Fatty acid homeostasis in honey bees (Apis mellifera) fed commercial diet supplements

Honey bees obtain lipids from pollen or commercial supplements. These supplements do not fully support colony health. We tested the hypothesis that supplements are deficient because they lack essential fatty acids (EFAs). The five supplements we tested had low linolenic (⍵3) acid and were unbalanced (⍵6:⍵3 > 6) compared to natural pollen. We selected two of these supplements for further study because they had different levels of individual EFAs and different ⍵6:⍵3 ratios. Bees from hives fed these different supplements had equivalent tissue EFA levels. In choice assays, hives fed these different supplements were presented with flours with various absolute and relative levels of EFAs. We saw no difference in foraging preference. Rather, all hives preferred flours with small grain size and high protein to lipid ratios. We conclude that bees balance their internal EFAs and that differential colony nutrition does not affect foraging preference. The data also argue for more linolenic (⍵3) acid in commercial supplements.

Elevated Temperature May Affect Nectar Microbes, Nectar Sugars, and Bumble Bee Foraging Preference

Floral nectar, an important resource for pollinators, is inhabited by microbes such as yeasts and bacteria, which have been shown to influence pollinator preference. Dynamic and complex plant-pollinator-microbe interactions are likely to be affected by a rapidly changing climate, as each player has their own optimal growth temperatures and phenological responses to environmental triggers, such as temperature. To understand how warming due to climate change is influencing nectar microbial communities, we incubated a natural nectar microbial community at different temperatures and assessed the subsequent nectar chemistry and preference of the common eastern bumble bee, Bombus impatiens. The microbial community in floral nectar is often species-poor, and the cultured Brassica rapa nectar community was dominated by the bacterium Fructobacillus. Temperature increased the abundance of bacteria in the warmer treatment. Bumble bees preferred nectar inoculated with microbes, but only at the lower, ambient temperature. Warming therefore induced an increase in bacterial abundance which altered nectar sugars and led to significant differences in pollinator preference.

Bombus (Megabombus) consobrinus Dahlbom, 1832 in the European North of Russia: its distribution and foraging preference

The focus of this study is to summarize the data on the distribution and foraging preference of Bombus (Megabombus) consobrinus Dahlbom, 1832 in the European North of Russia. The range of B. consobrinus in this region mostly repeats the disjunctions of the range of Aconitum septentrionale that is also known in Scandinavia. In other regions of Northern Eurasia, the close relationship of B. consobrinus with Aconitum is not obvious. This bumblebee species may be regarded as oligolectic in Northern Europe and the European North of Russia. We assume the presence of a coadaptive relationship of this bumblebee species with A. septentrionale in this region that presumably have been caused by the complex history of B. consobrinus in the European North.

Pollen Source Affects Development and Behavioral Preferences in Honey Bees

With the availability of various plants in bloom simultaneously, honey bees prefer to collect some pollen types over others. To better understand pollen’s role as a reward for workers, we compared the digestibility and nutritional value of two pollen diets, namely, pear (Pyrus bretschneideri Rehd.) and apricot (Armeniaca sibirica L.). We investigated the visits, pollen consumption, and pollen extraction efficiency of caged Apis mellifera workers. Newly emerged workers were reared, and the effects of two pollen diets on their physiological status (the development of hypopharyngeal glands and ovaries) were compared. The choice-test experiments indicated a significant preference of A. mellifera workers for apricot pollen diets over pear pollen diets (number of bees landing, 29.5 ± 8.11 and 9.25 ± 5.10, p < 0.001 and pollen consumption, 0.052 ± 0.026 g/day and 0.033 ± 0.013 g/day, p < 0.05). Both pollen diets had comparable extraction efficiencies (67.63% for pear pollen and 67.73% for apricot pollen). Caged workers fed different pollen diets also exhibited similar ovarian development (p > 0.05). However, workers fed apricot pollen had significantly larger hypopharyngeal glands than those fed pear pollen (p < 0.001). Our results indicated that the benefits conferred to honey bees by different pollen diets may influence their foraging preference.

Learned valuation during forage decision-making in cuttlefish

Decision-making, when humans and other animals choose between two options, is not always based on the absolute values of the options but can also depend on their relative values. The present study examines whether decision-making by cuttlefish is dependent on relative values learned from previous experience. Cuttlefish preferred a larger quantity when making a choice between one or two shrimps (1 versus 2) during a two-alternative forced choice. However, after cuttlefish were primed under conditions where they were given a small reward for choosing one shrimp in a no shrimp versus one shrimp test (0 versus 1) six times in a row, they chose one shrimp significantly more frequently in the 1 versus 2 test. This reversed preference for a smaller quantity was not due to satiation at the time of decision-making, as cuttlefish fed a small shrimp six times without any choice test prior to the experiment still preferred two shrimps significantly more often in a subsequent 1 versus 2 test. This suggests that the preference of one shrimp in the quantity comparison test occurs via a process of learned valuation. Foraging preference in cuttlefish thus depends on the relative value of previous prey choices.