Search

Varroa destructor is the most important ectoparasitic mite of honey bees that has a negative impact on bee health and honey production. The control programs are mainly based on the use of synthetic acaricides that are often administered indiscriminately. All this has led to drug resistance that now represent a great concern for honey bee farming. The research for alternative products/methods for mites’ control is now mandatory. The aim of this study was to test whether Citrus spp. essential oils could diminish the growth of the V. destructor mite. In Calabria (southern Italy), plants of the Citrus genus are very common and grow both spontaneously and cultured. The essential oils used in this study were extracted from bergamot (Citrus bergamia), grapefruit (Citrus paradisi), lemon (Citrus limon), orange (Citrus sinensis), and mandarin (Citrus reticulata) by hydrodistillation. Every EO was in vitro tested against V. destructor. Each experimental replicate was performed using 35 viable adult female mites (5 for each EO) collected the same day from the same apiary and included negative controls (5 individuals exposed to acetone only) and positive controls (5 individuals exposed to Amitraz diluted in acetone). The essential oils (Eos) were diluted (0.5 mg/mL, 1 mg/mL, and 2 mg/mL) in HPLC grade acetone to obtain the working solution to be tested (50 µL/tube). Mite mortality was manually assessed after 1 h exposure under controlled conditions. The essential oils that showed the best effectiveness at 0.5 mg/mL were bergamot, which neutralized (dead + inactivated) 80% (p ≤ 0.001) of the parasites, grapefruit, which neutralized 70% (p ≤ 0.001), and lemon, which neutralized 69% of them. Interestingly, the positive control (Amitraz) at the same concentration neutralized 60% of the parasites. These results demonstrate that Calabrian bergamot, grapefruit, and lemon Eos consistently reduced V. destructor viability and open the possibility for their utilization to control this parasite in honey bee farming.

The potential role of plants and their metabolites has been recently considered in the search for new well-tolerated anti-arthritic and anti-obesity drugs. This study was designed to assess the potential effectiveness of the methanolic extracts from four wild edible species from Southern Italy, Asparagus officinalis L., Bellis perennis L., Daucus carota L. and Sambucus nigra L. All these plants have a history as anti-rheumatic or anti-arthritic remedies. The chemical constituents were identified through GC–MS and HPTLC analyses and the in vitro antioxidant activity was determined by means of DPPH, ABTS, FRAP-Ferrozine and β-carotene bleaching tests. To assess the anti-inflammatory and anti-arthritic potentials, the capacity to inhibit nitric oxide production in murine macrophage RAW 264.7 cells and protein denaturation was measured. The anti-obesity potential was determined by evaluating the ability of the sample to inhibit pancreatic lipase, a key enzyme for dietary fats absorption. The raw extract of D. carota showed the best inhibitory activity on NO production (IC50 = 45.1 ± 1.0 μg/mL), followed by B. perennis and A. officinalis (IC50 equal to 193.1 ± 3.2 μg/mL and 506.3 ± 5.1 μg/mL, respectively). D. carota induced also inhibitory effects against the heat-induced denaturation of bovine serum albumin (IC50 = 878.7 ± 19.09 μg/mL) and the best lipase inhibitory potential (IC50 = 1.63 ± 0.07 mg/mL). Our findings suggest that this species could be a potential effective therapeutic agent to treat inflammation and arthritis, supporting the traditional popular use of this plant.