Concordance between the mitochondrial haplotypes of the Eastern honey bee, Apis cerana, and its ectoparasitic Varroa mites across the Isthmus of Kra in Thailand has suggested that local host-pathogen co-evolution may be responsible for the geographic distribution of particular genotypes. To investigate nuclear microsatellites population structure in A. cerana, single workers of A. cerana colonies from Thailand were genotyped at 18 microsatellite loci. The loci showed intermediate to high levels of heterozygosity and a range of allele numbers. The analyses confirmed a fundamental subdivision of the Thai A. cerana population into the "Asia Mainland" and "Sundaland" regions at the Isthmus of Kra. However, the nuclear microsatellite differentiation was less distinct than mtDNA haplotype differences, suggesting male-biased dispersal and population admixture. Overall, samples showed a weak isolation-by-distance effect. The isolated population on Samui island was most differentiated from the other samples. The results do not support our initial hypothesis of local host-pathogen co-evolution, which predicts a strict correspondence between the nuclear genome and the lineage of parasitic Varroa mite of the A. cerana samples, because the gene flow indicated by our nuclear microsatellite markers should also mix potential Varroa resistance alleles among subpopulations. Instead, our study suggests that the coincidental distribution of Varroa lineages and A. cerana population structure in Thailand are the result of biogeographic history and current migration patterns Keywords: biogeography | co-evolution | local adaptation | microsatellites | population structure | apis cerana | honey bees | Thailand | Varroa mite association | social insects | biology Article:

International audienceApis mellifera experiences large population declines in the USA and honeybee health is affected by many, potentially interacting factors that need to be addressed through a variety of approaches. In this context, we evaluated the impact of nutritional manipulations on worker physiology and colony demography. Specifically, we manipulated protein availability by feeding colonies on royal jelly, low-quality pollen, or regular pollen stores. After acclimation to these treatments, experimental cohorts of workers were introduced and later assessed with regards to life expectancy, protein content, and intestinal stem cell proliferation. We also monitored their hives for the amount of workers, brood, and pollen trapped in front of the hive entrances. Workers that fed on royal jelly showed a reduced rate of intestinal stem cell proliferation at nurse bee age. Total soluble protein content of individuals and adult worker lifespan were not systematically affected. However, we cannot exclude an auxiliary role of poor nutrition to declining bee health by weakening the intestinal epithelium. In contrast to the weak experimental effects on individual variables, the brood production differed drastically among the experimental hives. Although not yet replicated, this observation might indicate that hive demographic plasticity rather than individual plasticity is important for acclimation to different food regimes