Among the pollinator insects, honeybees (Apis mellifera) largely contribute to the pollination of the vast majority of crops, playing a key role in global food production, environmental balance, and the continuation of plant species. Because of climate changes, habitat destruction, pesticides, and nutrition deficits, honeybee populations are diminishing throughout the world, leading to serious ecological and economical concerns. Many different methods have been proposed over the years to boost honeybees’ resistance to external factors including the administration of natural substances like resveratrol [1], spirulina [2], vitamin C [3], and caffeine [4] together with various dietary additives such as soybean meal and pollen substitutes.
Evidence shows that these kinds of supplementations are capable of improving the overall well-being of the bees, stimulating the animal proteolytic (breakdown of proteins into amino acids or polypeptides) system, and the activity of antioxidant enzymes that offset aging and extend longevity. [1]
The use of hemp extracts appears interesting in this context, because of the valuable impact of phytocannabinoids on the central nervous system, their antioxidant activity, and their potential therapeutic use. The effects of hemp extract administration on honeybees were recently investigated to face the phenomenon of colony collapse disease (CCD). [5]
The activity of the enzymatic biomarkers accounting for CCD resistance and the metabolic compound concentrations (glucose and urea) in the hemolymph (insect blood) of adult workers bees were measured. The results highlighted the great immunostimulating effects of hemp extracts.
The study control group was fed ad libitum (as often as desired) with a mixture of sugar and water-glycerine solution and compared with two experimental groups differing for hemp extract administration method. The first group was fed a pure sugar syrup and cotton strips soaked with 3 ml of hemp extract (0.25 g of hemp paste extract + water-glycerine solution) were put into the cage, and the second group was given a mixture of sugar syrup and hemp extract ad libitum (4.38 g of pure hemp paste extract + 500 ml of water-glycerine solution).
The hemolymph of worker bees at age 2 and 7 days was collected and analysed for various biochemical indicators. The basic components of metabolism including glucose and urea concentration were analysed to provide information about the hemp extract effect on metabolic changes for sugar and proteins, respectively.
Moreover, the proteolytic system composed by proteases and their inhibitors was monitored because of their role in pathogen inactivation and inhibition. Hemp extract provided more energy than the food consumed by the control group because of the lipophilic nature of cannabidiol and other cannabinoids. The high penetration rate in the intracellular environment led to longer lasting sugar reserves for the body due to fat-induced, slower sugar metabolism.
The reduced consumption of hemp-enriched syrup was a positive sign because bees tend to eat more when they have infections. The increase in urea concentrations of the hemp extract-treated groups is a sign of the increased uptake of proteins and lipids in the diet. Depending on the administration method, hemp extract can act at different levels to boost the honeybees immune system. While hemp-extract on cotton strips helped with sealing the first immune barriers, limiting the penetration of large parasites, hemp extract mixed with sugar syrup strengthened the bees internal immune systems against easily penetrating pathogens, virusesm and microorganisms such as bacteria and fungi.
References:
[1] Rascón B, Hubbard BP, Sinclair DA, Amdam GV. The lifespan extension effects of resveratrol are conserved in the honey bee and may be driven by a mechanism related to caloric restriction. Aging (Albany NY). 2012;4(7):499-508. [journal impact factor = 5.682; times cited = 95]
[2] Ricigliano VA, Simone-Finstrom M. Nutritional and prebiotic efficacy of the microalga Arthrospira platensis (spirulina) in honey bees. Apidologie. 2020;51:898–910. [journal impact factor = 2.124; times cited = 7]
[3] Farjan M, Łopieńska-Biernat E, Lipiński Z, Dmitryjuk M, Żółtowska K. Supplementing with vitamin C the diet of honeybees (Apis mellifera carnica) parasitized with Varroa destructor: effects on antioxidative status. Parasitology. 2014;141(6):770-776. [journal impact factor = 3.234; times cited = 14]
[4] Strachecka A, Krauze M, Olszewski K, et al. Unexpectedly strong effect of caffeine on the vitality of western honeybees (Apis mellifera). Biochemistry (Mosc). 2014;79(11):1192-1201. [journal impact factor = 2.487; times cited = 30]
[5] Skowronek P, Wójcik Ł, Strachecka A. Cannabis extract has a positive–immunostimulating effect through proteolytic system and metabolic compounds of honey bee (Apis mellifera) workers. Animals. 2021; 11(8):2190. [journal impact factor = 1.654; times cited = 0]
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