Biology subjects
Publications and source records attributed to Wright, G. A..
Withdrawal StatementThe authors have withdrawn their manuscript because one of the listed authors had not provided approval of the authorship and submission prior to submission. Therefore, the authors do not wish this work to be cited as reference for the project. If you have any questions, please contact the corresponding author.
Learning cues such as tastes associated with palatable food is an important mechanism animals have for foraging optimally. Insects can use gustatory receptor neurons (GRNs) in their mouthparts to detect nutrients and toxins, but they also taste compounds using sensilla on peripheral organs such as their antennae. Bees are adept at learning to associate floral traits with the presence of nectar rewards, but few studies have examined how they incorporate gustatory information from their antennae with rewards. Here, we characterize the ability of adult worker bumblebees (Bombus terrestris) to taste sugar, salt, and bitter compounds using their antennae and then tested whether they could use this sensory information to associate it with food. We show that bumblebees have antennal GRNs sensitive to sugars, salts, and bitter compounds and that they can use surface chemistry differences detected by their periphery to learn about the presence or absence of flower rewards in a free-flight assay. Naive bumblebees showed no instinctual preferences toward or against any surface chemistry tested. Bumblebees performed best when sucrose surface cues were associated with sucrose reward, but they could learn to associate any cue with the presence or absence of sucrose solution. Interestingly, the bees found it more difficult to associate quinine surface chemistry with the presence of reward than its absence. These results indicate that bees have the potential to learn to associate another floral trait - chemicals on the surfaces of petals - with the quality of floral rewards. Summary statementBehavioural experiments and electrophysiological recordings show bumblebees can detect peripheral taste cues on surfaces of artificial flowers, including bitter toxins, and learn to use these to predict rewards.
Honeybees, the worlds most important crop pollinators, are increasingly facing pollen starvation arising from agricultural intensification and climate change. Frequent flowering dearth periods and high-density rearing conditions weaken colonies, often leading to their demise. Beekeepers provide colonies with pollen substitutes, but these feeds cannot sustain brood production because they lack essential sterols found in pollen. Here, we describe a technological breakthrough in honeybee nutrition with wide-reaching impacts on global food security. We first measured the quantity and proportion of sterols found in honeybee tissues. Using this information, we genetically engineered a strain of the oleaginous yeast, Yarrowia lipolytica, to produce a mixture of essential sterols for bees and incorporated it into an otherwise nutritionally complete diet. Colonies fed exclusively with this diet reared brood for significantly longer than those fed diets without suitable sterols. Incorporating sterol supplements into pollen substitutes using this method will enable beekeepers to rear healthier, longer-lived colonies to meet the growing demands for global crop pollination. It could also reduce competition between bee species for access to natural floral resources, stemming the decline of wild bee populations.
O_LIPlants produce floral nectar as a reward for pollinators, which contains carbohydrates and amino acids (AAs). We designed experiments to test whether pollinators could exert selection pressure on the profiles of AAs in nectar. C_LIO_LIWe used HPLC to measure the free amino acids and sugars in the nectar of 102 UK plant species. Six distinct profiles of essential amino acids (EAAs) were defined using the relative proportions of AAs with a clustering algorithm; we then tested bumblebee (Bombus terrestris) preferences for the EAA profiles and proline using a two-choice assay. C_LIO_LIWe found a phylogenetic signal for the proportions of phenylalanine, methionine and proline as well as the total concentrations of essential and non-essential AAs. However, there was no phylogenetic signal for EAA profile. Bumblebees did not exhibit a preference for any of the six EAA nectar profiles, however, four of the EAA profiles stimulated feeding. In contrast, bumblebees avoided proline in an inverse concentration-dependent manner. C_LIO_LIOur data indicate that bees are likely to have mechanisms for the post-ingestive evaluation of free AAs in solution but are unlikely to taste EAAs at nectar-relevant quantities. We predict that EAAs increase nectar value to bumblebees post-ingestively. C_LI
Bees are important pollinators of agricultural crops, but their populations are at risk when pesticides are used. One of the largest risks bees face is poisoning of floral nectar and pollen by insecticides. Studies of bee detection of neonicotinoids have reported contradictory evidence about whether bees can taste these pesticides in sucrose solutions and hence avoid them. Here, we use an assay for the detection of food aversion combined with single-sensillum electrophysiology to test whether the mouthparts of the buff-tailed bumblebee (Bombus terrestris) detect the presence of pesticides in a solution that mimicked the nectar of oilseed rape (Brassica napus). Bees did not avoid consuming solutions containing concentrations of imidacloprid, thiamethoxam, clothianidin, or sulfoxaflor spanning six orders of magnitude, even when these solutions contained lethal doses. Only extremely high concentrations of the pesticides altered spiking in gustatory neurons through a slight reduction in firing rate or change in the rate of adaptation. These data provide strong evidence that bumblebees cannot detect or avoid field-relevant concentrations of pesticides using information from their mouthparts. As bees rarely contact floral nectar with other body parts, we predict that they are at high risk of unwittingly consuming pesticides in the nectar of pesticide-treated crops.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causal agent of COVID-19, can infect animals by binding to the angiotensin-converting enzyme 2 (ACE2). Equine infection appears possible due to high homology ({approx}97%) between human and equine ACE2, evidence of in vitro infection in cell lines expressing equine ACE2, and evidence of seroconversion in horses after exposure to persons infected with SARS-CoV-2. Our objective was to examine susceptibility of cultured primary equine bronchial epithelial cells (EBECs) to a SARS-CoV-2 pseudovirus relative to human bronchial epithelial cells (HBECs; positive control). ACE2 expression in EBECs detected by immunofluorescence, western immunoblotting, and flow cytometry was lower in EBECs than in HBECs. EBECs were transduced with a lentivirus pseudotyped with the SARS-CoV-2 spike protein that binds to ACE2 and expresses the enhanced green fluorescent protein (eGFP) as a reporter. Cells were co-cultivated with the pseudovirus at a multiplicity of infection of 0.1 for 6 hours, washed, and maintained in media. After 96 hours, eGFP expression in EBECs was demonstrated by fluorescence microscopy, and mean {Delta} Ct values from quantitative PCR were significantly (P < 0.0001) higher in HBECs (8.78) than HBECs (3.24) indicating lower infectivity in EBECs. Equine respiratory tract cells were susceptible to infection with a SARS-CoV-2 pseudovirus. Lower replication efficiency in EBECs suggests that horses are unlikely to be an important zoonotic host of SARS-CoV-2, but viral mutations could render some strains more infectious to horses. Serological and virological monitoring of horses in contact with persons shedding SARS-CoV-2 is warranted. IMPORTANCEThis study provides the first published evidence for SARS-CoV-2 pseudovirus infection in equine airway epithelial cells, which were less susceptible to infection than cells of human origin. This was presumably due to lower ACE2 expression in equine cells, lower viral affinity for equine ACE2, or both. Our results are important considering recent evidence for asymptomatic seroconversion in horses following exposure to COVID-19 positive humans, despite this lower susceptibility, and increased affinity of viral variants of concern for equine ACE2 compared to ancestral strains. Thus, there is great need to better characterize SARS-CoV-2 susceptibility in horses for the benefit of veterinary and human health.