgare and Rosmarinus officinalis [ 61 ] or Laurus nobilis [ 12 , 33 , 34 ]. However, others showed that bay laurel oil and phenolic extracts of berries had very low or no activity on Gram-positive bacteria [ 11 ].…”

Antimicrobial activity of plant extracts against the honeybee pathogens,Paenibacillus larvaeandAscosphaera apisand their topical toxicity toApis melliferaadults

“…Plant extracts such as Buddleja thyrsoides (Boligon et al . ), Humulus lupulus L., Myrtus communis L. (Flesar et al . ), Scutia buxifolia (Boligon et al .…”

“…Antibacterial activity of other plant species against P. larvae has been previously studied. Plant extracts such as Buddleja thyrsoides (Boligon et al 2014), Humulus lupulus L., Myrtus communis L. (Flesar et al 2010), Scutia buxifolia (Boligon et al 2013) and Laurus nobilis (Damiani et al 2014) showed inhibitory activity against P. larvae with MIC values of 7Á51-16Á90 mg ml À1 , 2-4 lg ml À1 , 2-8 lg ml À1 , 50 mg ml À1 and 208-416 lg ml À1 respectively. In addition, propolis (plant resins collected by bees) has shown efficacy in inhibiting American Foulbrood (Antunez et al 2008;Bastos et al 2008).…”

Antimicrobial, Cyto and Genotoxic Activities of Equisetum hyemale

“…After that, the remaining aqueous extract was partitioned with dichloromethane (DCM), ethyl acetate (EA) and n-butanol (NB), successively. 10…”

“…8,9 Their chemical structure is characterized by having a hydroxyl attached directly to an aromatic hydrocarbon group, and exhibit different biological effects, such as antitumor, antioxidant, anti-inflammatory, antiviral and antimicrobial activities. [10][11][12][13] Therefore, the phenyl compounds could be used as an alternative, to increase our therapeutic arsenal, because the disorderly use of antimicrobial drugs is contributing to the growth of micro-organisms that are resistant to treatments; namely, these strains are able to multiply in the presence of antimicrobial concentrations higher than the doses recommended for the treatment of the patient. [14][15][16] After the discovery of the first antimicrobial drugs, it was evident that bacteria possessed resistance mechanisms; however, this scenario was livened up with the frequent introduction of new antibiotics.…”