Amino acid and carbohydrate tradeoffs by honey bee nectar foragers and their implications for plant–pollinator interactions

Abstract

Honey bees are important pollinators, requiring floral pollen and nectar for nutrition. Nectar is rich in sugars, but contains additional nutrients, including amino acids (AAs). We tested the preferences of free-flying foragers between 20 AAs at 0.1% w/w in sucrose solutions in an artificial meadow. We found consistent preferences amongst AAs, with essential AAs preferred over nonessential AAs. The preference of foragers correlated negatively with AA induced deviations in pH values, as compared to the control. Next, we quantified tradeoffs between attractive and deterrent AAs at the expense of carbohydrates in nectar. Bees were attracted by phenylalanine, willing to give up 84units sucrose for 1unit AA. They were deterred by glycine, and adding 100 or more units of sucrose could resolve to offset 1unit AA. In addition, we tested physiological effects of AA nutrition on forager homing performance. In a no-choice context, caged bees showed indifference to 0.1% proline, leucine, glycine or phenylalanine in sucrose solutions. Furthermore, flight tests gave no indication that AA nutrition affected flight capacity directly. In contrast, low carbohydrate nutrition reduced the performance of bees, with important methodological implications for homing studies that evaluate the effect of substances that may affect imbibition of sugar solution. In conclusion, low AA concentrations in nectar relative to pollen suggest a limited role in bee nutrition. Most of the 20 AAs evoked a neutral to a mild deterrent response in bees, thus it seems unlikely that bees respond to AAs in nectar as a cue to assess nutritional quality. Nonetheless, free choice behavior of foraging bees is influenced, for instance by phenylalanine and glycine. Thus, AAs in nectar may affect plant-pollinator interactions and thereby exhibit a selective pressure on the flora in the honey bee habitat.

Inter-Individual Nectar Chemistry Changes of Field Scabious, Knautia arvensis

“…Consumers of K. arvensis nectar will thus likely over-eat histidine if they aim to obtain sufficient amounts of the other amino acids (or a balanced C:AA ratio), with unknown consequences for their health or behavior. However, histidine may act as a repellent to honeybees as shown by Hendriksma et al [67], where nectar with histidine was less frequently consumed than nectar with glycine and cysteine.…”

“…As the competitiveness of a specific plant species can differ with the surrounding plant community [63,64], it is possible that K. arvensis experienced different, and community-dependent, levels of competition at different plots, which may have indirectly affected its nectar chemistry. In interaction with subtle, potentially also plant-community mediated, differences in soil quality (i.e., concentration and composition of soil nutrients, microbial communities), such community-dependent competition may (at least partly) explain the considerable variation in nectar chemistry both within and between plant communities [58,[65][66][67]. Community-dependent competition can also be caused by different intensities of wind-pollinated plant species [65].…”

“…The observed variation in nectar chemistry may in turn have had strong effects on flower visitors. For example, honeybees typically prefer sugar solutions with essential amino acids over sugar solutions with non-essential amino acids [69], but can be deterred by specific amino acids (e.g., alanine [68] or glycine [67]), while other amino acids (e.g., isoleucine) appear to act as a feeding stimulant and increase nectar consumption [70]. Differences in the concentration or proportion of specific amino acids can consequently attract or deter specific flower visitors and differences in amino acid proportions and ratios may thus structure visitation patterns.…”

Systems analyses of key metabolic modules of floral and extrafloral nectaries of cotton

“…We also identified GABA as a non-proteinaceous amino acid unique to floral nectar. Based on the fact that phenylalanine and GABA are known to elicit a strong phagostimulatory response in bees, the presence of these floral nectar-specific amino acids may function to attract this pollinator (Hendriksma et al, 2014; Nepi, 2014; Petanidou et al, 2006). GABA may also confer health benefits for bees as GABA-enriched artificial nectar has been shown to increase the locomotion and survival time of bees (Bogo et al, 2019).…”

Çeşitli Karbonhidrat Kaynaklarının Balarılarında Fonksiyonel Nitelik, Koloni Popülasyonu, Yem Tüketimi İle Üretilen Bal Üzerine Etkisi

“…As much the produced material gets dense, the percentage of fermentation reduced. It helps to produce a stable honey with normal content [11] Fraudulent and adulterated honey production is a problem all over the world [12] . Above all, we do not know how to distinguish adulterated honeys taken from the colonies that were [12] .…”