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 84 units sucrose for 1 unit AA. They were deterred by glycine, and adding 100 or more units of sucrose could resolve to offset 1 unit 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 phenylanaline 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.

Omega-3 deficiency impairs honey bee learning

“…As we gain knowledge of essential nutrients, such as eFAs and amino acids (22,69), we could optimally design nutritionally balanced agricultural landscapes. Of the many stressors contributing to bee colony failure, Perry et al (70) recently showed that supplying adequate feeding can best prevent vulnerable colonies from collapse.…”

Floral abundance and resource quality influence pollinator choice

“…The most documented resource offered to insects by plants as an attractant for pollination is nectar. Foraging insects are capable of learning nectar rewards gained from visited flowers (Pyke, ), preferring to forage on flowers with significantly more nectar (Heinrich, ; Wolff, ) and with greater sugar concentration (Hendriksma et al ., ). After testing for relationships between nectar and pollen resources and pollinator visitations, our results support this, as typically, we found that greater nectar resources had a positive effect on insect and bee visitation.…”

Nutritional Effect of Alpha-Linolenic Acid on Honey Bee Colony Development (Apis Mellifera L.)

“…For honey bees, protein is the most important macro-nutrient of pollen substitutes because it is largely used to feed developing larvae and young bees to provide the structural elements of muscles, glands, and other tissues (De Groot, 1953;Herbert and Shimanuki, 1978a;Afik et al, 2006). Information regarding the protein and amino acid requirements of honey bee colonies and individuals, is plentiful (De Groot, 1953;Barker and Lehner, 1972;Kim and Smith, 2000;Afik et al, 2006;Weiner et al, 2010;Hendriksma et al, 2014;Paoli et al, 2014), but data regarding lipid or fatty acid requirements are scarce. Nevertheless, lipids, among then fatty acids, play an important role in the honey bee diet (Loidl and Crailsheim, 2001;Manning et al, 2007).…”