Nutrition affects survival in African honeybees exposed to interacting stressors

Abstract

Summary1. Nutrition plays an important role in physiological stress resistance and by adjusting their intake of key nutrients, such as protein and carbohydrate, many animals can better resist stress. 2. Poor nutrition may contribute to the widespread and on-going declines of honeybee populations by increasing their vulnerability to abiotic (e.g. pesticides) and biotic (e.g. diseases) stressors. However, we do not know how nutrition affects stress resistance in social insects such as honeybees. 3. Here, we examined how exposure to the toxic secondary metabolite nicotine, a neurotoxin that shares structural similarities with the neonicotinoid pesticides, and low temperatures affected nutrient regulation in honeybees using the Geometric Framework of nutrition. 4. Groups of queenless, newly emerged worker bees were given diets containing specific ratios of protein and carbohydrate to determine, first, how toxin exposure and ambient temperature affected their nutrient intake and, secondly, how nutrition affected survival under stress. 5. We find that low temperatures and nicotine interacted to reduce survival in African honeybees that ate low protein, high carbohydrate diets. However, bees fed a high protein diet were better able to survive insult with these interacting stressors. 6. Although protein conferred a survival benefit in honeybees exposed to these dual stressors, when allowed to self-select their diet, caged workers did not shift their intake towards a higher protein food to improve their survival under these stressful conditions. 7. We discuss the possible constraints on nutrient regulation in honeybees and the role that diet could play in their decline.

Antioxidant supplementation can reduce the survival costs of excess amino acid intake in honeybees

“…hypopharyngeal gland development - Crailsheim et al, 1992). Furthermore, this intake target contains more carbohydrate than that preferred by bees fed diets containing protein in the form of casein (between 1:6.5 P:C -1:12 P:C) (Altaye et al, 2010;Archer et al, 2014a). This is presumably because free amino acids provide a more readily accessible form of nitrogen that is absorbed more quickly and efficiently than proteins (Rønnestad et al, 2000).…”

“…A poor diet, due to land use changes reducing the availability and diversity of floral resources, may help drive these declines (Vanbergen and the Insect Pollinators Initiative, 2013). In keeping with this idea, nutrition is a key determinant of honeybee survival (Altaye et al, 2010;Archer et al, 2014a): African honeybees (Apis mellifera scutellata) fed high protein diets experience reduced survival and European honeybees (Apis mellifera) survive poorly when fed diets rich in essential amino acids (EAAs) (Paoli et al, 2014). To protect declining and threatened honeybee populations (Pirk et al, 2014) it is important that we better understand the association between diet and honeybee survival, and find ways of mitigating the costs of poor nutrition, especially in populations which are underrepresented in the literature (Archer et al, 2014b).…”

Influence of different pollen diets on the development of hypopharyngeal glands and size of acid gland sacs in caged honey bees (Apis mellifera)

“…The suitability of Feedbee® as pollen substitute is controversially discussed (De Jong et al 2009;Altaye et al 2010;Saffari et al 2010;Archer et al 2014). According to our experiments, it promotes HPG development better than a protein-free diet, similar to some naturally occurring monofloral pollen that poorly promotes development (Helianthus sp.…”

How to know which food is good for you: bumblebees use taste to discriminate between different concentrations of food differing in nutrient content

“…Because bees have a generally high metabolic activity and comparatively low energy stores, they are particularly prone to suffering from an imbalanced nutrient intake if nutrients are provided in excess or deficient amounts (Raubenheimer and Simpson, 1993). For instance, too much protein (DeGroot, 1953;Standifer et al, 1960;Herbert et al, 1977;Pirk et al, 2010) and specific amino acids (Simpson and Raubenheimer, 2009) can be detrimental, and honeybees have shorter life spans when fed a diet high in proteins Archer et al, 2014). In contrast, pollen of comparatively higher protein content was found to benefit larval growth and development (Herbert et al, 1977;Herbert, 1992;Tasei and Aupinel, 2008) and, up to a certain amount, to increase adult survival and immune functioning (Génissel et al, 2002;Brunner et al, 2014).…”

“…protein content). This would enable them to better regulate nutrient intake, which would be highly beneficial for their colonies, as well-nourished individuals can better withstand stressors like parasites, infections, insecticides and drought periods (Szymas and Jedruszuk, 2003;Brodschneider and Crailsheim, 2010;Archer et al, 2014;Kay et al, 2014).…”