Association of Sucrose Responsiveness, Ovary Size, and <i>Vitellogenin</i> mRNA Level in Worker Honey Bees.

<p>(A) Means and standard errors of the ovary sizes in the subsets of bees selected from the extreme tails of the ovariole number and GRS and distributions; LL = small ovaries (3–9 ovarioles) and low GRS (0–2), HH = large ovaries (17–29 ovarioles) and high GRS (4–7), <i>n</i> = 44 and 43, respectively. L and H were laboratory handling controls that were selected only on the basis of ovary size, GRS was not determined (<i>n</i> = 10; ovariole number was 3–9 and 12–23, respectively, H spanned lower ovary sizes than HH as there were not a sufficient number of bees to obtain in the 17–29 range). HH and LL differ significantly for ovariole number (P<0.0001, one-way ANOVA). (B) Means and standard errors of the log-transformed <i>vitellogenin</i> mRNA expression level given as a relative quantity (RQ). Bees with large ovaries and high GRS are characterized by significantly higher <i>vitellogenin</i> levels on average (P<0.005, one-way ANOVA). The controls show no significant effect of handling.</p

Relationships between Sucrose Responsiveness and Ovary Size in Worker Honey Bees.

<p>(A) Pie charts showing the distributions of ovary sizes between bees with low (GRS 0–3, <i>n</i> = 141) and high (GRS 4–9, <i>n</i> = 149) responsiveness to sucrose. Ovary sizes are given as the total number of ovarioles per bee (i.e., summing over both ovaries). (B) Comparison between the means and standard errors of ovary sizes between bees with low and high sucrose responsiveness. Bees with high GRS scores are characterized by significantly larger ovaries on average.</p

Candidate genes involved in neurological signaling or regulation in QTL region on chromosome 1.

<p>Candidate genes involved in neurological signaling or regulation in QTL region on chromosome 1.</p

Candidate genes involved in neurological signaling or regulation in QTL region on chromosome 9.

<p>Candidate genes involved in neurological signaling or regulation in QTL region on chromosome 9.</p

Fine-Scale Linkage Mapping Reveals a Small Set of Candidate Genes Influencing Honey Bee Grooming Behavior in Response to Varroa Mites

<div><p>Populations of honey bees in North America have been experiencing high annual colony mortality for 15–20 years. Many apicultural researchers believe that introduced parasites called Varroa mites (<em>V. destructor</em>) are the most important factor in colony deaths. One important resistance mechanism that limits mite population growth in colonies is the ability of some lines of honey bees to groom mites from their bodies. To search for genes influencing this trait, we used an Illumina Bead Station genotyping array to determine the genotypes of several hundred worker bees at over a thousand single-nucleotide polymorphisms in a family that was apparently segregating for alleles influencing this behavior. Linkage analyses provided a genetic map with 1,313 markers anchored to genome sequence. Genotypes were analyzed for association with grooming behavior, measured as the time that individual bees took to initiate grooming after mites were placed on their thoraces. Quantitative-trait-locus interval mapping identified a single chromosomal region that was significant at the chromosome-wide level (p<0.05) on chromosome 5 with a LOD score of 2.72. The 95% confidence interval for quantitative trait locus location contained only 27 genes (honey bee official gene annotation set 2) including <em>Atlastin</em>, <em>Ataxin</em> and <em>Neurexin-1 (AmNrx1)</em>, which have potential neurodevelopmental and behavioral effects. <em>Atlastin</em> and <em>Ataxin</em> homologs are associated with neurological diseases in humans. <em>AmNrx1</em> codes for a presynaptic protein with many alternatively spliced isoforms. <em>Neurexin-1</em> influences the growth, maintenance and maturation of synapses in the brain, as well as the type of receptors most prominent within synapses. <em>Neurexin-1</em> has also been associated with autism spectrum disorder and schizophrenia in humans, and self-grooming behavior in mice.</p> </div

Candidate genes for honey bee mite-grooming behavior and their putative functions.

<p>Candidate genes for honey bee mite-grooming behavior and their putative functions.</p

Map of QTL location for groom-1 on chromosome 5.

<p>The physical location in base pairs of SNP probes in the honey bee genome assembly (Amel 4.0) is indicated to the right of the bar. The large number associated with the last SNP marker refers to its location in a contig that was not assigned to a chromosome prior to this study. Numbers to the left of the bar are distances in centimorgans. The red line indicates the LOD score for the likelihood that a QTL influencing grooming behavior is linked. The dotted line indicates the chromosome-wide empirical significance threshold of 0.05 as determined by 1000 permutations of phenotype data. Probe sequences matching the chromosome positions are available in <b><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0047269#pone.0047269.s001" target="_blank">Table S1</a></b>.</p