Project description:During the nest-founding phase of the bumble bee colony cycle, queens undergo striking changes in maternal care behavior. Early in the founding phase, prior to the emergence of workers in the nest, queens are reproductive and also provision and feed their offspring. However, later in the founding phase, queens cease feeding offspring and become specialized on reproduction. This transition is synchronized with the emergence of workers in the colony, who assume the task of feeding their siblings. Using a social manipulation experiment, we tested the hypothesis that workers socially regulate the transition from feeding brood to specialization on reproduction in nest-founding bumble bee queens. Consistent with this hypothesis, we found that early-stage queens with workers prematurely added to their nests reduce their brood-feeding behavior and increase egg-laying, and likewise, late-stage queens increase their brood-feeding behavior and decrease egg-laying when workers are removed from their nests. Further, brood-feeding and egg-laying behavior were negatively correlated in these queens. We used an Agilent brain EST-based microarray to explore a second hypothesis, that workers alter brain gene expression in nest-founding queens. We found evidence that brain gene expression in nest-founding queens is altered by the presence of workers, with the effect much stronger in late-stage founding queens. Additionally, expression levels of some genes were correlated with quantitative differences in brood-feeding and egg-laying behavior. This study provides new insights into how the transition from feeding brood to specialization on reproduction in bumble bee queens is regulated during the nest initiation phase of the colony cycle.
Project description:Our aims in this study were: 1) to identify the miRNAs of the bumble bees Bombus terrestris and B. impatiens; 2) to compare the total numbers of miRNAs between both bumble bee species and between them and the honey bee, Apis mellifera; and 3) to test whether the sequences and expression patterns of miRNAs were conserved between species. To investigate each of these aims we used miRNA-seq (deep sequencing of miRNA-enriched libraries) in B. terrestris, and bioinformatics prediction programs to identify miRNAs in both Bombus species. We identified 131 miRNAs in B. terrestris, and 114 in B. impatiens; of these, 17 were new miRNAs that had not previously been sequenced in any species. We found a striking level of difference in the miRNAs present between Bombus and A. mellifera, with 103 miRNAs in A. mellifera not being present in the genomes of the two bumble bees.
Project description:Our aims in this study were: 1) to identify the miRNAs of the bumble bees Bombus terrestris and B. impatiens; 2) to compare the total numbers of miRNAs between both bumble bee species and between them and the honey bee, Apis mellifera; and 3) to test whether the sequences and expression patterns of miRNAs were conserved between species. To investigate each of these aims we used miRNA-seq (deep sequencing of miRNA-enriched libraries) in B. terrestris, and bioinformatics prediction programs to identify miRNAs in both Bombus species. We identified 131 miRNAs in B. terrestris, and 114 in B. impatiens; of these, 17 were new miRNAs that had not previously been sequenced in any species. We found a striking level of difference in the miRNAs present between Bombus and A. mellifera, with 103 miRNAs in A. mellifera not being present in the genomes of the two bumble bees. miRNA profiles of Bombus terrestris at two developmental stages in larvae. This submission represents 'Bombus terrestris' component of study.
Project description:Our two main aims were 1) to isolate age-related changes in gene expression in queens of the eusocial bumble bee, Bombus terrestris; and 2) to determine whether experimentally increasing the costs of reproduction (by removing eggs) caused changes in age-related gene expression in these queens. To address these aims we extracted RNA from three key tissues (brain, fat body and ovary) from queens at two time points (10% and 60% mortality phases). Each of these queens had experienced one of two treatments: an egg removal (R) treatment (to increase the costs of reproduction) and an egg removal and replacement (C) treatment (to control for the effects of disturbance caused by egg removal).
Project description:Pesticides pose a potential threat to bee health, especially in combination with other stressors, like parasites. However, pesticide risk assessment tests them in isolation from other stresses. We tested acute oral doses of three pesticides - glyphosate, Amistar and sulfoxaflor - on the bumblebee, Bombus terrestris, alongside the gut parasite Crithidia bombi. We found no impact of any pesticide on parasite intensity and no impact of sulfoxaflor or glyphosate on survival or weight change. Amistar caused weight loss and 19-41% mortality. Haemoproteome analysis showed various protein dysregulations. The major pathways dysregulated are those involved in insect defences and immune responses, with Amistar having the strongest impact on these. Our results show that while no response can be seen at a whole organism level, MALDI BeeTyping® can detect effects. Mass spectrometry analysis of bee haemolymph represent a pertinent tool to evaluate the stressor impacts on bee health, even at the individual scale.
Project description:In Apis mellifera, the female eggs can develop into workers or queen depending on the diet offered during early development. The outputs of the developed honeybee females are two morphs with particular morphological traits and related physiology. Among the specialized structures in workers the hind tibia forms the corbicula or the pollen basket, a smooth region surrounded by a row of a long scopal hairs, used for carrying pollen and other materials to the nest. This morphological trait and the respective behaviour are absent in queens. Herein we show details of the initial steps of hind legs morphogenesis in honeybee castes. Using results from the hybridization of whole genome-based oligonucleotide arrays with RNA samples from hind leg imaginal discs of pre-pupa honeybees of both castes we present a list of differentially expressed genes. Analysis used one dye-swap combination to compare workers and queens hind leg development at prepupal stages when juvenile hormone titers is much higher in queens
Project description:Social organization is commonly dynamic with extreme examples in annual eusocial insects ("annual superorganisms"), but the signals and mechanisms regulating social organization remained elusive. In annual bumble bee colonies, larvae with a close contact to a queen do not differentiate into gynes, pupate at an earlier age, and are commonly smaller than siblings that do not contact a queen. We combined detailed observations, proteomics, microRNA transcriptomics, and gland removal surgery, to study the regulation of brood development and division of labor in the model bumble bee Bombus terrestris. We found that regurgitates fed to larvae by queens and workers differ in their protein and microRNA composition. The proteome of the regurgitate overlaps significantly with that of the mandibular (MG) and hypopharyngeal glands (HPG), suggesting that these exocrine glands are the sources of some regurgitate proteins. The MG and HPG proteomes , but not that of the salivary glands, differed between queens and workers, with the caste-specificity preserved for the MG and regurgitate proteomes. Queens subjected to a surgical removal of the MG showed normal behavior and brood care, but failed to manipulate the developmental program of the brood they reared. These findings suggest that substances in the queen MG are fed to larvae and influence their developmental program. As the colony grows, an increasing number of workers feed larvae and by that reduce the effects of the queen substances, such that she can no longer manipulate the development of all larvae, and the colony switches from producing workers (ergonomic phase) to gynes (reproductive phase).